2 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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13 * accompanied this code).
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25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/scopeDesc.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "interpreter/interpreter.hpp"
33 #include "interpreter/linkResolver.hpp"
34 #include "interpreter/oopMapCache.hpp"
35 #include "jvmtifiles/jvmtiEnv.hpp"
36 #include "memory/oopFactory.hpp"
37 #include "memory/universe.inline.hpp"
38 #include "oops/instanceKlass.hpp"
39 #include "oops/objArrayOop.hpp"
40 #include "oops/oop.inline.hpp"
41 #include "oops/symbol.hpp"
42 #include "prims/jvm_misc.hpp"
43 #include "prims/jvmtiExport.hpp"
44 #include "prims/jvmtiThreadState.hpp"
45 #include "prims/privilegedStack.hpp"
46 #include "runtime/aprofiler.hpp"
47 #include "runtime/arguments.hpp"
48 #include "runtime/biasedLocking.hpp"
49 #include "runtime/deoptimization.hpp"
50 #include "runtime/fprofiler.hpp"
51 #include "runtime/frame.inline.hpp"
52 #include "runtime/init.hpp"
53 #include "runtime/interfaceSupport.hpp"
54 #include "runtime/java.hpp"
55 #include "runtime/javaCalls.hpp"
56 #include "runtime/jniPeriodicChecker.hpp"
57 #include "runtime/memprofiler.hpp"
58 #include "runtime/mutexLocker.hpp"
59 #include "runtime/objectMonitor.hpp"
60 #include "runtime/osThread.hpp"
61 #include "runtime/safepoint.hpp"
62 #include "runtime/sharedRuntime.hpp"
63 #include "runtime/statSampler.hpp"
64 #include "runtime/stubRoutines.hpp"
65 #include "runtime/task.hpp"
66 #include "runtime/threadCritical.hpp"
67 #include "runtime/threadLocalStorage.hpp"
68 #include "runtime/vframe.hpp"
69 #include "runtime/vframeArray.hpp"
70 #include "runtime/vframe_hp.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "runtime/vm_operations.hpp"
73 #include "services/attachListener.hpp"
74 #include "services/management.hpp"
75 #include "services/threadService.hpp"
76 #include "utilities/defaultStream.hpp"
77 #include "utilities/dtrace.hpp"
78 #include "utilities/events.hpp"
79 #include "utilities/preserveException.hpp"
80 #ifdef TARGET_OS_FAMILY_linux
81 # include "os_linux.inline.hpp"
82 # include "thread_linux.inline.hpp"
84 #ifdef TARGET_OS_FAMILY_solaris
85 # include "os_solaris.inline.hpp"
86 # include "thread_solaris.inline.hpp"
88 #ifdef TARGET_OS_FAMILY_windows
89 # include "os_windows.inline.hpp"
90 # include "thread_windows.inline.hpp"
93 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
94 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
95 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
98 #include "c1/c1_Compiler.hpp"
101 #include "opto/c2compiler.hpp"
102 #include "opto/idealGraphPrinter.hpp"
105 #ifdef DTRACE_ENABLED
107 // Only bother with this argument setup if dtrace is available
109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
110 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
111 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
112 intptr_t, intptr_t, bool);
113 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
114 intptr_t, intptr_t, bool);
116 #define DTRACE_THREAD_PROBE(probe, javathread) \
118 ResourceMark rm(this); \
120 const char* name = (javathread)->get_thread_name(); \
121 len = strlen(name); \
122 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
124 java_lang_Thread::thread_id((javathread)->threadObj()), \
125 (javathread)->osthread()->thread_id(), \
126 java_lang_Thread::is_daemon((javathread)->threadObj())); \
129 #else // ndef DTRACE_ENABLED
131 #define DTRACE_THREAD_PROBE(probe, javathread)
133 #endif // ndef DTRACE_ENABLED
139 // - ConcurrentMarkSweepThread
143 // ======= Thread ========
145 // Support for forcing alignment of thread objects for biased locking
146 void* Thread::operator new(size_t size) {
147 if (UseBiasedLocking) {
148 const int alignment = markOopDesc::biased_lock_alignment;
149 size_t aligned_size = size + (alignment - sizeof(intptr_t));
150 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
151 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
152 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
153 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
154 "JavaThread alignment code overflowed allocated storage");
155 if (TraceBiasedLocking) {
156 if (aligned_addr != real_malloc_addr)
157 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
158 real_malloc_addr, aligned_addr);
160 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
163 return CHeapObj::operator new(size);
167 void Thread::operator delete(void* p) {
168 if (UseBiasedLocking) {
169 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
170 CHeapObj::operator delete(real_malloc_addr);
172 CHeapObj::operator delete(p);
177 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
182 // stack and get_thread
183 set_stack_base(NULL);
188 // allocated data structures
190 set_resource_area(new ResourceArea());
191 set_handle_area(new HandleArea(NULL));
192 set_active_handles(NULL);
193 set_free_handle_block(NULL);
194 set_last_handle_mark(NULL);
196 // This initial value ==> never claimed.
199 // the handle mark links itself to last_handle_mark
200 new HandleMark(this);
202 // plain initialization
203 debug_only(_owned_locks = NULL;)
204 debug_only(_allow_allocation_count = 0;)
205 NOT_PRODUCT(_allow_safepoint_count = 0;)
206 NOT_PRODUCT(_skip_gcalot = false;)
207 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)
208 _jvmti_env_iteration_count = 0;
209 set_allocated_bytes(0);
210 _vm_operation_started_count = 0;
211 _vm_operation_completed_count = 0;
212 _current_pending_monitor = NULL;
213 _current_pending_monitor_is_from_java = true;
214 _current_waiting_monitor = NULL;
215 _num_nested_signal = 0;
218 omFreeProvision = 32 ;
222 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
225 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
226 _hashStateX = os::random() ;
227 _hashStateY = 842502087 ;
228 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
229 _hashStateW = 273326509 ;
236 // Many of the following fields are effectively final - immutable
237 // Note that nascent threads can't use the Native Monitor-Mutex
238 // construct until the _MutexEvent is initialized ...
239 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
240 // we might instead use a stack of ParkEvents that we could provision on-demand.
241 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
243 _ParkEvent = ParkEvent::Allocate (this) ;
244 _SleepEvent = ParkEvent::Allocate (this) ;
245 _MutexEvent = ParkEvent::Allocate (this) ;
246 _MuxEvent = ParkEvent::Allocate (this) ;
248 #ifdef CHECK_UNHANDLED_OOPS
249 if (CheckUnhandledOops) {
250 _unhandled_oops = new UnhandledOops(this);
252 #endif // CHECK_UNHANDLED_OOPS
254 if (UseBiasedLocking) {
255 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
256 assert(this == _real_malloc_address ||
257 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
258 "bug in forced alignment of thread objects");
263 void Thread::initialize_thread_local_storage() {
264 // Note: Make sure this method only calls
265 // non-blocking operations. Otherwise, it might not work
266 // with the thread-startup/safepoint interaction.
268 // During Java thread startup, safepoint code should allow this
269 // method to complete because it may need to allocate memory to
270 // store information for the new thread.
272 // initialize structure dependent on thread local storage
273 ThreadLocalStorage::set_thread(this);
275 // set up any platform-specific state.
276 os::initialize_thread();
280 void Thread::record_stack_base_and_size() {
281 set_stack_base(os::current_stack_base());
282 set_stack_size(os::current_stack_size());
287 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
288 ObjectSynchronizer::omFlush (this) ;
290 // deallocate data structures
291 delete resource_area();
292 // since the handle marks are using the handle area, we have to deallocated the root
293 // handle mark before deallocating the thread's handle area,
294 assert(last_handle_mark() != NULL, "check we have an element");
295 delete last_handle_mark();
296 assert(last_handle_mark() == NULL, "check we have reached the end");
298 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
299 // We NULL out the fields for good hygiene.
300 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
301 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
302 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
303 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
305 delete handle_area();
307 // osthread() can be NULL, if creation of thread failed.
308 if (osthread() != NULL) os::free_thread(osthread());
312 // clear thread local storage if the Thread is deleting itself
313 if (this == Thread::current()) {
314 ThreadLocalStorage::set_thread(NULL);
316 // In the case where we're not the current thread, invalidate all the
317 // caches in case some code tries to get the current thread or the
318 // thread that was destroyed, and gets stale information.
319 ThreadLocalStorage::invalidate_all();
321 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
324 // NOTE: dummy function for assertion purpose.
326 ShouldNotReachHere();
330 // Private method to check for dangling thread pointer
331 void check_for_dangling_thread_pointer(Thread *thread) {
332 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
333 "possibility of dangling Thread pointer");
339 // Tracing method for basic thread operations
340 void Thread::trace(const char* msg, const Thread* const thread) {
341 if (!TraceThreadEvents) return;
344 const char *name = "non-Java thread";
346 if (thread->is_Java_thread()
347 && !thread->is_Compiler_thread()) {
348 // The Threads_lock must be held to get information about
349 // this thread but may not be in some situations when
350 // tracing thread events.
351 bool release_Threads_lock = false;
352 if (!Threads_lock->owned_by_self()) {
353 Threads_lock->lock();
354 release_Threads_lock = true;
356 JavaThread* jt = (JavaThread *)thread;
357 name = (char *)jt->get_thread_name();
358 oop thread_oop = jt->threadObj();
359 if (thread_oop != NULL) {
360 prio = java_lang_Thread::priority(thread_oop);
362 if (release_Threads_lock) {
363 Threads_lock->unlock();
366 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
371 ThreadPriority Thread::get_priority(const Thread* const thread) {
372 trace("get priority", thread);
373 ThreadPriority priority;
374 // Can return an error!
375 (void)os::get_priority(thread, priority);
376 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
380 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
381 trace("set priority", thread);
382 debug_only(check_for_dangling_thread_pointer(thread);)
383 // Can return an error!
384 (void)os::set_priority(thread, priority);
388 void Thread::start(Thread* thread) {
389 trace("start", thread);
390 // Start is different from resume in that its safety is guaranteed by context or
391 // being called from a Java method synchronized on the Thread object.
392 if (!DisableStartThread) {
393 if (thread->is_Java_thread()) {
394 // Initialize the thread state to RUNNABLE before starting this thread.
395 // Can not set it after the thread started because we do not know the
396 // exact thread state at that time. It could be in MONITOR_WAIT or
397 // in SLEEPING or some other state.
398 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
399 java_lang_Thread::RUNNABLE);
401 os::start_thread(thread);
405 // Enqueue a VM_Operation to do the job for us - sometime later
406 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
407 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
408 VMThread::execute(vm_stop);
413 // Check if an external suspend request has completed (or has been
414 // cancelled). Returns true if the thread is externally suspended and
417 // The bits parameter returns information about the code path through
418 // the routine. Useful for debugging:
420 // set in is_ext_suspend_completed():
421 // 0x00000001 - routine was entered
422 // 0x00000010 - routine return false at end
423 // 0x00000100 - thread exited (return false)
424 // 0x00000200 - suspend request cancelled (return false)
425 // 0x00000400 - thread suspended (return true)
426 // 0x00001000 - thread is in a suspend equivalent state (return true)
427 // 0x00002000 - thread is native and walkable (return true)
428 // 0x00004000 - thread is native_trans and walkable (needed retry)
430 // set in wait_for_ext_suspend_completion():
431 // 0x00010000 - routine was entered
432 // 0x00020000 - suspend request cancelled before loop (return false)
433 // 0x00040000 - thread suspended before loop (return true)
434 // 0x00080000 - suspend request cancelled in loop (return false)
435 // 0x00100000 - thread suspended in loop (return true)
436 // 0x00200000 - suspend not completed during retry loop (return false)
439 // Helper class for tracing suspend wait debug bits.
441 // 0x00000100 indicates that the target thread exited before it could
442 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
443 // 0x00080000 each indicate a cancelled suspend request so they don't
444 // count as wait failures either.
445 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
447 class TraceSuspendDebugBits : public StackObj {
451 bool called_by_wait; // meaningful when !is_wait
455 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
459 called_by_wait = _called_by_wait;
463 ~TraceSuspendDebugBits() {
466 // By default, don't trace bits for is_ext_suspend_completed() calls.
467 // That trace is very chatty.
470 if (!called_by_wait) {
471 // If tracing for is_ext_suspend_completed() is enabled, then only
472 // trace calls to it from wait_for_ext_suspend_completion()
478 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
479 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
480 MutexLocker ml(Threads_lock); // needed for get_thread_name()
484 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
485 jt->get_thread_name(), *bits);
487 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
492 #undef DEBUG_FALSE_BITS
495 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
496 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
498 bool did_trans_retry = false; // only do thread_in_native_trans retry once
499 bool do_trans_retry; // flag to force the retry
504 do_trans_retry = false;
507 // Thread is in the process of exiting. This is always checked
508 // first to reduce the risk of dereferencing a freed JavaThread.
513 if (!is_external_suspend()) {
514 // Suspend request is cancelled. This is always checked before
515 // is_ext_suspended() to reduce the risk of a rogue resume
516 // confusing the thread that made the suspend request.
521 if (is_ext_suspended()) {
522 // thread is suspended
527 // Now that we no longer do hard suspends of threads running
528 // native code, the target thread can be changing thread state
529 // while we are in this routine:
531 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
533 // We save a copy of the thread state as observed at this moment
534 // and make our decision about suspend completeness based on the
535 // copy. This closes the race where the thread state is seen as
536 // _thread_in_native_trans in the if-thread_blocked check, but is
537 // seen as _thread_blocked in if-thread_in_native_trans check.
538 JavaThreadState save_state = thread_state();
540 if (save_state == _thread_blocked && is_suspend_equivalent()) {
541 // If the thread's state is _thread_blocked and this blocking
542 // condition is known to be equivalent to a suspend, then we can
543 // consider the thread to be externally suspended. This means that
544 // the code that sets _thread_blocked has been modified to do
545 // self-suspension if the blocking condition releases. We also
546 // used to check for CONDVAR_WAIT here, but that is now covered by
547 // the _thread_blocked with self-suspension check.
549 // Return true since we wouldn't be here unless there was still an
550 // external suspend request.
553 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
554 // Threads running native code will self-suspend on native==>VM/Java
555 // transitions. If its stack is walkable (should always be the case
556 // unless this function is called before the actual java_suspend()
557 // call), then the wait is done.
560 } else if (!called_by_wait && !did_trans_retry &&
561 save_state == _thread_in_native_trans &&
562 frame_anchor()->walkable()) {
563 // The thread is transitioning from thread_in_native to another
564 // thread state. check_safepoint_and_suspend_for_native_trans()
565 // will force the thread to self-suspend. If it hasn't gotten
566 // there yet we may have caught the thread in-between the native
567 // code check above and the self-suspend. Lucky us. If we were
568 // called by wait_for_ext_suspend_completion(), then it
569 // will be doing the retries so we don't have to.
571 // Since we use the saved thread state in the if-statement above,
572 // there is a chance that the thread has already transitioned to
573 // _thread_blocked by the time we get here. In that case, we will
574 // make a single unnecessary pass through the logic below. This
575 // doesn't hurt anything since we still do the trans retry.
579 // Once the thread leaves thread_in_native_trans for another
580 // thread state, we break out of this retry loop. We shouldn't
581 // need this flag to prevent us from getting back here, but
582 // sometimes paranoia is good.
583 did_trans_retry = true;
585 // We wait for the thread to transition to a more usable state.
586 for (int i = 1; i <= SuspendRetryCount; i++) {
587 // We used to do an "os::yield_all(i)" call here with the intention
588 // that yielding would increase on each retry. However, the parameter
589 // is ignored on Linux which means the yield didn't scale up. Waiting
590 // on the SR_lock below provides a much more predictable scale up for
591 // the delay. It also provides a simple/direct point to check for any
592 // safepoint requests from the VMThread
594 // temporarily drops SR_lock while doing wait with safepoint check
595 // (if we're a JavaThread - the WatcherThread can also call this)
596 // and increase delay with each retry
597 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
599 // check the actual thread state instead of what we saved above
600 if (thread_state() != _thread_in_native_trans) {
601 // the thread has transitioned to another thread state so
602 // try all the checks (except this one) one more time.
603 do_trans_retry = true;
610 } while (do_trans_retry);
617 // Wait for an external suspend request to complete (or be cancelled).
618 // Returns true if the thread is externally suspended and false otherwise.
620 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
622 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
623 false /* !called_by_wait */, bits);
625 // local flag copies to minimize SR_lock hold time
630 // set a marker so is_ext_suspend_completed() knows we are the caller
633 // We use reset_bits to reinitialize the bits value at the top of
634 // each retry loop. This allows the caller to make use of any
635 // unused bits for their own marking purposes.
639 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
640 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
642 pending = is_external_suspend();
644 // must release SR_lock to allow suspension to complete
647 // A cancelled suspend request is the only false return from
648 // is_ext_suspend_completed() that keeps us from entering the
659 for (int i = 1; i <= retries; i++) {
660 *bits = reset_bits; // reinit to only track last retry
662 // We used to do an "os::yield_all(i)" call here with the intention
663 // that yielding would increase on each retry. However, the parameter
664 // is ignored on Linux which means the yield didn't scale up. Waiting
665 // on the SR_lock below provides a much more predictable scale up for
666 // the delay. It also provides a simple/direct point to check for any
667 // safepoint requests from the VMThread
670 MutexLocker ml(SR_lock());
671 // wait with safepoint check (if we're a JavaThread - the WatcherThread
672 // can also call this) and increase delay with each retry
673 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
675 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
678 // It is possible for the external suspend request to be cancelled
679 // (by a resume) before the actual suspend operation is completed.
680 // Refresh our local copy to see if we still need to wait.
681 pending = is_external_suspend();
685 // A cancelled suspend request is the only false return from
686 // is_ext_suspend_completed() that keeps us from staying in the
698 // thread did not suspend after all our retries
704 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
706 // This should not need to be atomic as the only way for simultaneous
707 // updates is via interrupts. Even then this should be rare or non-existant
708 // and we don't care that much anyway.
710 int index = _jmp_ring_index;
711 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
712 _jmp_ring[index]._target = (intptr_t) target;
713 _jmp_ring[index]._instruction = (intptr_t) instr;
714 _jmp_ring[index]._file = file;
715 _jmp_ring[index]._line = line;
719 // Called by flat profiler
720 // Callers have already called wait_for_ext_suspend_completion
721 // The assertion for that is currently too complex to put here:
722 bool JavaThread::profile_last_Java_frame(frame* _fr) {
723 bool gotframe = false;
724 // self suspension saves needed state.
725 if (has_last_Java_frame() && _anchor.walkable()) {
726 *_fr = pd_last_frame();
732 void Thread::interrupt(Thread* thread) {
733 trace("interrupt", thread);
734 debug_only(check_for_dangling_thread_pointer(thread);)
735 os::interrupt(thread);
738 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
739 trace("is_interrupted", thread);
740 debug_only(check_for_dangling_thread_pointer(thread);)
741 // Note: If clear_interrupted==false, this simply fetches and
742 // returns the value of the field osthread()->interrupted().
743 return os::is_interrupted(thread, clear_interrupted);
748 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
749 jint thread_parity = _oops_do_parity;
750 if (thread_parity != strong_roots_parity) {
751 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
752 if (res == thread_parity) return true;
754 guarantee(res == strong_roots_parity, "Or else what?");
755 assert(SharedHeap::heap()->n_par_threads() > 0,
756 "Should only fail when parallel.");
760 assert(SharedHeap::heap()->n_par_threads() > 0,
761 "Should only fail when parallel.");
765 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
766 active_handles()->oops_do(f);
767 // Do oop for ThreadShadow
768 f->do_oop((oop*)&_pending_exception);
769 handle_area()->oops_do(f);
772 void Thread::nmethods_do(CodeBlobClosure* cf) {
773 // no nmethods in a generic thread...
776 void Thread::print_on(outputStream* st) const {
777 // get_priority assumes osthread initialized
778 if (osthread() != NULL) {
779 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
780 osthread()->print_on(st);
782 debug_only(if (WizardMode) print_owned_locks_on(st);)
785 // Thread::print_on_error() is called by fatal error handler. Don't use
786 // any lock or allocate memory.
787 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
788 if (is_VM_thread()) st->print("VMThread");
789 else if (is_Compiler_thread()) st->print("CompilerThread");
790 else if (is_Java_thread()) st->print("JavaThread");
791 else if (is_GC_task_thread()) st->print("GCTaskThread");
792 else if (is_Watcher_thread()) st->print("WatcherThread");
793 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
794 else st->print("Thread");
796 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
797 _stack_base - _stack_size, _stack_base);
800 st->print(" [id=%d]", osthread()->thread_id());
805 void Thread::print_owned_locks_on(outputStream* st) const {
806 Monitor *cur = _owned_locks;
808 st->print(" (no locks) ");
810 st->print_cr(" Locks owned:");
818 static int ref_use_count = 0;
820 bool Thread::owns_locks_but_compiled_lock() const {
821 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
822 if (cur != Compile_lock) return true;
832 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
833 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
834 // no threads which allow_vm_block's are held
835 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
836 // Check if current thread is allowed to block at a safepoint
837 if (!(_allow_safepoint_count == 0))
838 fatal("Possible safepoint reached by thread that does not allow it");
839 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
840 fatal("LEAF method calling lock?");
844 if (potential_vm_operation && is_Java_thread()
845 && !Universe::is_bootstrapping()) {
846 // Make sure we do not hold any locks that the VM thread also uses.
847 // This could potentially lead to deadlocks
848 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
849 // Threads_lock is special, since the safepoint synchronization will not start before this is
850 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
851 // since it is used to transfer control between JavaThreads and the VMThread
852 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
853 if ( (cur->allow_vm_block() &&
854 cur != Threads_lock &&
855 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
856 cur != VMOperationRequest_lock &&
857 cur != VMOperationQueue_lock) ||
858 cur->rank() == Mutex::special) {
859 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
864 if (GCALotAtAllSafepoints) {
865 // We could enter a safepoint here and thus have a gc
866 InterfaceSupport::check_gc_alot();
872 bool Thread::is_in_stack(address adr) const {
873 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
874 address end = os::current_stack_pointer();
875 if (stack_base() >= adr && adr >= end) return true;
881 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
882 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
883 // used for compilation in the future. If that change is made, the need for these methods
884 // should be revisited, and they should be removed if possible.
886 bool Thread::is_lock_owned(address adr) const {
887 return on_local_stack(adr);
890 bool Thread::set_as_starting_thread() {
891 // NOTE: this must be called inside the main thread.
892 return os::create_main_thread((JavaThread*)this);
895 static void initialize_class(Symbol* class_name, TRAPS) {
896 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
897 instanceKlass::cast(klass)->initialize(CHECK);
901 // Creates the initial ThreadGroup
902 static Handle create_initial_thread_group(TRAPS) {
903 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
904 instanceKlassHandle klass (THREAD, k);
906 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
908 JavaValue result(T_VOID);
909 JavaCalls::call_special(&result,
912 vmSymbols::object_initializer_name(),
913 vmSymbols::void_method_signature(),
916 Universe::set_system_thread_group(system_instance());
918 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
920 JavaValue result(T_VOID);
921 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
922 JavaCalls::call_special(&result,
925 vmSymbols::object_initializer_name(),
926 vmSymbols::threadgroup_string_void_signature(),
931 return main_instance;
934 // Creates the initial Thread
935 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
936 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
937 instanceKlassHandle klass (THREAD, k);
938 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
940 java_lang_Thread::set_thread(thread_oop(), thread);
941 java_lang_Thread::set_priority(thread_oop(), NormPriority);
942 thread->set_threadObj(thread_oop());
944 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
946 JavaValue result(T_VOID);
947 JavaCalls::call_special(&result, thread_oop,
949 vmSymbols::object_initializer_name(),
950 vmSymbols::threadgroup_string_void_signature(),
957 static void call_initializeSystemClass(TRAPS) {
958 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
959 instanceKlassHandle klass (THREAD, k);
961 JavaValue result(T_VOID);
962 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
963 vmSymbols::void_method_signature(), CHECK);
966 // General purpose hook into Java code, run once when the VM is initialized.
967 // The Java library method itself may be changed independently from the VM.
968 static void call_postVMInitHook(TRAPS) {
969 klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass();
970 instanceKlassHandle klass (THREAD, k);
971 if (klass.not_null()) {
972 JavaValue result(T_VOID);
973 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
974 vmSymbols::void_method_signature(),
979 static void reset_vm_info_property(TRAPS) {
980 // the vm info string
981 ResourceMark rm(THREAD);
982 const char *vm_info = VM_Version::vm_info_string();
984 // java.lang.System class
985 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
986 instanceKlassHandle klass (THREAD, k);
988 // setProperty arguments
989 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
990 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
993 JavaValue r(T_OBJECT);
995 // public static String setProperty(String key, String value);
996 JavaCalls::call_static(&r,
998 vmSymbols::setProperty_name(),
999 vmSymbols::string_string_string_signature(),
1006 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1007 assert(thread_group.not_null(), "thread group should be specified");
1008 assert(threadObj() == NULL, "should only create Java thread object once");
1010 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1011 instanceKlassHandle klass (THREAD, k);
1012 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1014 java_lang_Thread::set_thread(thread_oop(), this);
1015 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1016 set_threadObj(thread_oop());
1018 JavaValue result(T_VOID);
1019 if (thread_name != NULL) {
1020 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1021 // Thread gets assigned specified name and null target
1022 JavaCalls::call_special(&result,
1025 vmSymbols::object_initializer_name(),
1026 vmSymbols::threadgroup_string_void_signature(),
1027 thread_group, // Argument 1
1031 // Thread gets assigned name "Thread-nnn" and null target
1032 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1033 JavaCalls::call_special(&result,
1036 vmSymbols::object_initializer_name(),
1037 vmSymbols::threadgroup_runnable_void_signature(),
1038 thread_group, // Argument 1
1039 Handle(), // Argument 2
1045 java_lang_Thread::set_daemon(thread_oop());
1048 if (HAS_PENDING_EXCEPTION) {
1052 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1053 Handle threadObj(this, this->threadObj());
1055 JavaCalls::call_special(&result,
1058 vmSymbols::add_method_name(),
1059 vmSymbols::thread_void_signature(),
1066 // NamedThread -- non-JavaThread subclasses with multiple
1067 // uniquely named instances should derive from this.
1068 NamedThread::NamedThread() : Thread() {
1070 _processed_thread = NULL;
1073 NamedThread::~NamedThread() {
1074 if (_name != NULL) {
1075 FREE_C_HEAP_ARRAY(char, _name);
1080 void NamedThread::set_name(const char* format, ...) {
1081 guarantee(_name == NULL, "Only get to set name once.");
1082 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1083 guarantee(_name != NULL, "alloc failure");
1085 va_start(ap, format);
1086 jio_vsnprintf(_name, max_name_len, format, ap);
1090 // ======= WatcherThread ========
1092 // The watcher thread exists to simulate timer interrupts. It should
1093 // be replaced by an abstraction over whatever native support for
1094 // timer interrupts exists on the platform.
1096 WatcherThread* WatcherThread::_watcher_thread = NULL;
1097 volatile bool WatcherThread::_should_terminate = false;
1099 WatcherThread::WatcherThread() : Thread() {
1100 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1101 if (os::create_thread(this, os::watcher_thread)) {
1102 _watcher_thread = this;
1104 // Set the watcher thread to the highest OS priority which should not be
1105 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1106 // is created. The only normal thread using this priority is the reference
1107 // handler thread, which runs for very short intervals only.
1108 // If the VMThread's priority is not lower than the WatcherThread profiling
1109 // will be inaccurate.
1110 os::set_priority(this, MaxPriority);
1111 if (!DisableStartThread) {
1112 os::start_thread(this);
1117 void WatcherThread::run() {
1118 assert(this == watcher_thread(), "just checking");
1120 this->record_stack_base_and_size();
1121 this->initialize_thread_local_storage();
1122 this->set_active_handles(JNIHandleBlock::allocate_block());
1123 while(!_should_terminate) {
1124 assert(watcher_thread() == Thread::current(), "thread consistency check");
1125 assert(watcher_thread() == this, "thread consistency check");
1127 // Calculate how long it'll be until the next PeriodicTask work
1128 // should be done, and sleep that amount of time.
1129 size_t time_to_wait = PeriodicTask::time_to_wait();
1131 // we expect this to timeout - we only ever get unparked when
1132 // we should terminate
1134 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1136 jlong prev_time = os::javaTimeNanos();
1138 int res= _SleepEvent->park(time_to_wait);
1139 if (res == OS_TIMEOUT || _should_terminate)
1141 // spurious wakeup of some kind
1142 jlong now = os::javaTimeNanos();
1143 time_to_wait -= (now - prev_time) / 1000000;
1144 if (time_to_wait <= 0)
1150 if (is_error_reported()) {
1151 // A fatal error has happened, the error handler(VMError::report_and_die)
1152 // should abort JVM after creating an error log file. However in some
1153 // rare cases, the error handler itself might deadlock. Here we try to
1154 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1156 // This code is in WatcherThread because WatcherThread wakes up
1157 // periodically so the fatal error handler doesn't need to do anything;
1158 // also because the WatcherThread is less likely to crash than other
1162 if (!ShowMessageBoxOnError
1163 && (OnError == NULL || OnError[0] == '\0')
1164 && Arguments::abort_hook() == NULL) {
1165 os::sleep(this, 2 * 60 * 1000, false);
1166 fdStream err(defaultStream::output_fd());
1167 err.print_raw_cr("# [ timer expired, abort... ]");
1168 // skip atexit/vm_exit/vm_abort hooks
1172 // Wake up 5 seconds later, the fatal handler may reset OnError or
1173 // ShowMessageBoxOnError when it is ready to abort.
1174 os::sleep(this, 5 * 1000, false);
1178 PeriodicTask::real_time_tick(time_to_wait);
1180 // If we have no more tasks left due to dynamic disenrollment,
1181 // shut down the thread since we don't currently support dynamic enrollment
1182 if (PeriodicTask::num_tasks() == 0) {
1183 _should_terminate = true;
1187 // Signal that it is terminated
1189 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1190 _watcher_thread = NULL;
1191 Terminator_lock->notify();
1194 // Thread destructor usually does this..
1195 ThreadLocalStorage::set_thread(NULL);
1198 void WatcherThread::start() {
1199 if (watcher_thread() == NULL) {
1200 _should_terminate = false;
1201 // Create the single instance of WatcherThread
1202 new WatcherThread();
1206 void WatcherThread::stop() {
1207 // it is ok to take late safepoints here, if needed
1208 MutexLocker mu(Terminator_lock);
1209 _should_terminate = true;
1210 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1212 Thread* watcher = watcher_thread();
1213 if (watcher != NULL)
1214 watcher->_SleepEvent->unpark();
1216 while(watcher_thread() != NULL) {
1217 // This wait should make safepoint checks, wait without a timeout,
1218 // and wait as a suspend-equivalent condition.
1220 // Note: If the FlatProfiler is running, then this thread is waiting
1221 // for the WatcherThread to terminate and the WatcherThread, via the
1222 // FlatProfiler task, is waiting for the external suspend request on
1223 // this thread to complete. wait_for_ext_suspend_completion() will
1224 // eventually timeout, but that takes time. Making this wait a
1225 // suspend-equivalent condition solves that timeout problem.
1227 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1228 Mutex::_as_suspend_equivalent_flag);
1232 void WatcherThread::print_on(outputStream* st) const {
1233 st->print("\"%s\" ", name());
1234 Thread::print_on(st);
1238 // ======= JavaThread ========
1240 // A JavaThread is a normal Java thread
1242 void JavaThread::initialize() {
1243 // Initialize fields
1245 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1246 set_claimed_par_id(-1);
1248 set_saved_exception_pc(NULL);
1249 set_threadObj(NULL);
1251 set_entry_point(NULL);
1252 set_jni_functions(jni_functions());
1253 set_callee_target(NULL);
1254 set_vm_result(NULL);
1255 set_vm_result_2(NULL);
1256 set_vframe_array_head(NULL);
1257 set_vframe_array_last(NULL);
1258 set_deferred_locals(NULL);
1259 set_deopt_mark(NULL);
1260 set_deopt_nmethod(NULL);
1261 clear_must_deopt_id();
1262 set_monitor_chunks(NULL);
1264 set_thread_state(_thread_new);
1265 _terminated = _not_terminated;
1266 _privileged_stack_top = NULL;
1267 _array_for_gc = NULL;
1268 _suspend_equivalent = false;
1269 _in_deopt_handler = 0;
1270 _doing_unsafe_access = false;
1271 _stack_guard_state = stack_guard_unused;
1272 _exception_oop = NULL;
1274 _exception_handler_pc = 0;
1275 _exception_stack_size = 0;
1276 _is_method_handle_return = 0;
1277 _jvmti_thread_state= NULL;
1278 _should_post_on_exceptions_flag = JNI_FALSE;
1279 _jvmti_get_loaded_classes_closure = NULL;
1280 _interp_only_mode = 0;
1281 _special_runtime_exit_condition = _no_async_condition;
1282 _pending_async_exception = NULL;
1283 _is_compiling = false;
1284 _thread_stat = NULL;
1285 _thread_stat = new ThreadStatistics();
1286 _blocked_on_compilation = false;
1287 _jni_active_critical = 0;
1288 _do_not_unlock_if_synchronized = false;
1289 _cached_monitor_info = NULL;
1290 _parker = Parker::Allocate(this) ;
1293 _jmp_ring_index = 0;
1294 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1295 record_jump(NULL, NULL, NULL, 0);
1297 #endif /* PRODUCT */
1299 set_thread_profiler(NULL);
1300 if (FlatProfiler::is_active()) {
1301 // This is where we would decide to either give each thread it's own profiler
1302 // or use one global one from FlatProfiler,
1303 // or up to some count of the number of profiled threads, etc.
1304 ThreadProfiler* pp = new ThreadProfiler();
1306 set_thread_profiler(pp);
1309 // Setup safepoint state info for this thread
1310 ThreadSafepointState::create(this);
1312 debug_only(_java_call_counter = 0);
1314 // JVMTI PopFrame support
1315 _popframe_condition = popframe_inactive;
1316 _popframe_preserved_args = NULL;
1317 _popframe_preserved_args_size = 0;
1323 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1324 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1327 JavaThread::JavaThread(bool is_attaching) :
1330 , _satb_mark_queue(&_satb_mark_queue_set),
1331 _dirty_card_queue(&_dirty_card_queue_set)
1335 _is_attaching = is_attaching;
1336 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1339 bool JavaThread::reguard_stack(address cur_sp) {
1340 if (_stack_guard_state != stack_guard_yellow_disabled) {
1341 return true; // Stack already guarded or guard pages not needed.
1344 if (register_stack_overflow()) {
1345 // For those architectures which have separate register and
1346 // memory stacks, we must check the register stack to see if
1347 // it has overflowed.
1351 // Java code never executes within the yellow zone: the latter is only
1352 // there to provoke an exception during stack banging. If java code
1353 // is executing there, either StackShadowPages should be larger, or
1354 // some exception code in c1, c2 or the interpreter isn't unwinding
1356 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1358 enable_stack_yellow_zone();
1362 bool JavaThread::reguard_stack(void) {
1363 return reguard_stack(os::current_stack_pointer());
1367 void JavaThread::block_if_vm_exited() {
1368 if (_terminated == _vm_exited) {
1369 // _vm_exited is set at safepoint, and Threads_lock is never released
1370 // we will block here forever
1371 Threads_lock->lock_without_safepoint_check();
1372 ShouldNotReachHere();
1377 // Remove this ifdef when C1 is ported to the compiler interface.
1378 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1380 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1383 , _satb_mark_queue(&_satb_mark_queue_set),
1384 _dirty_card_queue(&_dirty_card_queue_set)
1387 if (TraceThreadEvents) {
1388 tty->print_cr("creating thread %p", this);
1391 _is_attaching = false;
1392 set_entry_point(entry_point);
1393 // Create the native thread itself.
1395 os::ThreadType thr_type = os::java_thread;
1396 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1398 os::create_thread(this, thr_type, stack_sz);
1400 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1401 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1402 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1403 // the exception consists of creating the exception object & initializing it, initialization
1404 // will leave the VM via a JavaCall and then all locks must be unlocked).
1406 // The thread is still suspended when we reach here. Thread must be explicit started
1407 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1408 // by calling Threads:add. The reason why this is not done here, is because the thread
1409 // object must be fully initialized (take a look at JVM_Start)
1412 JavaThread::~JavaThread() {
1413 if (TraceThreadEvents) {
1414 tty->print_cr("terminate thread %p", this);
1417 // JSR166 -- return the parker to the free list
1418 Parker::Release(_parker);
1421 // Free any remaining previous UnrollBlock
1422 vframeArray* old_array = vframe_array_last();
1424 if (old_array != NULL) {
1425 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1426 old_array->set_unroll_block(NULL);
1431 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1432 if (deferred != NULL) {
1433 // This can only happen if thread is destroyed before deoptimization occurs.
1434 assert(deferred->length() != 0, "empty array!");
1436 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1437 deferred->remove_at(0);
1438 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1440 } while (deferred->length() != 0);
1444 // All Java related clean up happens in exit
1445 ThreadSafepointState::destroy(this);
1446 if (_thread_profiler != NULL) delete _thread_profiler;
1447 if (_thread_stat != NULL) delete _thread_stat;
1451 // The first routine called by a new Java thread
1452 void JavaThread::run() {
1453 // initialize thread-local alloc buffer related fields
1454 this->initialize_tlab();
1456 // used to test validitity of stack trace backs
1457 this->record_base_of_stack_pointer();
1459 // Record real stack base and size.
1460 this->record_stack_base_and_size();
1462 // Initialize thread local storage; set before calling MutexLocker
1463 this->initialize_thread_local_storage();
1465 this->create_stack_guard_pages();
1467 this->cache_global_variables();
1469 // Thread is now sufficient initialized to be handled by the safepoint code as being
1470 // in the VM. Change thread state from _thread_new to _thread_in_vm
1471 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1473 assert(JavaThread::current() == this, "sanity check");
1474 assert(!Thread::current()->owns_locks(), "sanity check");
1476 DTRACE_THREAD_PROBE(start, this);
1478 // This operation might block. We call that after all safepoint checks for a new thread has
1480 this->set_active_handles(JNIHandleBlock::allocate_block());
1482 if (JvmtiExport::should_post_thread_life()) {
1483 JvmtiExport::post_thread_start(this);
1486 // We call another function to do the rest so we are sure that the stack addresses used
1487 // from there will be lower than the stack base just computed
1488 thread_main_inner();
1490 // Note, thread is no longer valid at this point!
1494 void JavaThread::thread_main_inner() {
1495 assert(JavaThread::current() == this, "sanity check");
1496 assert(this->threadObj() != NULL, "just checking");
1498 // Execute thread entry point unless this thread has a pending exception
1499 // or has been stopped before starting.
1500 // Note: Due to JVM_StopThread we can have pending exceptions already!
1501 if (!this->has_pending_exception() &&
1502 !java_lang_Thread::is_stillborn(this->threadObj())) {
1503 HandleMark hm(this);
1504 this->entry_point()(this, this);
1507 DTRACE_THREAD_PROBE(stop, this);
1514 static void ensure_join(JavaThread* thread) {
1515 // We do not need to grap the Threads_lock, since we are operating on ourself.
1516 Handle threadObj(thread, thread->threadObj());
1517 assert(threadObj.not_null(), "java thread object must exist");
1518 ObjectLocker lock(threadObj, thread);
1519 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1520 thread->clear_pending_exception();
1521 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1522 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1523 // Clear the native thread instance - this makes isAlive return false and allows the join()
1524 // to complete once we've done the notify_all below
1525 java_lang_Thread::set_thread(threadObj(), NULL);
1526 lock.notify_all(thread);
1527 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1528 thread->clear_pending_exception();
1532 // For any new cleanup additions, please check to see if they need to be applied to
1533 // cleanup_failed_attach_current_thread as well.
1534 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1535 assert(this == JavaThread::current(), "thread consistency check");
1536 if (!InitializeJavaLangSystem) return;
1538 HandleMark hm(this);
1539 Handle uncaught_exception(this, this->pending_exception());
1540 this->clear_pending_exception();
1541 Handle threadObj(this, this->threadObj());
1542 assert(threadObj.not_null(), "Java thread object should be created");
1544 if (get_thread_profiler() != NULL) {
1545 get_thread_profiler()->disengage();
1547 get_thread_profiler()->print(get_thread_name());
1551 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1555 CLEAR_PENDING_EXCEPTION;
1557 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1558 // has to be fixed by a runtime query method
1559 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1560 // JSR-166: change call from from ThreadGroup.uncaughtException to
1561 // java.lang.Thread.dispatchUncaughtException
1562 if (uncaught_exception.not_null()) {
1563 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1564 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1565 (address)uncaught_exception(), (address)threadObj(), (address)group());
1568 // Check if the method Thread.dispatchUncaughtException() exists. If so
1569 // call it. Otherwise we have an older library without the JSR-166 changes,
1570 // so call ThreadGroup.uncaughtException()
1571 KlassHandle recvrKlass(THREAD, threadObj->klass());
1573 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1574 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1575 vmSymbols::dispatchUncaughtException_name(),
1576 vmSymbols::throwable_void_signature(),
1577 KlassHandle(), false, false, THREAD);
1578 CLEAR_PENDING_EXCEPTION;
1579 methodHandle method = callinfo.selected_method();
1580 if (method.not_null()) {
1581 JavaValue result(T_VOID);
1582 JavaCalls::call_virtual(&result,
1583 threadObj, thread_klass,
1584 vmSymbols::dispatchUncaughtException_name(),
1585 vmSymbols::throwable_void_signature(),
1589 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1590 JavaValue result(T_VOID);
1591 JavaCalls::call_virtual(&result,
1592 group, thread_group,
1593 vmSymbols::uncaughtException_name(),
1594 vmSymbols::thread_throwable_void_signature(),
1596 uncaught_exception, // Arg 2
1599 if (HAS_PENDING_EXCEPTION) {
1600 ResourceMark rm(this);
1601 jio_fprintf(defaultStream::error_stream(),
1602 "\nException: %s thrown from the UncaughtExceptionHandler"
1603 " in thread \"%s\"\n",
1604 Klass::cast(pending_exception()->klass())->external_name(),
1606 CLEAR_PENDING_EXCEPTION;
1611 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1612 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1613 // is deprecated anyhow.
1615 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1617 JavaValue result(T_VOID);
1618 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1619 JavaCalls::call_virtual(&result,
1620 threadObj, thread_klass,
1621 vmSymbols::exit_method_name(),
1622 vmSymbols::void_method_signature(),
1624 CLEAR_PENDING_EXCEPTION;
1629 if (JvmtiExport::should_post_thread_life()) {
1630 JvmtiExport::post_thread_end(this);
1633 // We have notified the agents that we are exiting, before we go on,
1634 // we must check for a pending external suspend request and honor it
1635 // in order to not surprise the thread that made the suspend request.
1638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1639 if (!is_external_suspend()) {
1640 set_terminated(_thread_exiting);
1641 ThreadService::current_thread_exiting(this);
1645 // Things get a little tricky here. We have a pending external
1646 // suspend request, but we are holding the SR_lock so we
1647 // can't just self-suspend. So we temporarily drop the lock
1648 // and then self-suspend.
1651 ThreadBlockInVM tbivm(this);
1652 java_suspend_self();
1654 // We're done with this suspend request, but we have to loop around
1655 // and check again. Eventually we will get SR_lock without a pending
1656 // external suspend request and will be able to mark ourselves as
1659 // no more external suspends are allowed at this point
1661 // before_exit() has already posted JVMTI THREAD_END events
1664 // Notify waiters on thread object. This has to be done after exit() is called
1665 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1666 // group should have the destroyed bit set before waiters are notified).
1668 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1670 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1671 // held by this thread must be released. A detach operation must only
1672 // get here if there are no Java frames on the stack. Therefore, any
1673 // owned monitors at this point MUST be JNI-acquired monitors which are
1674 // pre-inflated and in the monitor cache.
1676 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1677 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1678 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1679 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1680 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1683 // These things needs to be done while we are still a Java Thread. Make sure that thread
1684 // is in a consistent state, in case GC happens
1685 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1687 if (active_handles() != NULL) {
1688 JNIHandleBlock* block = active_handles();
1689 set_active_handles(NULL);
1690 JNIHandleBlock::release_block(block);
1693 if (free_handle_block() != NULL) {
1694 JNIHandleBlock* block = free_handle_block();
1695 set_free_handle_block(NULL);
1696 JNIHandleBlock::release_block(block);
1699 // These have to be removed while this is still a valid thread.
1700 remove_stack_guard_pages();
1703 tlab().make_parsable(true); // retire TLAB
1706 if (JvmtiEnv::environments_might_exist()) {
1707 JvmtiExport::cleanup_thread(this);
1711 // We must flush G1-related buffers before removing a thread from
1712 // the list of active threads.
1714 flush_barrier_queues();
1718 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1719 Threads::remove(this);
1723 // Flush G1-related queues.
1724 void JavaThread::flush_barrier_queues() {
1725 satb_mark_queue().flush();
1726 dirty_card_queue().flush();
1729 void JavaThread::initialize_queues() {
1730 assert(!SafepointSynchronize::is_at_safepoint(),
1731 "we should not be at a safepoint");
1733 ObjPtrQueue& satb_queue = satb_mark_queue();
1734 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1735 // The SATB queue should have been constructed with its active
1736 // field set to false.
1737 assert(!satb_queue.is_active(), "SATB queue should not be active");
1738 assert(satb_queue.is_empty(), "SATB queue should be empty");
1739 // If we are creating the thread during a marking cycle, we should
1740 // set the active field of the SATB queue to true.
1741 if (satb_queue_set.is_active()) {
1742 satb_queue.set_active(true);
1745 DirtyCardQueue& dirty_queue = dirty_card_queue();
1746 // The dirty card queue should have been constructed with its
1747 // active field set to true.
1748 assert(dirty_queue.is_active(), "dirty card queue should be active");
1752 void JavaThread::cleanup_failed_attach_current_thread() {
1753 if (get_thread_profiler() != NULL) {
1754 get_thread_profiler()->disengage();
1756 get_thread_profiler()->print(get_thread_name());
1759 if (active_handles() != NULL) {
1760 JNIHandleBlock* block = active_handles();
1761 set_active_handles(NULL);
1762 JNIHandleBlock::release_block(block);
1765 if (free_handle_block() != NULL) {
1766 JNIHandleBlock* block = free_handle_block();
1767 set_free_handle_block(NULL);
1768 JNIHandleBlock::release_block(block);
1771 // These have to be removed while this is still a valid thread.
1772 remove_stack_guard_pages();
1775 tlab().make_parsable(true); // retire TLAB, if any
1780 flush_barrier_queues();
1784 Threads::remove(this);
1791 JavaThread* JavaThread::active() {
1792 Thread* thread = ThreadLocalStorage::thread();
1793 assert(thread != NULL, "just checking");
1794 if (thread->is_Java_thread()) {
1795 return (JavaThread*) thread;
1797 assert(thread->is_VM_thread(), "this must be a vm thread");
1798 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1799 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1800 assert(ret->is_Java_thread(), "must be a Java thread");
1805 bool JavaThread::is_lock_owned(address adr) const {
1806 if (Thread::is_lock_owned(adr)) return true;
1808 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1809 if (chunk->contains(adr)) return true;
1816 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1817 chunk->set_next(monitor_chunks());
1818 set_monitor_chunks(chunk);
1821 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1822 guarantee(monitor_chunks() != NULL, "must be non empty");
1823 if (monitor_chunks() == chunk) {
1824 set_monitor_chunks(chunk->next());
1826 MonitorChunk* prev = monitor_chunks();
1827 while (prev->next() != chunk) prev = prev->next();
1828 prev->set_next(chunk->next());
1834 // Note: this function shouldn't block if it's called in
1835 // _thread_in_native_trans state (such as from
1836 // check_special_condition_for_native_trans()).
1837 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1839 if (has_last_Java_frame() && has_async_condition()) {
1840 // If we are at a polling page safepoint (not a poll return)
1841 // then we must defer async exception because live registers
1842 // will be clobbered by the exception path. Poll return is
1843 // ok because the call we a returning from already collides
1844 // with exception handling registers and so there is no issue.
1845 // (The exception handling path kills call result registers but
1846 // this is ok since the exception kills the result anyway).
1848 if (is_at_poll_safepoint()) {
1849 // if the code we are returning to has deoptimized we must defer
1850 // the exception otherwise live registers get clobbered on the
1851 // exception path before deoptimization is able to retrieve them.
1853 RegisterMap map(this, false);
1854 frame caller_fr = last_frame().sender(&map);
1855 assert(caller_fr.is_compiled_frame(), "what?");
1856 if (caller_fr.is_deoptimized_frame()) {
1857 if (TraceExceptions) {
1859 tty->print_cr("deferred async exception at compiled safepoint");
1866 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1867 if (condition == _no_async_condition) {
1868 // Conditions have changed since has_special_runtime_exit_condition()
1870 // - if we were here only because of an external suspend request,
1871 // then that was taken care of above (or cancelled) so we are done
1872 // - if we were here because of another async request, then it has
1873 // been cleared between the has_special_runtime_exit_condition()
1874 // and now so again we are done
1878 // Check for pending async. exception
1879 if (_pending_async_exception != NULL) {
1880 // Only overwrite an already pending exception, if it is not a threadDeath.
1881 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1883 // We cannot call Exceptions::_throw(...) here because we cannot block
1884 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1886 if (TraceExceptions) {
1888 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1889 if (has_last_Java_frame() ) {
1890 frame f = last_frame();
1891 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1893 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1895 _pending_async_exception = NULL;
1896 clear_has_async_exception();
1900 if (check_unsafe_error &&
1901 condition == _async_unsafe_access_error && !has_pending_exception()) {
1902 condition = _no_async_condition; // done
1903 switch (thread_state()) {
1906 JavaThread* THREAD = this;
1907 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1909 case _thread_in_native:
1911 ThreadInVMfromNative tiv(this);
1912 JavaThread* THREAD = this;
1913 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1915 case _thread_in_Java:
1917 ThreadInVMfromJava tiv(this);
1918 JavaThread* THREAD = this;
1919 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1922 ShouldNotReachHere();
1926 assert(condition == _no_async_condition || has_pending_exception() ||
1927 (!check_unsafe_error && condition == _async_unsafe_access_error),
1928 "must have handled the async condition, if no exception");
1931 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1933 // Check for pending external suspend. Internal suspend requests do
1934 // not use handle_special_runtime_exit_condition().
1935 // If JNIEnv proxies are allowed, don't self-suspend if the target
1936 // thread is not the current thread. In older versions of jdbx, jdbx
1937 // threads could call into the VM with another thread's JNIEnv so we
1938 // can be here operating on behalf of a suspended thread (4432884).
1939 bool do_self_suspend = is_external_suspend_with_lock();
1940 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1942 // Because thread is external suspended the safepoint code will count
1943 // thread as at a safepoint. This can be odd because we can be here
1944 // as _thread_in_Java which would normally transition to _thread_blocked
1945 // at a safepoint. We would like to mark the thread as _thread_blocked
1946 // before calling java_suspend_self like all other callers of it but
1947 // we must then observe proper safepoint protocol. (We can't leave
1948 // _thread_blocked with a safepoint in progress). However we can be
1949 // here as _thread_in_native_trans so we can't use a normal transition
1950 // constructor/destructor pair because they assert on that type of
1951 // transition. We could do something like:
1953 // JavaThreadState state = thread_state();
1954 // set_thread_state(_thread_in_vm);
1956 // ThreadBlockInVM tbivm(this);
1957 // java_suspend_self()
1959 // set_thread_state(_thread_in_vm_trans);
1960 // if (safepoint) block;
1961 // set_thread_state(state);
1963 // but that is pretty messy. Instead we just go with the way the
1964 // code has worked before and note that this is the only path to
1965 // java_suspend_self that doesn't put the thread in _thread_blocked
1968 frame_anchor()->make_walkable(this);
1969 java_suspend_self();
1971 // We might be here for reasons in addition to the self-suspend request
1972 // so check for other async requests.
1976 check_and_handle_async_exceptions();
1980 void JavaThread::send_thread_stop(oop java_throwable) {
1981 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1982 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1983 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1985 // Do not throw asynchronous exceptions against the compiler thread
1986 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1987 if (is_Compiler_thread()) return;
1990 // Actually throw the Throwable against the target Thread - however
1991 // only if there is no thread death exception installed already.
1992 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1993 // If the topmost frame is a runtime stub, then we are calling into
1994 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1995 // must deoptimize the caller before continuing, as the compiled exception handler table
1997 if (has_last_Java_frame()) {
1998 frame f = last_frame();
1999 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2000 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2001 RegisterMap reg_map(this, UseBiasedLocking);
2002 frame compiled_frame = f.sender(®_map);
2003 if (compiled_frame.can_be_deoptimized()) {
2004 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2009 // Set async. pending exception in thread.
2010 set_pending_async_exception(java_throwable);
2012 if (TraceExceptions) {
2014 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2016 // for AbortVMOnException flag
2017 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2022 // Interrupt thread so it will wake up from a potential wait()
2023 Thread::interrupt(this);
2026 // External suspension mechanism.
2028 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2029 // to any VM_locks and it is at a transition
2030 // Self-suspension will happen on the transition out of the vm.
2031 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2033 // Guarantees on return:
2034 // + Target thread will not execute any new bytecode (that's why we need to
2035 // force a safepoint)
2036 // + Target thread will not enter any new monitors
2038 void JavaThread::java_suspend() {
2039 { MutexLocker mu(Threads_lock);
2040 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2045 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2046 if (!is_external_suspend()) {
2047 // a racing resume has cancelled us; bail out now
2052 uint32_t debug_bits = 0;
2053 // Warning: is_ext_suspend_completed() may temporarily drop the
2054 // SR_lock to allow the thread to reach a stable thread state if
2055 // it is currently in a transient thread state.
2056 if (is_ext_suspend_completed(false /* !called_by_wait */,
2057 SuspendRetryDelay, &debug_bits) ) {
2062 VM_ForceSafepoint vm_suspend;
2063 VMThread::execute(&vm_suspend);
2066 // Part II of external suspension.
2067 // A JavaThread self suspends when it detects a pending external suspend
2068 // request. This is usually on transitions. It is also done in places
2069 // where continuing to the next transition would surprise the caller,
2070 // e.g., monitor entry.
2072 // Returns the number of times that the thread self-suspended.
2074 // Note: DO NOT call java_suspend_self() when you just want to block current
2075 // thread. java_suspend_self() is the second stage of cooperative
2076 // suspension for external suspend requests and should only be used
2077 // to complete an external suspend request.
2079 int JavaThread::java_suspend_self() {
2082 // we are in the process of exiting so don't suspend
2084 clear_external_suspend();
2088 assert(_anchor.walkable() ||
2089 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2090 "must have walkable stack");
2092 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2094 assert(!this->is_ext_suspended(),
2095 "a thread trying to self-suspend should not already be suspended");
2097 if (this->is_suspend_equivalent()) {
2098 // If we are self-suspending as a result of the lifting of a
2099 // suspend equivalent condition, then the suspend_equivalent
2100 // flag is not cleared until we set the ext_suspended flag so
2101 // that wait_for_ext_suspend_completion() returns consistent
2103 this->clear_suspend_equivalent();
2106 // A racing resume may have cancelled us before we grabbed SR_lock
2107 // above. Or another external suspend request could be waiting for us
2108 // by the time we return from SR_lock()->wait(). The thread
2109 // that requested the suspension may already be trying to walk our
2110 // stack and if we return now, we can change the stack out from under
2111 // it. This would be a "bad thing (TM)" and cause the stack walker
2112 // to crash. We stay self-suspended until there are no more pending
2113 // external suspend requests.
2114 while (is_external_suspend()) {
2116 this->set_ext_suspended();
2118 // _ext_suspended flag is cleared by java_resume()
2119 while (is_ext_suspended()) {
2120 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2128 // verify the JavaThread has not yet been published in the Threads::list, and
2129 // hence doesn't need protection from concurrent access at this stage
2130 void JavaThread::verify_not_published() {
2131 if (!Threads_lock->owned_by_self()) {
2132 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2133 assert( !Threads::includes(this),
2134 "java thread shouldn't have been published yet!");
2137 assert( !Threads::includes(this),
2138 "java thread shouldn't have been published yet!");
2143 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2144 // progress or when _suspend_flags is non-zero.
2145 // Current thread needs to self-suspend if there is a suspend request and/or
2146 // block if a safepoint is in progress.
2147 // Async exception ISN'T checked.
2148 // Note only the ThreadInVMfromNative transition can call this function
2149 // directly and when thread state is _thread_in_native_trans
2150 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2151 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2153 JavaThread *curJT = JavaThread::current();
2154 bool do_self_suspend = thread->is_external_suspend();
2156 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2158 // If JNIEnv proxies are allowed, don't self-suspend if the target
2159 // thread is not the current thread. In older versions of jdbx, jdbx
2160 // threads could call into the VM with another thread's JNIEnv so we
2161 // can be here operating on behalf of a suspended thread (4432884).
2162 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2163 JavaThreadState state = thread->thread_state();
2165 // We mark this thread_blocked state as a suspend-equivalent so
2166 // that a caller to is_ext_suspend_completed() won't be confused.
2167 // The suspend-equivalent state is cleared by java_suspend_self().
2168 thread->set_suspend_equivalent();
2170 // If the safepoint code sees the _thread_in_native_trans state, it will
2171 // wait until the thread changes to other thread state. There is no
2172 // guarantee on how soon we can obtain the SR_lock and complete the
2173 // self-suspend request. It would be a bad idea to let safepoint wait for
2174 // too long. Temporarily change the state to _thread_blocked to
2175 // let the VM thread know that this thread is ready for GC. The problem
2176 // of changing thread state is that safepoint could happen just after
2177 // java_suspend_self() returns after being resumed, and VM thread will
2178 // see the _thread_blocked state. We must check for safepoint
2179 // after restoring the state and make sure we won't leave while a safepoint
2181 thread->set_thread_state(_thread_blocked);
2182 thread->java_suspend_self();
2183 thread->set_thread_state(state);
2184 // Make sure new state is seen by VM thread
2187 // Force a fence between the write above and read below
2188 OrderAccess::fence();
2190 // Must use this rather than serialization page in particular on Windows
2191 InterfaceSupport::serialize_memory(thread);
2196 if (SafepointSynchronize::do_call_back()) {
2197 // If we are safepointing, then block the caller which may not be
2198 // the same as the target thread (see above).
2199 SafepointSynchronize::block(curJT);
2202 if (thread->is_deopt_suspend()) {
2203 thread->clear_deopt_suspend();
2204 RegisterMap map(thread, false);
2205 frame f = thread->last_frame();
2206 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2209 if (f.id() == thread->must_deopt_id()) {
2210 thread->clear_must_deopt_id();
2211 f.deoptimize(thread);
2213 fatal("missed deoptimization!");
2218 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2219 // progress or when _suspend_flags is non-zero.
2220 // Current thread needs to self-suspend if there is a suspend request and/or
2221 // block if a safepoint is in progress.
2222 // Also check for pending async exception (not including unsafe access error).
2223 // Note only the native==>VM/Java barriers can call this function and when
2224 // thread state is _thread_in_native_trans.
2225 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2226 check_safepoint_and_suspend_for_native_trans(thread);
2228 if (thread->has_async_exception()) {
2229 // We are in _thread_in_native_trans state, don't handle unsafe
2230 // access error since that may block.
2231 thread->check_and_handle_async_exceptions(false);
2235 // We need to guarantee the Threads_lock here, since resumes are not
2236 // allowed during safepoint synchronization
2237 // Can only resume from an external suspension
2238 void JavaThread::java_resume() {
2239 assert_locked_or_safepoint(Threads_lock);
2241 // Sanity check: thread is gone, has started exiting or the thread
2242 // was not externally suspended.
2243 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2247 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2249 clear_external_suspend();
2251 if (is_ext_suspended()) {
2252 clear_ext_suspended();
2253 SR_lock()->notify_all();
2257 void JavaThread::create_stack_guard_pages() {
2258 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2259 address low_addr = stack_base() - stack_size();
2260 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2262 int allocate = os::allocate_stack_guard_pages();
2263 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2265 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2266 warning("Attempt to allocate stack guard pages failed.");
2270 if (os::guard_memory((char *) low_addr, len)) {
2271 _stack_guard_state = stack_guard_enabled;
2273 warning("Attempt to protect stack guard pages failed.");
2274 if (os::uncommit_memory((char *) low_addr, len)) {
2275 warning("Attempt to deallocate stack guard pages failed.");
2280 void JavaThread::remove_stack_guard_pages() {
2281 if (_stack_guard_state == stack_guard_unused) return;
2282 address low_addr = stack_base() - stack_size();
2283 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2285 if (os::allocate_stack_guard_pages()) {
2286 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2287 _stack_guard_state = stack_guard_unused;
2289 warning("Attempt to deallocate stack guard pages failed.");
2292 if (_stack_guard_state == stack_guard_unused) return;
2293 if (os::unguard_memory((char *) low_addr, len)) {
2294 _stack_guard_state = stack_guard_unused;
2296 warning("Attempt to unprotect stack guard pages failed.");
2301 void JavaThread::enable_stack_yellow_zone() {
2302 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2303 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2305 // The base notation is from the stacks point of view, growing downward.
2306 // We need to adjust it to work correctly with guard_memory()
2307 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2309 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2310 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2312 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2313 _stack_guard_state = stack_guard_enabled;
2315 warning("Attempt to guard stack yellow zone failed.");
2317 enable_register_stack_guard();
2320 void JavaThread::disable_stack_yellow_zone() {
2321 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2322 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2324 // Simply return if called for a thread that does not use guard pages.
2325 if (_stack_guard_state == stack_guard_unused) return;
2327 // The base notation is from the stacks point of view, growing downward.
2328 // We need to adjust it to work correctly with guard_memory()
2329 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2331 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2332 _stack_guard_state = stack_guard_yellow_disabled;
2334 warning("Attempt to unguard stack yellow zone failed.");
2336 disable_register_stack_guard();
2339 void JavaThread::enable_stack_red_zone() {
2340 // The base notation is from the stacks point of view, growing downward.
2341 // We need to adjust it to work correctly with guard_memory()
2342 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2343 address base = stack_red_zone_base() - stack_red_zone_size();
2345 guarantee(base < stack_base(),"Error calculating stack red zone");
2346 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2348 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2349 warning("Attempt to guard stack red zone failed.");
2353 void JavaThread::disable_stack_red_zone() {
2354 // The base notation is from the stacks point of view, growing downward.
2355 // We need to adjust it to work correctly with guard_memory()
2356 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2357 address base = stack_red_zone_base() - stack_red_zone_size();
2358 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2359 warning("Attempt to unguard stack red zone failed.");
2363 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2364 // ignore is there is no stack
2365 if (!has_last_Java_frame()) return;
2366 // traverse the stack frames. Starts from top frame.
2367 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2368 frame* fr = fst.current();
2369 f(fr, fst.register_map());
2376 // Function for testing deoptimization
2377 void JavaThread::deoptimize() {
2378 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2379 StackFrameStream fst(this, UseBiasedLocking);
2380 bool deopt = false; // Dump stack only if a deopt actually happens.
2381 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2382 // Iterate over all frames in the thread and deoptimize
2383 for(; !fst.is_done(); fst.next()) {
2384 if(fst.current()->can_be_deoptimized()) {
2387 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2388 // consists of comma or carriage return separated numbers so
2389 // search for the current bci in that string.
2390 address pc = fst.current()->pc();
2391 nmethod* nm = (nmethod*) fst.current()->cb();
2392 ScopeDesc* sd = nm->scope_desc_at( pc);
2394 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2395 size_t len = strlen(buffer);
2396 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2397 while (found != NULL) {
2398 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2399 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2400 // Check that the bci found is bracketed by terminators.
2403 found = strstr(found + 1, buffer);
2410 if (DebugDeoptimization && !deopt) {
2411 deopt = true; // One-time only print before deopt
2412 tty->print_cr("[BEFORE Deoptimization]");
2416 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2420 if (DebugDeoptimization && deopt) {
2421 tty->print_cr("[AFTER Deoptimization]");
2428 void JavaThread::make_zombies() {
2429 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2430 if (fst.current()->can_be_deoptimized()) {
2431 // it is a Java nmethod
2432 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2433 nm->make_not_entrant();
2440 void JavaThread::deoptimized_wrt_marked_nmethods() {
2441 if (!has_last_Java_frame()) return;
2442 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2443 StackFrameStream fst(this, UseBiasedLocking);
2444 for(; !fst.is_done(); fst.next()) {
2445 if (fst.current()->should_be_deoptimized()) {
2446 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2453 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2455 void JavaThread::gc_epilogue() {
2456 frames_do(frame_gc_epilogue);
2460 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2462 void JavaThread::gc_prologue() {
2463 frames_do(frame_gc_prologue);
2466 // If the caller is a NamedThread, then remember, in the current scope,
2467 // the given JavaThread in its _processed_thread field.
2468 class RememberProcessedThread: public StackObj {
2469 NamedThread* _cur_thr;
2471 RememberProcessedThread(JavaThread* jthr) {
2472 Thread* thread = Thread::current();
2473 if (thread->is_Named_thread()) {
2474 _cur_thr = (NamedThread *)thread;
2475 _cur_thr->set_processed_thread(jthr);
2481 ~RememberProcessedThread() {
2483 _cur_thr->set_processed_thread(NULL);
2488 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2489 // Verify that the deferred card marks have been flushed.
2490 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2492 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2493 // since there may be more than one thread using each ThreadProfiler.
2495 // Traverse the GCHandles
2496 Thread::oops_do(f, cf);
2498 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2499 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2501 if (has_last_Java_frame()) {
2502 // Record JavaThread to GC thread
2503 RememberProcessedThread rpt(this);
2505 // Traverse the privileged stack
2506 if (_privileged_stack_top != NULL) {
2507 _privileged_stack_top->oops_do(f);
2510 // traverse the registered growable array
2511 if (_array_for_gc != NULL) {
2512 for (int index = 0; index < _array_for_gc->length(); index++) {
2513 f->do_oop(_array_for_gc->adr_at(index));
2517 // Traverse the monitor chunks
2518 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2522 // Traverse the execution stack
2523 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2524 fst.current()->oops_do(f, cf, fst.register_map());
2528 // callee_target is never live across a gc point so NULL it here should
2529 // it still contain a methdOop.
2531 set_callee_target(NULL);
2533 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2534 // If we have deferred set_locals there might be oops waiting to be
2536 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2538 for (int i = 0; i < list->length(); i++) {
2539 list->at(i)->oops_do(f);
2543 // Traverse instance variables at the end since the GC may be moving things
2544 // around using this function
2545 f->do_oop((oop*) &_threadObj);
2546 f->do_oop((oop*) &_vm_result);
2547 f->do_oop((oop*) &_vm_result_2);
2548 f->do_oop((oop*) &_exception_oop);
2549 f->do_oop((oop*) &_pending_async_exception);
2551 if (jvmti_thread_state() != NULL) {
2552 jvmti_thread_state()->oops_do(f);
2556 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2557 Thread::nmethods_do(cf); // (super method is a no-op)
2559 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2560 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2562 if (has_last_Java_frame()) {
2563 // Traverse the execution stack
2564 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2565 fst.current()->nmethods_do(cf);
2571 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2572 switch (_thread_state) {
2573 case _thread_uninitialized: return "_thread_uninitialized";
2574 case _thread_new: return "_thread_new";
2575 case _thread_new_trans: return "_thread_new_trans";
2576 case _thread_in_native: return "_thread_in_native";
2577 case _thread_in_native_trans: return "_thread_in_native_trans";
2578 case _thread_in_vm: return "_thread_in_vm";
2579 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2580 case _thread_in_Java: return "_thread_in_Java";
2581 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2582 case _thread_blocked: return "_thread_blocked";
2583 case _thread_blocked_trans: return "_thread_blocked_trans";
2584 default: return "unknown thread state";
2589 void JavaThread::print_thread_state_on(outputStream *st) const {
2590 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2592 void JavaThread::print_thread_state() const {
2593 print_thread_state_on(tty);
2597 // Called by Threads::print() for VM_PrintThreads operation
2598 void JavaThread::print_on(outputStream *st) const {
2599 st->print("\"%s\" ", get_thread_name());
2600 oop thread_oop = threadObj();
2601 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2602 Thread::print_on(st);
2603 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2604 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2605 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2606 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2609 print_thread_state_on(st);
2610 _safepoint_state->print_on(st);
2614 // Called by fatal error handler. The difference between this and
2615 // JavaThread::print() is that we can't grab lock or allocate memory.
2616 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2617 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2618 oop thread_obj = threadObj();
2619 if (thread_obj != NULL) {
2620 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2623 st->print("%s", _get_thread_state_name(_thread_state));
2625 st->print(", id=%d", osthread()->thread_id());
2627 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2628 _stack_base - _stack_size, _stack_base);
2635 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2637 void JavaThread::verify() {
2638 // Verify oops in the thread.
2639 oops_do(&VerifyOopClosure::verify_oop, NULL);
2641 // Verify the stack frames.
2642 frames_do(frame_verify);
2645 // CR 6300358 (sub-CR 2137150)
2646 // Most callers of this method assume that it can't return NULL but a
2647 // thread may not have a name whilst it is in the process of attaching to
2648 // the VM - see CR 6412693, and there are places where a JavaThread can be
2649 // seen prior to having it's threadObj set (eg JNI attaching threads and
2650 // if vm exit occurs during initialization). These cases can all be accounted
2651 // for such that this method never returns NULL.
2652 const char* JavaThread::get_thread_name() const {
2654 // early safepoints can hit while current thread does not yet have TLS
2655 if (!SafepointSynchronize::is_at_safepoint()) {
2656 Thread *cur = Thread::current();
2657 if (!(cur->is_Java_thread() && cur == this)) {
2658 // Current JavaThreads are allowed to get their own name without
2659 // the Threads_lock.
2660 assert_locked_or_safepoint(Threads_lock);
2664 return get_thread_name_string();
2667 // Returns a non-NULL representation of this thread's name, or a suitable
2668 // descriptive string if there is no set name
2669 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2670 const char* name_str;
2671 oop thread_obj = threadObj();
2672 if (thread_obj != NULL) {
2673 typeArrayOop name = java_lang_Thread::name(thread_obj);
2676 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2679 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2682 else if (is_attaching()) { // workaround for 6412693 - see 6404306
2683 name_str = "<no-name - thread is attaching>";
2686 name_str = Thread::name();
2690 name_str = Thread::name();
2692 assert(name_str != NULL, "unexpected NULL thread name");
2697 const char* JavaThread::get_threadgroup_name() const {
2698 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2699 oop thread_obj = threadObj();
2700 if (thread_obj != NULL) {
2701 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2702 if (thread_group != NULL) {
2703 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2704 // ThreadGroup.name can be null
2706 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2714 const char* JavaThread::get_parent_name() const {
2715 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2716 oop thread_obj = threadObj();
2717 if (thread_obj != NULL) {
2718 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2719 if (thread_group != NULL) {
2720 oop parent = java_lang_ThreadGroup::parent(thread_group);
2721 if (parent != NULL) {
2722 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2723 // ThreadGroup.name can be null
2725 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2734 ThreadPriority JavaThread::java_priority() const {
2735 oop thr_oop = threadObj();
2736 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2737 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2738 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2742 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2744 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2745 // Link Java Thread object <-> C++ Thread
2747 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2748 // and put it into a new Handle. The Handle "thread_oop" can then
2749 // be used to pass the C++ thread object to other methods.
2751 // Set the Java level thread object (jthread) field of the
2752 // new thread (a JavaThread *) to C++ thread object using the
2753 // "thread_oop" handle.
2755 // Set the thread field (a JavaThread *) of the
2756 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2758 Handle thread_oop(Thread::current(),
2759 JNIHandles::resolve_non_null(jni_thread));
2760 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2761 "must be initialized");
2762 set_threadObj(thread_oop());
2763 java_lang_Thread::set_thread(thread_oop(), this);
2765 if (prio == NoPriority) {
2766 prio = java_lang_Thread::priority(thread_oop());
2767 assert(prio != NoPriority, "A valid priority should be present");
2770 // Push the Java priority down to the native thread; needs Threads_lock
2771 Thread::set_priority(this, prio);
2773 // Add the new thread to the Threads list and set it in motion.
2774 // We must have threads lock in order to call Threads::add.
2775 // It is crucial that we do not block before the thread is
2776 // added to the Threads list for if a GC happens, then the java_thread oop
2777 // will not be visited by GC.
2781 oop JavaThread::current_park_blocker() {
2782 // Support for JSR-166 locks
2783 oop thread_oop = threadObj();
2784 if (thread_oop != NULL &&
2785 JDK_Version::current().supports_thread_park_blocker()) {
2786 return java_lang_Thread::park_blocker(thread_oop);
2792 void JavaThread::print_stack_on(outputStream* st) {
2793 if (!has_last_Java_frame()) return;
2797 RegisterMap reg_map(this);
2798 vframe* start_vf = last_java_vframe(®_map);
2800 for (vframe* f = start_vf; f; f = f->sender() ) {
2801 if (f->is_java_frame()) {
2802 javaVFrame* jvf = javaVFrame::cast(f);
2803 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2805 // Print out lock information
2806 if (JavaMonitorsInStackTrace) {
2807 jvf->print_lock_info_on(st, count);
2810 // Ignore non-Java frames
2813 // Bail-out case for too deep stacks
2815 if (MaxJavaStackTraceDepth == count) return;
2820 // JVMTI PopFrame support
2821 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2822 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2823 if (in_bytes(size_in_bytes) != 0) {
2824 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2825 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2826 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2830 void* JavaThread::popframe_preserved_args() {
2831 return _popframe_preserved_args;
2834 ByteSize JavaThread::popframe_preserved_args_size() {
2835 return in_ByteSize(_popframe_preserved_args_size);
2838 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2839 int sz = in_bytes(popframe_preserved_args_size());
2840 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2841 return in_WordSize(sz / wordSize);
2844 void JavaThread::popframe_free_preserved_args() {
2845 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2846 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2847 _popframe_preserved_args = NULL;
2848 _popframe_preserved_args_size = 0;
2853 void JavaThread::trace_frames() {
2854 tty->print_cr("[Describe stack]");
2856 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2857 tty->print(" %d. ", frame_no++);
2858 fst.current()->print_value_on(tty,this);
2865 // Print or validate the layout of stack frames
2866 void JavaThread::print_frame_layout(int depth, bool validate_only) {
2868 PRESERVE_EXCEPTION_MARK;
2871 for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
2872 fst.current()->describe(values, ++frame_no);
2873 if (depth == frame_no) break;
2875 if (validate_only) {
2878 tty->print_cr("[Describe stack layout]");
2884 void JavaThread::trace_stack_from(vframe* start_vf) {
2887 for (vframe* f = start_vf; f; f = f->sender() ) {
2888 if (f->is_java_frame()) {
2889 javaVFrame::cast(f)->print_activation(vframe_no++);
2893 if (vframe_no > StackPrintLimit) {
2894 tty->print_cr("...<more frames>...");
2901 void JavaThread::trace_stack() {
2902 if (!has_last_Java_frame()) return;
2905 RegisterMap reg_map(this);
2906 trace_stack_from(last_java_vframe(®_map));
2913 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2914 assert(reg_map != NULL, "a map must be given");
2915 frame f = last_frame();
2916 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2917 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2923 klassOop JavaThread::security_get_caller_class(int depth) {
2924 vframeStream vfst(this);
2925 vfst.security_get_caller_frame(depth);
2926 if (!vfst.at_end()) {
2927 return vfst.method()->method_holder();
2932 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2933 assert(thread->is_Compiler_thread(), "must be compiler thread");
2934 CompileBroker::compiler_thread_loop();
2937 // Create a CompilerThread
2938 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2939 : JavaThread(&compiler_thread_entry) {
2944 _counters = counters;
2945 _buffer_blob = NULL;
2946 _scanned_nmethod = NULL;
2949 _ideal_graph_printer = NULL;
2953 void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2954 JavaThread::oops_do(f, cf);
2955 if (_scanned_nmethod != NULL && cf != NULL) {
2956 // Safepoints can occur when the sweeper is scanning an nmethod so
2957 // process it here to make sure it isn't unloaded in the middle of
2959 cf->do_code_blob(_scanned_nmethod);
2963 // ======= Threads ========
2965 // The Threads class links together all active threads, and provides
2966 // operations over all threads. It is protected by its own Mutex
2967 // lock, which is also used in other contexts to protect thread
2968 // operations from having the thread being operated on from exiting
2969 // and going away unexpectedly (e.g., safepoint synchronization)
2971 JavaThread* Threads::_thread_list = NULL;
2972 int Threads::_number_of_threads = 0;
2973 int Threads::_number_of_non_daemon_threads = 0;
2974 int Threads::_return_code = 0;
2975 size_t JavaThread::_stack_size_at_create = 0;
2978 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2982 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2983 void Threads::threads_do(ThreadClosure* tc) {
2984 assert_locked_or_safepoint(Threads_lock);
2985 // ALL_JAVA_THREADS iterates through all JavaThreads
2986 ALL_JAVA_THREADS(p) {
2989 // Someday we could have a table or list of all non-JavaThreads.
2990 // For now, just manually iterate through them.
2991 tc->do_thread(VMThread::vm_thread());
2992 Universe::heap()->gc_threads_do(tc);
2993 WatcherThread *wt = WatcherThread::watcher_thread();
2994 // Strictly speaking, the following NULL check isn't sufficient to make sure
2995 // the data for WatcherThread is still valid upon being examined. However,
2996 // considering that WatchThread terminates when the VM is on the way to
2997 // exit at safepoint, the chance of the above is extremely small. The right
2998 // way to prevent termination of WatcherThread would be to acquire
2999 // Terminator_lock, but we can't do that without violating the lock rank
3000 // checking in some cases.
3004 // If CompilerThreads ever become non-JavaThreads, add them here
3007 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3009 extern void JDK_Version_init();
3012 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3014 // Initialize the output stream module
3017 // Process java launcher properties.
3018 Arguments::process_sun_java_launcher_properties(args);
3020 // Initialize the os module before using TLS
3023 // Initialize system properties.
3024 Arguments::init_system_properties();
3026 // So that JDK version can be used as a discrimintor when parsing arguments
3029 // Update/Initialize System properties after JDK version number is known
3030 Arguments::init_version_specific_system_properties();
3033 jint parse_result = Arguments::parse(args);
3034 if (parse_result != JNI_OK) return parse_result;
3036 if (PauseAtStartup) {
3040 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3042 // Record VM creation timing statistics
3043 TraceVmCreationTime create_vm_timer;
3044 create_vm_timer.start();
3046 // Timing (must come after argument parsing)
3047 TraceTime timer("Create VM", TraceStartupTime);
3049 // Initialize the os module after parsing the args
3050 jint os_init_2_result = os::init_2();
3051 if (os_init_2_result != JNI_OK) return os_init_2_result;
3053 // Initialize output stream logging
3056 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3057 // Must be before create_vm_init_agents()
3058 if (Arguments::init_libraries_at_startup()) {
3059 convert_vm_init_libraries_to_agents();
3062 // Launch -agentlib/-agentpath and converted -Xrun agents
3063 if (Arguments::init_agents_at_startup()) {
3064 create_vm_init_agents();
3067 // Initialize Threads state
3068 _thread_list = NULL;
3069 _number_of_threads = 0;
3070 _number_of_non_daemon_threads = 0;
3073 ThreadLocalStorage::init();
3075 // Initialize global data structures and create system classes in heap
3078 // Attach the main thread to this os thread
3079 JavaThread* main_thread = new JavaThread();
3080 main_thread->set_thread_state(_thread_in_vm);
3081 // must do this before set_active_handles and initialize_thread_local_storage
3082 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3083 // change the stack size recorded here to one based on the java thread
3084 // stacksize. This adjusted size is what is used to figure the placement
3085 // of the guard pages.
3086 main_thread->record_stack_base_and_size();
3087 main_thread->initialize_thread_local_storage();
3089 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3091 if (!main_thread->set_as_starting_thread()) {
3092 vm_shutdown_during_initialization(
3093 "Failed necessary internal allocation. Out of swap space");
3095 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3099 // Enable guard page *after* os::create_main_thread(), otherwise it would
3100 // crash Linux VM, see notes in os_linux.cpp.
3101 main_thread->create_stack_guard_pages();
3103 // Initialize Java-Level synchronization subsystem
3104 ObjectMonitor::Initialize() ;
3106 // Initialize global modules
3107 jint status = init_globals();
3108 if (status != JNI_OK) {
3110 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3114 // Should be done after the heap is fully created
3115 main_thread->cache_global_variables();
3119 { MutexLocker mu(Threads_lock);
3120 Threads::add(main_thread);
3123 // Any JVMTI raw monitors entered in onload will transition into
3124 // real raw monitor. VM is setup enough here for raw monitor enter.
3125 JvmtiExport::transition_pending_onload_raw_monitors();
3127 if (VerifyBeforeGC &&
3128 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3129 Universe::heap()->prepare_for_verify();
3130 Universe::verify(); // make sure we're starting with a clean slate
3133 // Create the VMThread
3134 { TraceTime timer("Start VMThread", TraceStartupTime);
3136 Thread* vmthread = VMThread::vm_thread();
3138 if (!os::create_thread(vmthread, os::vm_thread))
3139 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3141 // Wait for the VM thread to become ready, and VMThread::run to initialize
3142 // Monitors can have spurious returns, must always check another state flag
3144 MutexLocker ml(Notify_lock);
3145 os::start_thread(vmthread);
3146 while (vmthread->active_handles() == NULL) {
3147 Notify_lock->wait();
3152 assert (Universe::is_fully_initialized(), "not initialized");
3155 // At this point, the Universe is initialized, but we have not executed
3156 // any byte code. Now is a good time (the only time) to dump out the
3157 // internal state of the JVM for sharing.
3159 if (DumpSharedSpaces) {
3160 Universe::heap()->preload_and_dump(CHECK_0);
3161 ShouldNotReachHere();
3164 // Always call even when there are not JVMTI environments yet, since environments
3165 // may be attached late and JVMTI must track phases of VM execution
3166 JvmtiExport::enter_start_phase();
3168 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3169 JvmtiExport::post_vm_start();
3172 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3174 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3175 create_vm_init_libraries();
3178 if (InitializeJavaLangString) {
3179 initialize_class(vmSymbols::java_lang_String(), CHECK_0);
3181 warning("java.lang.String not initialized");
3184 if (AggressiveOpts) {
3186 // Forcibly initialize java/util/HashMap and mutate the private
3187 // static final "frontCacheEnabled" field before we start creating instances
3189 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3190 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3192 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3193 KlassHandle k = KlassHandle(THREAD, k_o);
3194 guarantee(k.not_null(), "Must find java/util/HashMap");
3195 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3196 ik->initialize(CHECK_0);
3198 // Possible we might not find this field; if so, don't break
3199 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3200 k()->java_mirror()->bool_field_put(fd.offset(), true);
3204 if (UseStringCache) {
3205 // Forcibly initialize java/lang/StringValue and mutate the private
3206 // static final "stringCacheEnabled" field before we start creating instances
3207 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3208 // Possible that StringValue isn't present: if so, silently don't break
3210 KlassHandle k = KlassHandle(THREAD, k_o);
3211 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3212 ik->initialize(CHECK_0);
3214 // Possible we might not find this field: if so, silently don't break
3215 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3216 k()->java_mirror()->bool_field_put(fd.offset(), true);
3222 // Initialize java_lang.System (needed before creating the thread)
3223 if (InitializeJavaLangSystem) {
3224 initialize_class(vmSymbols::java_lang_System(), CHECK_0);
3225 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0);
3226 Handle thread_group = create_initial_thread_group(CHECK_0);
3227 Universe::set_main_thread_group(thread_group());
3228 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0);
3229 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3230 main_thread->set_threadObj(thread_object);
3231 // Set thread status to running since main thread has
3232 // been started and running.
3233 java_lang_Thread::set_thread_status(thread_object,
3234 java_lang_Thread::RUNNABLE);
3236 // The VM preresolve methods to these classes. Make sure that get initialized
3237 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0);
3238 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0);
3239 // The VM creates & returns objects of this class. Make sure it's initialized.
3240 initialize_class(vmSymbols::java_lang_Class(), CHECK_0);
3241 call_initializeSystemClass(CHECK_0);
3243 warning("java.lang.System not initialized");
3246 // an instance of OutOfMemory exception has been allocated earlier
3247 if (InitializeJavaLangExceptionsErrors) {
3248 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0);
3249 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0);
3250 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0);
3251 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0);
3252 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0);
3253 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0);
3254 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0);
3256 warning("java.lang.OutOfMemoryError has not been initialized");
3257 warning("java.lang.NullPointerException has not been initialized");
3258 warning("java.lang.ClassCastException has not been initialized");
3259 warning("java.lang.ArrayStoreException has not been initialized");
3260 warning("java.lang.ArithmeticException has not been initialized");
3261 warning("java.lang.StackOverflowError has not been initialized");
3265 // See : bugid 4211085.
3266 // Background : the static initializer of java.lang.Compiler tries to read
3267 // property"java.compiler" and read & write property "java.vm.info".
3268 // When a security manager is installed through the command line
3269 // option "-Djava.security.manager", the above properties are not
3270 // readable and the static initializer for java.lang.Compiler fails
3271 // resulting in a NoClassDefFoundError. This can happen in any
3272 // user code which calls methods in java.lang.Compiler.
3273 // Hack : the hack is to pre-load and initialize this class, so that only
3274 // system domains are on the stack when the properties are read.
3275 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3276 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3277 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3278 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3279 // Once that is done, we should remove this hack.
3280 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0);
3282 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3283 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3284 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3285 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3286 // This should also be taken out as soon as 4211383 gets fixed.
3287 reset_vm_info_property(CHECK_0);
3289 quicken_jni_functions();
3291 // Set flag that basic initialization has completed. Used by exceptions and various
3292 // debug stuff, that does not work until all basic classes have been initialized.
3293 set_init_completed();
3295 HS_DTRACE_PROBE(hotspot, vm__init__end);
3297 // record VM initialization completion time
3298 Management::record_vm_init_completed();
3300 // Compute system loader. Note that this has to occur after set_init_completed, since
3301 // valid exceptions may be thrown in the process.
3302 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3303 // set_init_completed has just been called, causing exceptions not to be shortcut
3304 // anymore. We call vm_exit_during_initialization directly instead.
3305 SystemDictionary::compute_java_system_loader(THREAD);
3306 if (HAS_PENDING_EXCEPTION) {
3307 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3311 // Support for ConcurrentMarkSweep. This should be cleaned up
3312 // and better encapsulated. The ugly nested if test would go away
3313 // once things are properly refactored. XXX YSR
3314 if (UseConcMarkSweepGC || UseG1GC) {
3315 if (UseConcMarkSweepGC) {
3316 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3318 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3320 if (HAS_PENDING_EXCEPTION) {
3321 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3326 // Always call even when there are not JVMTI environments yet, since environments
3327 // may be attached late and JVMTI must track phases of VM execution
3328 JvmtiExport::enter_live_phase();
3330 // Signal Dispatcher needs to be started before VMInit event is posted
3333 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3334 if (!DisableAttachMechanism) {
3335 if (StartAttachListener || AttachListener::init_at_startup()) {
3336 AttachListener::init();
3340 // Launch -Xrun agents
3341 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3342 // back-end can launch with -Xdebug -Xrunjdwp.
3343 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3344 create_vm_init_libraries();
3347 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3348 JvmtiExport::post_vm_initialized();
3350 Chunk::start_chunk_pool_cleaner_task();
3352 // initialize compiler(s)
3353 CompileBroker::compilation_init();
3355 Management::initialize(THREAD);
3356 if (HAS_PENDING_EXCEPTION) {
3357 // management agent fails to start possibly due to
3358 // configuration problem and is responsible for printing
3359 // stack trace if appropriate. Simply exit VM.
3363 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3364 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3365 if (MemProfiling) MemProfiler::engage();
3366 StatSampler::engage();
3367 if (CheckJNICalls) JniPeriodicChecker::engage();
3369 BiasedLocking::init();
3371 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3372 call_postVMInitHook(THREAD);
3373 // The Java side of PostVMInitHook.run must deal with all
3374 // exceptions and provide means of diagnosis.
3375 if (HAS_PENDING_EXCEPTION) {
3376 CLEAR_PENDING_EXCEPTION;
3380 // Start up the WatcherThread if there are any periodic tasks
3381 // NOTE: All PeriodicTasks should be registered by now. If they
3382 // aren't, late joiners might appear to start slowly (we might
3383 // take a while to process their first tick).
3384 if (PeriodicTask::num_tasks() > 0) {
3385 WatcherThread::start();
3388 // Give os specific code one last chance to start
3391 create_vm_timer.end();
3395 // type for the Agent_OnLoad and JVM_OnLoad entry points
3397 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3399 // Find a command line agent library and return its entry point for
3400 // -agentlib: -agentpath: -Xrun
3401 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3402 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3403 OnLoadEntry_t on_load_entry = NULL;
3404 void *library = agent->os_lib(); // check if we have looked it up before
3406 if (library == NULL) {
3407 char buffer[JVM_MAXPATHLEN];
3409 const char *name = agent->name();
3410 const char *msg = "Could not find agent library ";
3412 if (agent->is_absolute_path()) {
3413 library = os::dll_load(name, ebuf, sizeof ebuf);
3414 if (library == NULL) {
3415 const char *sub_msg = " in absolute path, with error: ";
3416 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3417 char *buf = NEW_C_HEAP_ARRAY(char, len);
3418 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3419 // If we can't find the agent, exit.
3420 vm_exit_during_initialization(buf, NULL);
3421 FREE_C_HEAP_ARRAY(char, buf);
3424 // Try to load the agent from the standard dll directory
3425 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3426 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3428 // Download instrument dll
3429 if (library == NULL && strcmp(name, "instrument") == 0) {
3430 char *props = Arguments::get_kernel_properties();
3431 char *home = Arguments::get_java_home();
3432 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3433 " sun.jkernel.DownloadManager -download client_jvm";
3434 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3435 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3436 jio_snprintf(cmd, length, fmt, home, props);
3437 int status = os::fork_and_exec(cmd);
3441 vm_exit_during_initialization("fork_and_exec failed: %s",
3444 FREE_C_HEAP_ARRAY(char, cmd);
3445 // when this comes back the instrument.dll should be where it belongs.
3446 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3449 if (library == NULL) { // Try the local directory
3451 os::dll_build_name(buffer, sizeof(buffer), ns, name);
3452 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3453 if (library == NULL) {
3454 const char *sub_msg = " on the library path, with error: ";
3455 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3456 char *buf = NEW_C_HEAP_ARRAY(char, len);
3457 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3458 // If we can't find the agent, exit.
3459 vm_exit_during_initialization(buf, NULL);
3460 FREE_C_HEAP_ARRAY(char, buf);
3464 agent->set_os_lib(library);
3467 // Find the OnLoad function.
3468 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3469 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index]));
3470 if (on_load_entry != NULL) break;
3472 return on_load_entry;
3475 // Find the JVM_OnLoad entry point
3476 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3477 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3478 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3481 // Find the Agent_OnLoad entry point
3482 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3483 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3484 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3487 // For backwards compatibility with -Xrun
3488 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3489 // treated like -agentpath:
3490 // Must be called before agent libraries are created
3491 void Threads::convert_vm_init_libraries_to_agents() {
3492 AgentLibrary* agent;
3495 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3496 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3497 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3499 // If there is an JVM_OnLoad function it will get called later,
3500 // otherwise see if there is an Agent_OnLoad
3501 if (on_load_entry == NULL) {
3502 on_load_entry = lookup_agent_on_load(agent);
3503 if (on_load_entry != NULL) {
3504 // switch it to the agent list -- so that Agent_OnLoad will be called,
3505 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3506 Arguments::convert_library_to_agent(agent);
3508 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3514 // Create agents for -agentlib: -agentpath: and converted -Xrun
3515 // Invokes Agent_OnLoad
3516 // Called very early -- before JavaThreads exist
3517 void Threads::create_vm_init_agents() {
3518 extern struct JavaVM_ main_vm;
3519 AgentLibrary* agent;
3521 JvmtiExport::enter_onload_phase();
3522 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3523 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3525 if (on_load_entry != NULL) {
3526 // Invoke the Agent_OnLoad function
3527 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3528 if (err != JNI_OK) {
3529 vm_exit_during_initialization("agent library failed to init", agent->name());
3532 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3535 JvmtiExport::enter_primordial_phase();
3539 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3542 void Threads::shutdown_vm_agents() {
3543 // Send any Agent_OnUnload notifications
3544 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3545 extern struct JavaVM_ main_vm;
3546 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3548 // Find the Agent_OnUnload function.
3549 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3550 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3551 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3553 // Invoke the Agent_OnUnload function
3554 if (unload_entry != NULL) {
3555 JavaThread* thread = JavaThread::current();
3556 ThreadToNativeFromVM ttn(thread);
3557 HandleMark hm(thread);
3558 (*unload_entry)(&main_vm);
3565 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3566 // Invokes JVM_OnLoad
3567 void Threads::create_vm_init_libraries() {
3568 extern struct JavaVM_ main_vm;
3569 AgentLibrary* agent;
3571 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3572 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3574 if (on_load_entry != NULL) {
3575 // Invoke the JVM_OnLoad function
3576 JavaThread* thread = JavaThread::current();
3577 ThreadToNativeFromVM ttn(thread);
3578 HandleMark hm(thread);
3579 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3580 if (err != JNI_OK) {
3581 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3584 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3589 // Last thread running calls java.lang.Shutdown.shutdown()
3590 void JavaThread::invoke_shutdown_hooks() {
3591 HandleMark hm(this);
3593 // We could get here with a pending exception, if so clear it now.
3594 if (this->has_pending_exception()) {
3595 this->clear_pending_exception();
3600 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3603 // SystemDictionary::resolve_or_null will return null if there was
3604 // an exception. If we cannot load the Shutdown class, just don't
3605 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3606 // and finalizers (if runFinalizersOnExit is set) won't be run.
3607 // Note that if a shutdown hook was registered or runFinalizersOnExit
3608 // was called, the Shutdown class would have already been loaded
3609 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3610 instanceKlassHandle shutdown_klass (THREAD, k);
3611 JavaValue result(T_VOID);
3612 JavaCalls::call_static(&result,
3614 vmSymbols::shutdown_method_name(),
3615 vmSymbols::void_method_signature(),
3618 CLEAR_PENDING_EXCEPTION;
3621 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3622 // the program falls off the end of main(). Another VM exit path is through
3623 // vm_exit() when the program calls System.exit() to return a value or when
3624 // there is a serious error in VM. The two shutdown paths are not exactly
3625 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3626 // and VM_Exit op at VM level.
3628 // Shutdown sequence:
3629 // + Wait until we are the last non-daemon thread to execute
3630 // <-- every thing is still working at this moment -->
3631 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3632 // shutdown hooks, run finalizers if finalization-on-exit
3633 // + Call before_exit(), prepare for VM exit
3634 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3635 // currently the only user of this mechanism is File.deleteOnExit())
3636 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3637 // post thread end and vm death events to JVMTI,
3638 // stop signal thread
3639 // + Call JavaThread::exit(), it will:
3640 // > release JNI handle blocks, remove stack guard pages
3641 // > remove this thread from Threads list
3642 // <-- no more Java code from this thread after this point -->
3643 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3644 // the compiler threads at safepoint
3645 // <-- do not use anything that could get blocked by Safepoint -->
3646 // + Disable tracing at JNI/JVM barriers
3647 // + Set _vm_exited flag for threads that are still running native code
3648 // + Delete this thread
3649 // + Call exit_globals()
3651 // > deletes PerfMemory resources
3652 // + Return to caller
3654 bool Threads::destroy_vm() {
3655 JavaThread* thread = JavaThread::current();
3657 // Wait until we are the last non-daemon thread to execute
3658 { MutexLocker nu(Threads_lock);
3659 while (Threads::number_of_non_daemon_threads() > 1 )
3660 // This wait should make safepoint checks, wait without a timeout,
3661 // and wait as a suspend-equivalent condition.
3663 // Note: If the FlatProfiler is running and this thread is waiting
3664 // for another non-daemon thread to finish, then the FlatProfiler
3665 // is waiting for the external suspend request on this thread to
3666 // complete. wait_for_ext_suspend_completion() will eventually
3667 // timeout, but that takes time. Making this wait a suspend-
3668 // equivalent condition solves that timeout problem.
3670 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3671 Mutex::_as_suspend_equivalent_flag);
3674 // Hang forever on exit if we are reporting an error.
3675 if (ShowMessageBoxOnError && is_error_reported()) {
3676 os::infinite_sleep();
3678 os::wait_for_keypress_at_exit();
3680 if (JDK_Version::is_jdk12x_version()) {
3681 // We are the last thread running, so check if finalizers should be run.
3682 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3683 HandleMark rm(thread);
3684 Universe::run_finalizers_on_exit();
3686 // run Java level shutdown hooks
3687 thread->invoke_shutdown_hooks();
3690 before_exit(thread);
3696 // 4945125 The vm thread comes to a safepoint during exit.
3697 // GC vm_operations can get caught at the safepoint, and the
3698 // heap is unparseable if they are caught. Grab the Heap_lock
3699 // to prevent this. The GC vm_operations will not be able to
3700 // queue until after the vm thread is dead.
3701 MutexLocker ml(Heap_lock);
3703 VMThread::wait_for_vm_thread_exit();
3704 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3705 VMThread::destroy();
3708 // clean up ideal graph printers
3709 #if defined(COMPILER2) && !defined(PRODUCT)
3710 IdealGraphPrinter::clean_up();
3713 // Now, all Java threads are gone except daemon threads. Daemon threads
3714 // running Java code or in VM are stopped by the Safepoint. However,
3715 // daemon threads executing native code are still running. But they
3716 // will be stopped at native=>Java/VM barriers. Note that we can't
3717 // simply kill or suspend them, as it is inherently deadlock-prone.
3720 // disable function tracing at JNI/JVM barriers
3721 TraceJNICalls = false;
3722 TraceJVMCalls = false;
3723 TraceRuntimeCalls = false;
3726 VM_Exit::set_vm_exited();
3728 notify_vm_shutdown();
3732 // exit_globals() will delete tty
3739 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3740 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3741 return is_supported_jni_version(version);
3745 jboolean Threads::is_supported_jni_version(jint version) {
3746 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3747 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3748 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3753 void Threads::add(JavaThread* p, bool force_daemon) {
3754 // The threads lock must be owned at this point
3755 assert_locked_or_safepoint(Threads_lock);
3757 // See the comment for this method in thread.hpp for its purpose and
3758 // why it is called here.
3759 p->initialize_queues();
3760 p->set_next(_thread_list);
3762 _number_of_threads++;
3763 oop threadObj = p->threadObj();
3765 // Bootstrapping problem: threadObj can be null for initial
3766 // JavaThread (or for threads attached via JNI)
3767 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3768 _number_of_non_daemon_threads++;
3772 ThreadService::add_thread(p, daemon);
3774 // Possible GC point.
3775 Events::log("Thread added: " INTPTR_FORMAT, p);
3778 void Threads::remove(JavaThread* p) {
3779 // Extra scope needed for Thread_lock, so we can check
3780 // that we do not remove thread without safepoint code notice
3781 { MutexLocker ml(Threads_lock);
3783 assert(includes(p), "p must be present");
3785 JavaThread* current = _thread_list;
3786 JavaThread* prev = NULL;
3788 while (current != p) {
3790 current = current->next();
3794 prev->set_next(current->next());
3796 _thread_list = p->next();
3798 _number_of_threads--;
3799 oop threadObj = p->threadObj();
3801 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3802 _number_of_non_daemon_threads--;
3805 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3806 // on destroy_vm will wake up.
3807 if (number_of_non_daemon_threads() == 1)
3808 Threads_lock->notify_all();
3810 ThreadService::remove_thread(p, daemon);
3812 // Make sure that safepoint code disregard this thread. This is needed since
3813 // the thread might mess around with locks after this point. This can cause it
3814 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3815 // of this thread since it is removed from the queue.
3816 p->set_terminated_value();
3817 } // unlock Threads_lock
3819 // Since Events::log uses a lock, we grab it outside the Threads_lock
3820 Events::log("Thread exited: " INTPTR_FORMAT, p);
3823 // Threads_lock must be held when this is called (or must be called during a safepoint)
3824 bool Threads::includes(JavaThread* p) {
3825 assert(Threads_lock->is_locked(), "sanity check");
3826 ALL_JAVA_THREADS(q) {
3834 // Operations on the Threads list for GC. These are not explicitly locked,
3835 // but the garbage collector must provide a safe context for them to run.
3836 // In particular, these things should never be called when the Threads_lock
3837 // is held by some other thread. (Note: the Safepoint abstraction also
3838 // uses the Threads_lock to gurantee this property. It also makes sure that
3839 // all threads gets blocked when exiting or starting).
3841 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3842 ALL_JAVA_THREADS(p) {
3845 VMThread::vm_thread()->oops_do(f, cf);
3848 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3849 // Introduce a mechanism allowing parallel threads to claim threads as
3850 // root groups. Overhead should be small enough to use all the time,
3851 // even in sequential code.
3852 SharedHeap* sh = SharedHeap::heap();
3853 bool is_par = (sh->n_par_threads() > 0);
3854 int cp = SharedHeap::heap()->strong_roots_parity();
3855 ALL_JAVA_THREADS(p) {
3856 if (p->claim_oops_do(is_par, cp)) {
3860 VMThread* vmt = VMThread::vm_thread();
3861 if (vmt->claim_oops_do(is_par, cp))
3862 vmt->oops_do(f, cf);
3866 // Used by ParallelScavenge
3867 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3868 ALL_JAVA_THREADS(p) {
3869 q->enqueue(new ThreadRootsTask(p));
3871 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3874 // Used by Parallel Old
3875 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3876 ALL_JAVA_THREADS(p) {
3877 q->enqueue(new ThreadRootsMarkingTask(p));
3879 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3883 void Threads::nmethods_do(CodeBlobClosure* cf) {
3884 ALL_JAVA_THREADS(p) {
3887 VMThread::vm_thread()->nmethods_do(cf);
3890 void Threads::gc_epilogue() {
3891 ALL_JAVA_THREADS(p) {
3896 void Threads::gc_prologue() {
3897 ALL_JAVA_THREADS(p) {
3902 void Threads::deoptimized_wrt_marked_nmethods() {
3903 ALL_JAVA_THREADS(p) {
3904 p->deoptimized_wrt_marked_nmethods();
3909 // Get count Java threads that are waiting to enter the specified monitor.
3910 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3911 address monitor, bool doLock) {
3912 assert(doLock || SafepointSynchronize::is_at_safepoint(),
3913 "must grab Threads_lock or be at safepoint");
3914 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3918 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3919 ALL_JAVA_THREADS(p) {
3920 if (p->is_Compiler_thread()) continue;
3922 address pending = (address)p->current_pending_monitor();
3923 if (pending == monitor) { // found a match
3924 if (i < count) result->append(p); // save the first count matches
3933 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3935 Threads_lock->owned_by_self() ||
3936 SafepointSynchronize::is_at_safepoint(),
3937 "must grab Threads_lock or be at safepoint");
3939 // NULL owner means not locked so we can skip the search
3940 if (owner == NULL) return NULL;
3943 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3944 ALL_JAVA_THREADS(p) {
3945 // first, see if owner is the address of a Java thread
3946 if (owner == (address)p) return p;
3949 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3950 if (UseHeavyMonitors) return NULL;
3953 // If we didn't find a matching Java thread and we didn't force use of
3954 // heavyweight monitors, then the owner is the stack address of the
3955 // Lock Word in the owning Java thread's stack.
3957 JavaThread* the_owner = NULL;
3959 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3960 ALL_JAVA_THREADS(q) {
3961 if (q->is_lock_owned(owner)) {
3967 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3971 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3972 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3974 st->print_cr(os::local_time_string(buf, sizeof(buf)));
3976 st->print_cr("Full thread dump %s (%s %s):",
3977 Abstract_VM_Version::vm_name(),
3978 Abstract_VM_Version::vm_release(),
3979 Abstract_VM_Version::vm_info_string()
3984 // Dump concurrent locks
3985 ConcurrentLocksDump concurrent_locks;
3986 if (print_concurrent_locks) {
3987 concurrent_locks.dump_at_safepoint();
3991 ALL_JAVA_THREADS(p) {
3995 if (internal_format) {
3998 p->print_stack_on(st);
4003 if (print_concurrent_locks) {
4004 concurrent_locks.print_locks_on(p, st);
4009 VMThread::vm_thread()->print_on(st);
4011 Universe::heap()->print_gc_threads_on(st);
4012 WatcherThread* wt = WatcherThread::watcher_thread();
4013 if (wt != NULL) wt->print_on(st);
4015 CompileBroker::print_compiler_threads_on(st);
4019 // Threads::print_on_error() is called by fatal error handler. It's possible
4020 // that VM is not at safepoint and/or current thread is inside signal handler.
4021 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4022 // memory (even in resource area), it might deadlock the error handler.
4023 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4024 bool found_current = false;
4025 st->print_cr("Java Threads: ( => current thread )");
4026 ALL_JAVA_THREADS(thread) {
4027 bool is_current = (current == thread);
4028 found_current = found_current || is_current;
4030 st->print("%s", is_current ? "=>" : " ");
4032 st->print(PTR_FORMAT, thread);
4034 thread->print_on_error(st, buf, buflen);
4039 st->print_cr("Other Threads:");
4040 if (VMThread::vm_thread()) {
4041 bool is_current = (current == VMThread::vm_thread());
4042 found_current = found_current || is_current;
4043 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4045 st->print(PTR_FORMAT, VMThread::vm_thread());
4047 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4050 WatcherThread* wt = WatcherThread::watcher_thread();
4052 bool is_current = (current == wt);
4053 found_current = found_current || is_current;
4054 st->print("%s", is_current ? "=>" : " ");
4056 st->print(PTR_FORMAT, wt);
4058 wt->print_on_error(st, buf, buflen);
4061 if (!found_current) {
4063 st->print("=>" PTR_FORMAT " (exited) ", current);
4064 current->print_on_error(st, buf, buflen);
4069 // Internal SpinLock and Mutex
4070 // Based on ParkEvent
4072 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4074 // We employ SpinLocks _only for low-contention, fixed-length
4075 // short-duration critical sections where we're concerned
4076 // about native mutex_t or HotSpot Mutex:: latency.
4077 // The mux construct provides a spin-then-block mutual exclusion
4080 // Testing has shown that contention on the ListLock guarding gFreeList
4081 // is common. If we implement ListLock as a simple SpinLock it's common
4082 // for the JVM to devolve to yielding with little progress. This is true
4083 // despite the fact that the critical sections protected by ListLock are
4086 // TODO-FIXME: ListLock should be of type SpinLock.
4087 // We should make this a 1st-class type, integrated into the lock
4088 // hierarchy as leaf-locks. Critically, the SpinLock structure
4089 // should have sufficient padding to avoid false-sharing and excessive
4090 // cache-coherency traffic.
4093 typedef volatile int SpinLockT ;
4095 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4096 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4097 return ; // normal fast-path return
4100 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4101 TEVENT (SpinAcquire - ctx) ;
4107 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4109 // Consider using a simple NakedSleep() instead.
4110 // Then SpinAcquire could be called by non-JVM threads
4111 Thread::current()->_ParkEvent->park(1) ;
4120 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4124 void Thread::SpinRelease (volatile int * adr) {
4125 assert (*adr != 0, "invariant") ;
4126 OrderAccess::fence() ; // guarantee at least release consistency.
4127 // Roach-motel semantics.
4128 // It's safe if subsequent LDs and STs float "up" into the critical section,
4129 // but prior LDs and STs within the critical section can't be allowed
4130 // to reorder or float past the ST that releases the lock.
4134 // muxAcquire and muxRelease:
4136 // * muxAcquire and muxRelease support a single-word lock-word construct.
4137 // The LSB of the word is set IFF the lock is held.
4138 // The remainder of the word points to the head of a singly-linked list
4139 // of threads blocked on the lock.
4141 // * The current implementation of muxAcquire-muxRelease uses its own
4142 // dedicated Thread._MuxEvent instance. If we're interested in
4143 // minimizing the peak number of extant ParkEvent instances then
4144 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4145 // as certain invariants were satisfied. Specifically, care would need
4146 // to be taken with regards to consuming unpark() "permits".
4147 // A safe rule of thumb is that a thread would never call muxAcquire()
4148 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4149 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4150 // consume an unpark() permit intended for monitorenter, for instance.
4151 // One way around this would be to widen the restricted-range semaphore
4152 // implemented in park(). Another alternative would be to provide
4153 // multiple instances of the PlatformEvent() for each thread. One
4154 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4157 // -- Only as leaf locks
4158 // -- for short-term locking only as muxAcquire does not perform
4159 // thread state transitions.
4162 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4163 // but with parking or spin-then-park instead of pure spinning.
4164 // * Use Taura-Oyama-Yonenzawa locks.
4165 // * It's possible to construct a 1-0 lock if we encode the lockword as
4166 // (List,LockByte). Acquire will CAS the full lockword while Release
4167 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4168 // acquiring threads use timers (ParkTimed) to detect and recover from
4169 // the stranding window. Thread/Node structures must be aligned on 256-byte
4170 // boundaries by using placement-new.
4171 // * Augment MCS with advisory back-link fields maintained with CAS().
4172 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4173 // The validity of the backlinks must be ratified before we trust the value.
4174 // If the backlinks are invalid the exiting thread must back-track through the
4175 // the forward links, which are always trustworthy.
4176 // * Add a successor indication. The LockWord is currently encoded as
4177 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4178 // to provide the usual futile-wakeup optimization.
4179 // See RTStt for details.
4180 // * Consider schedctl.sc_nopreempt to cover the critical section.
4184 typedef volatile intptr_t MutexT ; // Mux Lock-word
4185 enum MuxBits { LOCKBIT = 1 } ;
4187 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4188 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4189 if (w == 0) return ;
4190 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4194 TEVENT (muxAcquire - Contention) ;
4195 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4196 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4198 int its = (os::is_MP() ? 100 : 0) + 1 ;
4200 // Optional spin phase: spin-then-park strategy
4201 while (--its >= 0) {
4203 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4209 Self->OnList = intptr_t(Lock) ;
4210 // The following fence() isn't _strictly necessary as the subsequent
4211 // CAS() both serializes execution and ratifies the fetched *Lock value.
4212 OrderAccess::fence();
4215 if ((w & LOCKBIT) == 0) {
4216 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4217 Self->OnList = 0 ; // hygiene - allows stronger asserts
4220 continue ; // Interference -- *Lock changed -- Just retry
4222 assert (w & LOCKBIT, "invariant") ;
4223 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4224 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4227 while (Self->OnList != 0) {
4233 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4234 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4235 if (w == 0) return ;
4236 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4240 TEVENT (muxAcquire - Contention) ;
4241 ParkEvent * ReleaseAfter = NULL ;
4243 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4245 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4247 guarantee (ev->OnList == 0, "invariant") ;
4248 int its = (os::is_MP() ? 100 : 0) + 1 ;
4250 // Optional spin phase: spin-then-park strategy
4251 while (--its >= 0) {
4253 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4254 if (ReleaseAfter != NULL) {
4255 ParkEvent::Release (ReleaseAfter) ;
4262 ev->OnList = intptr_t(Lock) ;
4263 // The following fence() isn't _strictly necessary as the subsequent
4264 // CAS() both serializes execution and ratifies the fetched *Lock value.
4265 OrderAccess::fence();
4268 if ((w & LOCKBIT) == 0) {
4269 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4271 // We call ::Release while holding the outer lock, thus
4272 // artificially lengthening the critical section.
4273 // Consider deferring the ::Release() until the subsequent unlock(),
4274 // after we've dropped the outer lock.
4275 if (ReleaseAfter != NULL) {
4276 ParkEvent::Release (ReleaseAfter) ;
4280 continue ; // Interference -- *Lock changed -- Just retry
4282 assert (w & LOCKBIT, "invariant") ;
4283 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4284 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4287 while (ev->OnList != 0) {
4293 // Release() must extract a successor from the list and then wake that thread.
4294 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4295 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4296 // Release() would :
4297 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4298 // (B) Extract a successor from the private list "in-hand"
4299 // (C) attempt to CAS() the residual back into *Lock over null.
4300 // If there were any newly arrived threads and the CAS() would fail.
4301 // In that case Release() would detach the RATs, re-merge the list in-hand
4302 // with the RATs and repeat as needed. Alternately, Release() might
4303 // detach and extract a successor, but then pass the residual list to the wakee.
4304 // The wakee would be responsible for reattaching and remerging before it
4305 // competed for the lock.
4307 // Both "pop" and DMR are immune from ABA corruption -- there can be
4308 // multiple concurrent pushers, but only one popper or detacher.
4309 // This implementation pops from the head of the list. This is unfair,
4310 // but tends to provide excellent throughput as hot threads remain hot.
4311 // (We wake recently run threads first).
4313 void Thread::muxRelease (volatile intptr_t * Lock) {
4315 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4316 assert (w & LOCKBIT, "invariant") ;
4317 if (w == LOCKBIT) return ;
4318 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4319 assert (List != NULL, "invariant") ;
4320 assert (List->OnList == intptr_t(Lock), "invariant") ;
4321 ParkEvent * nxt = List->ListNext ;
4323 // The following CAS() releases the lock and pops the head element.
4324 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4328 OrderAccess::fence() ;
4335 void Threads::verify() {
4336 ALL_JAVA_THREADS(p) {
4339 VMThread* thread = VMThread::vm_thread();
4340 if (thread != NULL) thread->verify();