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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 "memory/oopFactory.hpp"
35 #include "memory/universe.inline.hpp"
36 #include "oops/instanceKlass.hpp"
37 #include "oops/objArrayOop.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "oops/symbolOop.hpp"
40 #include "prims/jvm_misc.hpp"
41 #include "prims/jvmtiExport.hpp"
42 #include "prims/jvmtiThreadState.hpp"
43 #include "prims/privilegedStack.hpp"
44 #include "runtime/aprofiler.hpp"
45 #include "runtime/arguments.hpp"
46 #include "runtime/biasedLocking.hpp"
47 #include "runtime/deoptimization.hpp"
48 #include "runtime/fprofiler.hpp"
49 #include "runtime/frame.inline.hpp"
50 #include "runtime/hpi.hpp"
51 #include "runtime/init.hpp"
52 #include "runtime/interfaceSupport.hpp"
53 #include "runtime/java.hpp"
54 #include "runtime/javaCalls.hpp"
55 #include "runtime/jniPeriodicChecker.hpp"
56 #include "runtime/memprofiler.hpp"
57 #include "runtime/mutexLocker.hpp"
58 #include "runtime/objectMonitor.hpp"
59 #include "runtime/osThread.hpp"
60 #include "runtime/safepoint.hpp"
61 #include "runtime/sharedRuntime.hpp"
62 #include "runtime/statSampler.hpp"
63 #include "runtime/stubRoutines.hpp"
64 #include "runtime/task.hpp"
65 #include "runtime/threadCritical.hpp"
66 #include "runtime/threadLocalStorage.hpp"
67 #include "runtime/vframe.hpp"
68 #include "runtime/vframeArray.hpp"
69 #include "runtime/vframe_hp.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "runtime/vm_operations.hpp"
72 #include "services/attachListener.hpp"
73 #include "services/management.hpp"
74 #include "services/threadService.hpp"
75 #include "utilities/defaultStream.hpp"
76 #include "utilities/dtrace.hpp"
77 #include "utilities/events.hpp"
78 #include "utilities/preserveException.hpp"
79 #ifdef TARGET_OS_FAMILY_linux
80 # include "os_linux.inline.hpp"
81 # include "thread_linux.inline.hpp"
83 #ifdef TARGET_OS_FAMILY_solaris
84 # include "os_solaris.inline.hpp"
85 # include "thread_solaris.inline.hpp"
87 #ifdef TARGET_OS_FAMILY_windows
88 # include "os_windows.inline.hpp"
89 # include "thread_windows.inline.hpp"
92 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
93 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
94 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
97 #include "c1/c1_Compiler.hpp"
100 #include "opto/c2compiler.hpp"
101 #include "opto/idealGraphPrinter.hpp"
104 #ifdef DTRACE_ENABLED
106 // Only bother with this argument setup if dtrace is available
108 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);
109 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);
110 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,
111 intptr_t, intptr_t, bool);
112 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,
113 intptr_t, intptr_t, bool);
115 #define DTRACE_THREAD_PROBE(probe, javathread) \
117 ResourceMark rm(this); \
119 const char* name = (javathread)->get_thread_name(); \
120 len = strlen(name); \
121 HS_DTRACE_PROBE5(hotspot, thread__##probe, \
123 java_lang_Thread::thread_id((javathread)->threadObj()), \
124 (javathread)->osthread()->thread_id(), \
125 java_lang_Thread::is_daemon((javathread)->threadObj())); \
128 #else // ndef DTRACE_ENABLED
130 #define DTRACE_THREAD_PROBE(probe, javathread)
132 #endif // ndef DTRACE_ENABLED
138 // - ConcurrentMarkSweepThread
142 // ======= Thread ========
144 // Support for forcing alignment of thread objects for biased locking
145 void* Thread::operator new(size_t size) {
146 if (UseBiasedLocking) {
147 const int alignment = markOopDesc::biased_lock_alignment;
148 size_t aligned_size = size + (alignment - sizeof(intptr_t));
149 void* real_malloc_addr = CHeapObj::operator new(aligned_size);
150 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
151 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
152 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
153 "JavaThread alignment code overflowed allocated storage");
154 if (TraceBiasedLocking) {
155 if (aligned_addr != real_malloc_addr)
156 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
157 real_malloc_addr, aligned_addr);
159 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
162 return CHeapObj::operator new(size);
166 void Thread::operator delete(void* p) {
167 if (UseBiasedLocking) {
168 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
169 CHeapObj::operator delete(real_malloc_addr);
171 CHeapObj::operator delete(p);
176 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
188 // allocated data structures
189 set_resource_area(new ResourceArea());
190 set_handle_area(new HandleArea(NULL));
191 set_active_handles(NULL);
192 set_free_handle_block(NULL);
193 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 _vm_operation_started_count = 0;
210 _vm_operation_completed_count = 0;
211 _current_pending_monitor = NULL;
212 _current_pending_monitor_is_from_java = true;
213 _current_waiting_monitor = NULL;
214 _num_nested_signal = 0;
217 omFreeProvision = 32 ;
221 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);
224 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
225 _hashStateX = os::random() ;
226 _hashStateY = 842502087 ;
227 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ;
228 _hashStateW = 273326509 ;
235 // Many of the following fields are effectively final - immutable
236 // Note that nascent threads can't use the Native Monitor-Mutex
237 // construct until the _MutexEvent is initialized ...
238 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
239 // we might instead use a stack of ParkEvents that we could provision on-demand.
240 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
242 _ParkEvent = ParkEvent::Allocate (this) ;
243 _SleepEvent = ParkEvent::Allocate (this) ;
244 _MutexEvent = ParkEvent::Allocate (this) ;
245 _MuxEvent = ParkEvent::Allocate (this) ;
247 #ifdef CHECK_UNHANDLED_OOPS
248 if (CheckUnhandledOops) {
249 _unhandled_oops = new UnhandledOops(this);
251 #endif // CHECK_UNHANDLED_OOPS
253 if (UseBiasedLocking) {
254 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
255 assert(this == _real_malloc_address ||
256 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
257 "bug in forced alignment of thread objects");
262 void Thread::initialize_thread_local_storage() {
263 // Note: Make sure this method only calls
264 // non-blocking operations. Otherwise, it might not work
265 // with the thread-startup/safepoint interaction.
267 // During Java thread startup, safepoint code should allow this
268 // method to complete because it may need to allocate memory to
269 // store information for the new thread.
271 // initialize structure dependent on thread local storage
272 ThreadLocalStorage::set_thread(this);
274 // set up any platform-specific state.
275 os::initialize_thread();
279 void Thread::record_stack_base_and_size() {
280 set_stack_base(os::current_stack_base());
281 set_stack_size(os::current_stack_size());
286 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
287 ObjectSynchronizer::omFlush (this) ;
289 // deallocate data structures
290 delete resource_area();
291 // since the handle marks are using the handle area, we have to deallocated the root
292 // handle mark before deallocating the thread's handle area,
293 assert(last_handle_mark() != NULL, "check we have an element");
294 delete last_handle_mark();
295 assert(last_handle_mark() == NULL, "check we have reached the end");
297 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
298 // We NULL out the fields for good hygiene.
299 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ;
300 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ;
301 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ;
302 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ;
304 delete handle_area();
306 // osthread() can be NULL, if creation of thread failed.
307 if (osthread() != NULL) os::free_thread(osthread());
311 // clear thread local storage if the Thread is deleting itself
312 if (this == Thread::current()) {
313 ThreadLocalStorage::set_thread(NULL);
315 // In the case where we're not the current thread, invalidate all the
316 // caches in case some code tries to get the current thread or the
317 // thread that was destroyed, and gets stale information.
318 ThreadLocalStorage::invalidate_all();
320 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
323 // NOTE: dummy function for assertion purpose.
325 ShouldNotReachHere();
329 // Private method to check for dangling thread pointer
330 void check_for_dangling_thread_pointer(Thread *thread) {
331 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
332 "possibility of dangling Thread pointer");
338 // Tracing method for basic thread operations
339 void Thread::trace(const char* msg, const Thread* const thread) {
340 if (!TraceThreadEvents) return;
343 const char *name = "non-Java thread";
345 if (thread->is_Java_thread()
346 && !thread->is_Compiler_thread()) {
347 // The Threads_lock must be held to get information about
348 // this thread but may not be in some situations when
349 // tracing thread events.
350 bool release_Threads_lock = false;
351 if (!Threads_lock->owned_by_self()) {
352 Threads_lock->lock();
353 release_Threads_lock = true;
355 JavaThread* jt = (JavaThread *)thread;
356 name = (char *)jt->get_thread_name();
357 oop thread_oop = jt->threadObj();
358 if (thread_oop != NULL) {
359 prio = java_lang_Thread::priority(thread_oop);
361 if (release_Threads_lock) {
362 Threads_lock->unlock();
365 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);
370 ThreadPriority Thread::get_priority(const Thread* const thread) {
371 trace("get priority", thread);
372 ThreadPriority priority;
373 // Can return an error!
374 (void)os::get_priority(thread, priority);
375 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
379 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
380 trace("set priority", thread);
381 debug_only(check_for_dangling_thread_pointer(thread);)
382 // Can return an error!
383 (void)os::set_priority(thread, priority);
387 void Thread::start(Thread* thread) {
388 trace("start", thread);
389 // Start is different from resume in that its safety is guaranteed by context or
390 // being called from a Java method synchronized on the Thread object.
391 if (!DisableStartThread) {
392 if (thread->is_Java_thread()) {
393 // Initialize the thread state to RUNNABLE before starting this thread.
394 // Can not set it after the thread started because we do not know the
395 // exact thread state at that time. It could be in MONITOR_WAIT or
396 // in SLEEPING or some other state.
397 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
398 java_lang_Thread::RUNNABLE);
400 os::start_thread(thread);
404 // Enqueue a VM_Operation to do the job for us - sometime later
405 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
406 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
407 VMThread::execute(vm_stop);
412 // Check if an external suspend request has completed (or has been
413 // cancelled). Returns true if the thread is externally suspended and
416 // The bits parameter returns information about the code path through
417 // the routine. Useful for debugging:
419 // set in is_ext_suspend_completed():
420 // 0x00000001 - routine was entered
421 // 0x00000010 - routine return false at end
422 // 0x00000100 - thread exited (return false)
423 // 0x00000200 - suspend request cancelled (return false)
424 // 0x00000400 - thread suspended (return true)
425 // 0x00001000 - thread is in a suspend equivalent state (return true)
426 // 0x00002000 - thread is native and walkable (return true)
427 // 0x00004000 - thread is native_trans and walkable (needed retry)
429 // set in wait_for_ext_suspend_completion():
430 // 0x00010000 - routine was entered
431 // 0x00020000 - suspend request cancelled before loop (return false)
432 // 0x00040000 - thread suspended before loop (return true)
433 // 0x00080000 - suspend request cancelled in loop (return false)
434 // 0x00100000 - thread suspended in loop (return true)
435 // 0x00200000 - suspend not completed during retry loop (return false)
438 // Helper class for tracing suspend wait debug bits.
440 // 0x00000100 indicates that the target thread exited before it could
441 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
442 // 0x00080000 each indicate a cancelled suspend request so they don't
443 // count as wait failures either.
444 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
446 class TraceSuspendDebugBits : public StackObj {
450 bool called_by_wait; // meaningful when !is_wait
454 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
458 called_by_wait = _called_by_wait;
462 ~TraceSuspendDebugBits() {
465 // By default, don't trace bits for is_ext_suspend_completed() calls.
466 // That trace is very chatty.
469 if (!called_by_wait) {
470 // If tracing for is_ext_suspend_completed() is enabled, then only
471 // trace calls to it from wait_for_ext_suspend_completion()
477 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
478 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
479 MutexLocker ml(Threads_lock); // needed for get_thread_name()
483 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
484 jt->get_thread_name(), *bits);
486 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
491 #undef DEBUG_FALSE_BITS
494 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {
495 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
497 bool did_trans_retry = false; // only do thread_in_native_trans retry once
498 bool do_trans_retry; // flag to force the retry
503 do_trans_retry = false;
506 // Thread is in the process of exiting. This is always checked
507 // first to reduce the risk of dereferencing a freed JavaThread.
512 if (!is_external_suspend()) {
513 // Suspend request is cancelled. This is always checked before
514 // is_ext_suspended() to reduce the risk of a rogue resume
515 // confusing the thread that made the suspend request.
520 if (is_ext_suspended()) {
521 // thread is suspended
526 // Now that we no longer do hard suspends of threads running
527 // native code, the target thread can be changing thread state
528 // while we are in this routine:
530 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
532 // We save a copy of the thread state as observed at this moment
533 // and make our decision about suspend completeness based on the
534 // copy. This closes the race where the thread state is seen as
535 // _thread_in_native_trans in the if-thread_blocked check, but is
536 // seen as _thread_blocked in if-thread_in_native_trans check.
537 JavaThreadState save_state = thread_state();
539 if (save_state == _thread_blocked && is_suspend_equivalent()) {
540 // If the thread's state is _thread_blocked and this blocking
541 // condition is known to be equivalent to a suspend, then we can
542 // consider the thread to be externally suspended. This means that
543 // the code that sets _thread_blocked has been modified to do
544 // self-suspension if the blocking condition releases. We also
545 // used to check for CONDVAR_WAIT here, but that is now covered by
546 // the _thread_blocked with self-suspension check.
548 // Return true since we wouldn't be here unless there was still an
549 // external suspend request.
552 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
553 // Threads running native code will self-suspend on native==>VM/Java
554 // transitions. If its stack is walkable (should always be the case
555 // unless this function is called before the actual java_suspend()
556 // call), then the wait is done.
559 } else if (!called_by_wait && !did_trans_retry &&
560 save_state == _thread_in_native_trans &&
561 frame_anchor()->walkable()) {
562 // The thread is transitioning from thread_in_native to another
563 // thread state. check_safepoint_and_suspend_for_native_trans()
564 // will force the thread to self-suspend. If it hasn't gotten
565 // there yet we may have caught the thread in-between the native
566 // code check above and the self-suspend. Lucky us. If we were
567 // called by wait_for_ext_suspend_completion(), then it
568 // will be doing the retries so we don't have to.
570 // Since we use the saved thread state in the if-statement above,
571 // there is a chance that the thread has already transitioned to
572 // _thread_blocked by the time we get here. In that case, we will
573 // make a single unnecessary pass through the logic below. This
574 // doesn't hurt anything since we still do the trans retry.
578 // Once the thread leaves thread_in_native_trans for another
579 // thread state, we break out of this retry loop. We shouldn't
580 // need this flag to prevent us from getting back here, but
581 // sometimes paranoia is good.
582 did_trans_retry = true;
584 // We wait for the thread to transition to a more usable state.
585 for (int i = 1; i <= SuspendRetryCount; i++) {
586 // We used to do an "os::yield_all(i)" call here with the intention
587 // that yielding would increase on each retry. However, the parameter
588 // is ignored on Linux which means the yield didn't scale up. Waiting
589 // on the SR_lock below provides a much more predictable scale up for
590 // the delay. It also provides a simple/direct point to check for any
591 // safepoint requests from the VMThread
593 // temporarily drops SR_lock while doing wait with safepoint check
594 // (if we're a JavaThread - the WatcherThread can also call this)
595 // and increase delay with each retry
596 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
598 // check the actual thread state instead of what we saved above
599 if (thread_state() != _thread_in_native_trans) {
600 // the thread has transitioned to another thread state so
601 // try all the checks (except this one) one more time.
602 do_trans_retry = true;
609 } while (do_trans_retry);
616 // Wait for an external suspend request to complete (or be cancelled).
617 // Returns true if the thread is externally suspended and false otherwise.
619 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
621 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
622 false /* !called_by_wait */, bits);
624 // local flag copies to minimize SR_lock hold time
629 // set a marker so is_ext_suspend_completed() knows we are the caller
632 // We use reset_bits to reinitialize the bits value at the top of
633 // each retry loop. This allows the caller to make use of any
634 // unused bits for their own marking purposes.
638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
639 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
641 pending = is_external_suspend();
643 // must release SR_lock to allow suspension to complete
646 // A cancelled suspend request is the only false return from
647 // is_ext_suspend_completed() that keeps us from entering the
658 for (int i = 1; i <= retries; i++) {
659 *bits = reset_bits; // reinit to only track last retry
661 // We used to do an "os::yield_all(i)" call here with the intention
662 // that yielding would increase on each retry. However, the parameter
663 // is ignored on Linux which means the yield didn't scale up. Waiting
664 // on the SR_lock below provides a much more predictable scale up for
665 // the delay. It also provides a simple/direct point to check for any
666 // safepoint requests from the VMThread
669 MutexLocker ml(SR_lock());
670 // wait with safepoint check (if we're a JavaThread - the WatcherThread
671 // can also call this) and increase delay with each retry
672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
674 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
677 // It is possible for the external suspend request to be cancelled
678 // (by a resume) before the actual suspend operation is completed.
679 // Refresh our local copy to see if we still need to wait.
680 pending = is_external_suspend();
684 // A cancelled suspend request is the only false return from
685 // is_ext_suspend_completed() that keeps us from staying in the
697 // thread did not suspend after all our retries
703 void JavaThread::record_jump(address target, address instr, const char* file, int line) {
705 // This should not need to be atomic as the only way for simultaneous
706 // updates is via interrupts. Even then this should be rare or non-existant
707 // and we don't care that much anyway.
709 int index = _jmp_ring_index;
710 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);
711 _jmp_ring[index]._target = (intptr_t) target;
712 _jmp_ring[index]._instruction = (intptr_t) instr;
713 _jmp_ring[index]._file = file;
714 _jmp_ring[index]._line = line;
718 // Called by flat profiler
719 // Callers have already called wait_for_ext_suspend_completion
720 // The assertion for that is currently too complex to put here:
721 bool JavaThread::profile_last_Java_frame(frame* _fr) {
722 bool gotframe = false;
723 // self suspension saves needed state.
724 if (has_last_Java_frame() && _anchor.walkable()) {
725 *_fr = pd_last_frame();
731 void Thread::interrupt(Thread* thread) {
732 trace("interrupt", thread);
733 debug_only(check_for_dangling_thread_pointer(thread);)
734 os::interrupt(thread);
737 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
738 trace("is_interrupted", thread);
739 debug_only(check_for_dangling_thread_pointer(thread);)
740 // Note: If clear_interrupted==false, this simply fetches and
741 // returns the value of the field osthread()->interrupted().
742 return os::is_interrupted(thread, clear_interrupted);
747 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
748 jint thread_parity = _oops_do_parity;
749 if (thread_parity != strong_roots_parity) {
750 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
751 if (res == thread_parity) return true;
753 guarantee(res == strong_roots_parity, "Or else what?");
754 assert(SharedHeap::heap()->n_par_threads() > 0,
755 "Should only fail when parallel.");
759 assert(SharedHeap::heap()->n_par_threads() > 0,
760 "Should only fail when parallel.");
764 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
765 active_handles()->oops_do(f);
766 // Do oop for ThreadShadow
767 f->do_oop((oop*)&_pending_exception);
768 handle_area()->oops_do(f);
771 void Thread::nmethods_do(CodeBlobClosure* cf) {
772 // no nmethods in a generic thread...
775 void Thread::print_on(outputStream* st) const {
776 // get_priority assumes osthread initialized
777 if (osthread() != NULL) {
778 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);
779 osthread()->print_on(st);
781 debug_only(if (WizardMode) print_owned_locks_on(st);)
784 // Thread::print_on_error() is called by fatal error handler. Don't use
785 // any lock or allocate memory.
786 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
787 if (is_VM_thread()) st->print("VMThread");
788 else if (is_Compiler_thread()) st->print("CompilerThread");
789 else if (is_Java_thread()) st->print("JavaThread");
790 else if (is_GC_task_thread()) st->print("GCTaskThread");
791 else if (is_Watcher_thread()) st->print("WatcherThread");
792 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
793 else st->print("Thread");
795 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
796 _stack_base - _stack_size, _stack_base);
799 st->print(" [id=%d]", osthread()->thread_id());
804 void Thread::print_owned_locks_on(outputStream* st) const {
805 Monitor *cur = _owned_locks;
807 st->print(" (no locks) ");
809 st->print_cr(" Locks owned:");
817 static int ref_use_count = 0;
819 bool Thread::owns_locks_but_compiled_lock() const {
820 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
821 if (cur != Compile_lock) return true;
831 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
832 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
833 // no threads which allow_vm_block's are held
834 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
835 // Check if current thread is allowed to block at a safepoint
836 if (!(_allow_safepoint_count == 0))
837 fatal("Possible safepoint reached by thread that does not allow it");
838 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
839 fatal("LEAF method calling lock?");
843 if (potential_vm_operation && is_Java_thread()
844 && !Universe::is_bootstrapping()) {
845 // Make sure we do not hold any locks that the VM thread also uses.
846 // This could potentially lead to deadlocks
847 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
848 // Threads_lock is special, since the safepoint synchronization will not start before this is
849 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
850 // since it is used to transfer control between JavaThreads and the VMThread
851 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!
852 if ( (cur->allow_vm_block() &&
853 cur != Threads_lock &&
854 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation
855 cur != VMOperationRequest_lock &&
856 cur != VMOperationQueue_lock) ||
857 cur->rank() == Mutex::special) {
858 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());
863 if (GCALotAtAllSafepoints) {
864 // We could enter a safepoint here and thus have a gc
865 InterfaceSupport::check_gc_alot();
871 bool Thread::is_in_stack(address adr) const {
872 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
873 address end = os::current_stack_pointer();
874 if (stack_base() >= adr && adr >= end) return true;
880 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
881 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
882 // used for compilation in the future. If that change is made, the need for these methods
883 // should be revisited, and they should be removed if possible.
885 bool Thread::is_lock_owned(address adr) const {
886 return on_local_stack(adr);
889 bool Thread::set_as_starting_thread() {
890 // NOTE: this must be called inside the main thread.
891 return os::create_main_thread((JavaThread*)this);
894 static void initialize_class(symbolHandle class_name, TRAPS) {
895 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
896 instanceKlass::cast(klass)->initialize(CHECK);
900 // Creates the initial ThreadGroup
901 static Handle create_initial_thread_group(TRAPS) {
902 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_ThreadGroup(), true, CHECK_NH);
903 instanceKlassHandle klass (THREAD, k);
905 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
907 JavaValue result(T_VOID);
908 JavaCalls::call_special(&result,
911 vmSymbolHandles::object_initializer_name(),
912 vmSymbolHandles::void_method_signature(),
915 Universe::set_system_thread_group(system_instance());
917 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
919 JavaValue result(T_VOID);
920 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
921 JavaCalls::call_special(&result,
924 vmSymbolHandles::object_initializer_name(),
925 vmSymbolHandles::threadgroup_string_void_signature(),
930 return main_instance;
933 // Creates the initial Thread
934 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {
935 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK_NULL);
936 instanceKlassHandle klass (THREAD, k);
937 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
939 java_lang_Thread::set_thread(thread_oop(), thread);
940 java_lang_Thread::set_priority(thread_oop(), NormPriority);
941 thread->set_threadObj(thread_oop());
943 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
945 JavaValue result(T_VOID);
946 JavaCalls::call_special(&result, thread_oop,
948 vmSymbolHandles::object_initializer_name(),
949 vmSymbolHandles::threadgroup_string_void_signature(),
956 static void call_initializeSystemClass(TRAPS) {
957 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
958 instanceKlassHandle klass (THREAD, k);
960 JavaValue result(T_VOID);
961 JavaCalls::call_static(&result, klass, vmSymbolHandles::initializeSystemClass_name(),
962 vmSymbolHandles::void_method_signature(), CHECK);
966 static void set_jkernel_boot_classloader_hook(TRAPS) {
967 klassOop k = SystemDictionary::sun_jkernel_DownloadManager_klass();
968 instanceKlassHandle klass (THREAD, k);
971 // sun.jkernel.DownloadManager may not present in the JDK; just return
975 JavaValue result(T_VOID);
976 JavaCalls::call_static(&result, klass, vmSymbolHandles::setBootClassLoaderHook_name(),
977 vmSymbolHandles::void_method_signature(), CHECK);
981 static void reset_vm_info_property(TRAPS) {
982 // the vm info string
983 ResourceMark rm(THREAD);
984 const char *vm_info = VM_Version::vm_info_string();
986 // java.lang.System class
987 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
988 instanceKlassHandle klass (THREAD, k);
990 // setProperty arguments
991 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
992 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
995 JavaValue r(T_OBJECT);
997 // public static String setProperty(String key, String value);
998 JavaCalls::call_static(&r,
1000 vmSymbolHandles::setProperty_name(),
1001 vmSymbolHandles::string_string_string_signature(),
1008 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {
1009 assert(thread_group.not_null(), "thread group should be specified");
1010 assert(threadObj() == NULL, "should only create Java thread object once");
1012 klassOop k = SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK);
1013 instanceKlassHandle klass (THREAD, k);
1014 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1016 java_lang_Thread::set_thread(thread_oop(), this);
1017 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1018 set_threadObj(thread_oop());
1020 JavaValue result(T_VOID);
1021 if (thread_name != NULL) {
1022 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1023 // Thread gets assigned specified name and null target
1024 JavaCalls::call_special(&result,
1027 vmSymbolHandles::object_initializer_name(),
1028 vmSymbolHandles::threadgroup_string_void_signature(),
1029 thread_group, // Argument 1
1033 // Thread gets assigned name "Thread-nnn" and null target
1034 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1035 JavaCalls::call_special(&result,
1038 vmSymbolHandles::object_initializer_name(),
1039 vmSymbolHandles::threadgroup_runnable_void_signature(),
1040 thread_group, // Argument 1
1041 Handle(), // Argument 2
1047 java_lang_Thread::set_daemon(thread_oop());
1050 if (HAS_PENDING_EXCEPTION) {
1054 KlassHandle group(this, SystemDictionary::ThreadGroup_klass());
1055 Handle threadObj(this, this->threadObj());
1057 JavaCalls::call_special(&result,
1060 vmSymbolHandles::add_method_name(),
1061 vmSymbolHandles::thread_void_signature(),
1068 // NamedThread -- non-JavaThread subclasses with multiple
1069 // uniquely named instances should derive from this.
1070 NamedThread::NamedThread() : Thread() {
1072 _processed_thread = NULL;
1075 NamedThread::~NamedThread() {
1076 if (_name != NULL) {
1077 FREE_C_HEAP_ARRAY(char, _name);
1082 void NamedThread::set_name(const char* format, ...) {
1083 guarantee(_name == NULL, "Only get to set name once.");
1084 _name = NEW_C_HEAP_ARRAY(char, max_name_len);
1085 guarantee(_name != NULL, "alloc failure");
1087 va_start(ap, format);
1088 jio_vsnprintf(_name, max_name_len, format, ap);
1092 // ======= WatcherThread ========
1094 // The watcher thread exists to simulate timer interrupts. It should
1095 // be replaced by an abstraction over whatever native support for
1096 // timer interrupts exists on the platform.
1098 WatcherThread* WatcherThread::_watcher_thread = NULL;
1099 volatile bool WatcherThread::_should_terminate = false;
1101 WatcherThread::WatcherThread() : Thread() {
1102 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1103 if (os::create_thread(this, os::watcher_thread)) {
1104 _watcher_thread = this;
1106 // Set the watcher thread to the highest OS priority which should not be
1107 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1108 // is created. The only normal thread using this priority is the reference
1109 // handler thread, which runs for very short intervals only.
1110 // If the VMThread's priority is not lower than the WatcherThread profiling
1111 // will be inaccurate.
1112 os::set_priority(this, MaxPriority);
1113 if (!DisableStartThread) {
1114 os::start_thread(this);
1119 void WatcherThread::run() {
1120 assert(this == watcher_thread(), "just checking");
1122 this->record_stack_base_and_size();
1123 this->initialize_thread_local_storage();
1124 this->set_active_handles(JNIHandleBlock::allocate_block());
1125 while(!_should_terminate) {
1126 assert(watcher_thread() == Thread::current(), "thread consistency check");
1127 assert(watcher_thread() == this, "thread consistency check");
1129 // Calculate how long it'll be until the next PeriodicTask work
1130 // should be done, and sleep that amount of time.
1131 size_t time_to_wait = PeriodicTask::time_to_wait();
1133 // we expect this to timeout - we only ever get unparked when
1134 // we should terminate
1136 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1138 jlong prev_time = os::javaTimeNanos();
1140 int res= _SleepEvent->park(time_to_wait);
1141 if (res == OS_TIMEOUT || _should_terminate)
1143 // spurious wakeup of some kind
1144 jlong now = os::javaTimeNanos();
1145 time_to_wait -= (now - prev_time) / 1000000;
1146 if (time_to_wait <= 0)
1152 if (is_error_reported()) {
1153 // A fatal error has happened, the error handler(VMError::report_and_die)
1154 // should abort JVM after creating an error log file. However in some
1155 // rare cases, the error handler itself might deadlock. Here we try to
1156 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1158 // This code is in WatcherThread because WatcherThread wakes up
1159 // periodically so the fatal error handler doesn't need to do anything;
1160 // also because the WatcherThread is less likely to crash than other
1164 if (!ShowMessageBoxOnError
1165 && (OnError == NULL || OnError[0] == '\0')
1166 && Arguments::abort_hook() == NULL) {
1167 os::sleep(this, 2 * 60 * 1000, false);
1168 fdStream err(defaultStream::output_fd());
1169 err.print_raw_cr("# [ timer expired, abort... ]");
1170 // skip atexit/vm_exit/vm_abort hooks
1174 // Wake up 5 seconds later, the fatal handler may reset OnError or
1175 // ShowMessageBoxOnError when it is ready to abort.
1176 os::sleep(this, 5 * 1000, false);
1180 PeriodicTask::real_time_tick(time_to_wait);
1182 // If we have no more tasks left due to dynamic disenrollment,
1183 // shut down the thread since we don't currently support dynamic enrollment
1184 if (PeriodicTask::num_tasks() == 0) {
1185 _should_terminate = true;
1189 // Signal that it is terminated
1191 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1192 _watcher_thread = NULL;
1193 Terminator_lock->notify();
1196 // Thread destructor usually does this..
1197 ThreadLocalStorage::set_thread(NULL);
1200 void WatcherThread::start() {
1201 if (watcher_thread() == NULL) {
1202 _should_terminate = false;
1203 // Create the single instance of WatcherThread
1204 new WatcherThread();
1208 void WatcherThread::stop() {
1209 // it is ok to take late safepoints here, if needed
1210 MutexLocker mu(Terminator_lock);
1211 _should_terminate = true;
1212 OrderAccess::fence(); // ensure WatcherThread sees update in main loop
1214 Thread* watcher = watcher_thread();
1215 if (watcher != NULL)
1216 watcher->_SleepEvent->unpark();
1218 while(watcher_thread() != NULL) {
1219 // This wait should make safepoint checks, wait without a timeout,
1220 // and wait as a suspend-equivalent condition.
1222 // Note: If the FlatProfiler is running, then this thread is waiting
1223 // for the WatcherThread to terminate and the WatcherThread, via the
1224 // FlatProfiler task, is waiting for the external suspend request on
1225 // this thread to complete. wait_for_ext_suspend_completion() will
1226 // eventually timeout, but that takes time. Making this wait a
1227 // suspend-equivalent condition solves that timeout problem.
1229 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1230 Mutex::_as_suspend_equivalent_flag);
1234 void WatcherThread::print_on(outputStream* st) const {
1235 st->print("\"%s\" ", name());
1236 Thread::print_on(st);
1240 // ======= JavaThread ========
1242 // A JavaThread is a normal Java thread
1244 void JavaThread::initialize() {
1245 // Initialize fields
1247 // Set the claimed par_id to -1 (ie not claiming any par_ids)
1248 set_claimed_par_id(-1);
1250 set_saved_exception_pc(NULL);
1251 set_threadObj(NULL);
1253 set_entry_point(NULL);
1254 set_jni_functions(jni_functions());
1255 set_callee_target(NULL);
1256 set_vm_result(NULL);
1257 set_vm_result_2(NULL);
1258 set_vframe_array_head(NULL);
1259 set_vframe_array_last(NULL);
1260 set_deferred_locals(NULL);
1261 set_deopt_mark(NULL);
1262 set_deopt_nmethod(NULL);
1263 clear_must_deopt_id();
1264 set_monitor_chunks(NULL);
1266 set_thread_state(_thread_new);
1267 _terminated = _not_terminated;
1268 _privileged_stack_top = NULL;
1269 _array_for_gc = NULL;
1270 _suspend_equivalent = false;
1271 _in_deopt_handler = 0;
1272 _doing_unsafe_access = false;
1273 _stack_guard_state = stack_guard_unused;
1274 _exception_oop = NULL;
1276 _exception_handler_pc = 0;
1277 _exception_stack_size = 0;
1278 _is_method_handle_return = 0;
1279 _jvmti_thread_state= NULL;
1280 _should_post_on_exceptions_flag = JNI_FALSE;
1281 _jvmti_get_loaded_classes_closure = NULL;
1282 _interp_only_mode = 0;
1283 _special_runtime_exit_condition = _no_async_condition;
1284 _pending_async_exception = NULL;
1285 _is_compiling = false;
1286 _thread_stat = NULL;
1287 _thread_stat = new ThreadStatistics();
1288 _blocked_on_compilation = false;
1289 _jni_active_critical = 0;
1290 _do_not_unlock_if_synchronized = false;
1291 _cached_monitor_info = NULL;
1292 _parker = Parker::Allocate(this) ;
1295 _jmp_ring_index = 0;
1296 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {
1297 record_jump(NULL, NULL, NULL, 0);
1299 #endif /* PRODUCT */
1301 set_thread_profiler(NULL);
1302 if (FlatProfiler::is_active()) {
1303 // This is where we would decide to either give each thread it's own profiler
1304 // or use one global one from FlatProfiler,
1305 // or up to some count of the number of profiled threads, etc.
1306 ThreadProfiler* pp = new ThreadProfiler();
1308 set_thread_profiler(pp);
1311 // Setup safepoint state info for this thread
1312 ThreadSafepointState::create(this);
1314 debug_only(_java_call_counter = 0);
1316 // JVMTI PopFrame support
1317 _popframe_condition = popframe_inactive;
1318 _popframe_preserved_args = NULL;
1319 _popframe_preserved_args_size = 0;
1325 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1326 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1329 JavaThread::JavaThread(bool is_attaching) :
1332 , _satb_mark_queue(&_satb_mark_queue_set),
1333 _dirty_card_queue(&_dirty_card_queue_set)
1337 _is_attaching = is_attaching;
1338 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");
1341 bool JavaThread::reguard_stack(address cur_sp) {
1342 if (_stack_guard_state != stack_guard_yellow_disabled) {
1343 return true; // Stack already guarded or guard pages not needed.
1346 if (register_stack_overflow()) {
1347 // For those architectures which have separate register and
1348 // memory stacks, we must check the register stack to see if
1349 // it has overflowed.
1353 // Java code never executes within the yellow zone: the latter is only
1354 // there to provoke an exception during stack banging. If java code
1355 // is executing there, either StackShadowPages should be larger, or
1356 // some exception code in c1, c2 or the interpreter isn't unwinding
1358 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1360 enable_stack_yellow_zone();
1364 bool JavaThread::reguard_stack(void) {
1365 return reguard_stack(os::current_stack_pointer());
1369 void JavaThread::block_if_vm_exited() {
1370 if (_terminated == _vm_exited) {
1371 // _vm_exited is set at safepoint, and Threads_lock is never released
1372 // we will block here forever
1373 Threads_lock->lock_without_safepoint_check();
1374 ShouldNotReachHere();
1379 // Remove this ifdef when C1 is ported to the compiler interface.
1380 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1382 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1385 , _satb_mark_queue(&_satb_mark_queue_set),
1386 _dirty_card_queue(&_dirty_card_queue_set)
1389 if (TraceThreadEvents) {
1390 tty->print_cr("creating thread %p", this);
1393 _is_attaching = false;
1394 set_entry_point(entry_point);
1395 // Create the native thread itself.
1397 os::ThreadType thr_type = os::java_thread;
1398 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1400 os::create_thread(this, thr_type, stack_sz);
1402 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1403 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1404 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1405 // the exception consists of creating the exception object & initializing it, initialization
1406 // will leave the VM via a JavaCall and then all locks must be unlocked).
1408 // The thread is still suspended when we reach here. Thread must be explicit started
1409 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1410 // by calling Threads:add. The reason why this is not done here, is because the thread
1411 // object must be fully initialized (take a look at JVM_Start)
1414 JavaThread::~JavaThread() {
1415 if (TraceThreadEvents) {
1416 tty->print_cr("terminate thread %p", this);
1419 // JSR166 -- return the parker to the free list
1420 Parker::Release(_parker);
1423 // Free any remaining previous UnrollBlock
1424 vframeArray* old_array = vframe_array_last();
1426 if (old_array != NULL) {
1427 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1428 old_array->set_unroll_block(NULL);
1433 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1434 if (deferred != NULL) {
1435 // This can only happen if thread is destroyed before deoptimization occurs.
1436 assert(deferred->length() != 0, "empty array!");
1438 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1439 deferred->remove_at(0);
1440 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1442 } while (deferred->length() != 0);
1446 // All Java related clean up happens in exit
1447 ThreadSafepointState::destroy(this);
1448 if (_thread_profiler != NULL) delete _thread_profiler;
1449 if (_thread_stat != NULL) delete _thread_stat;
1453 // The first routine called by a new Java thread
1454 void JavaThread::run() {
1455 // initialize thread-local alloc buffer related fields
1456 this->initialize_tlab();
1458 // used to test validitity of stack trace backs
1459 this->record_base_of_stack_pointer();
1461 // Record real stack base and size.
1462 this->record_stack_base_and_size();
1464 // Initialize thread local storage; set before calling MutexLocker
1465 this->initialize_thread_local_storage();
1467 this->create_stack_guard_pages();
1469 this->cache_global_variables();
1471 // Thread is now sufficient initialized to be handled by the safepoint code as being
1472 // in the VM. Change thread state from _thread_new to _thread_in_vm
1473 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1475 assert(JavaThread::current() == this, "sanity check");
1476 assert(!Thread::current()->owns_locks(), "sanity check");
1478 DTRACE_THREAD_PROBE(start, this);
1480 // This operation might block. We call that after all safepoint checks for a new thread has
1482 this->set_active_handles(JNIHandleBlock::allocate_block());
1484 if (JvmtiExport::should_post_thread_life()) {
1485 JvmtiExport::post_thread_start(this);
1488 // We call another function to do the rest so we are sure that the stack addresses used
1489 // from there will be lower than the stack base just computed
1490 thread_main_inner();
1492 // Note, thread is no longer valid at this point!
1496 void JavaThread::thread_main_inner() {
1497 assert(JavaThread::current() == this, "sanity check");
1498 assert(this->threadObj() != NULL, "just checking");
1500 // Execute thread entry point. If this thread is being asked to restart,
1501 // or has been stopped before starting, do not reexecute entry point.
1502 // Note: Due to JVM_StopThread we can have pending exceptions already!
1503 if (!this->has_pending_exception() && !java_lang_Thread::is_stillborn(this->threadObj())) {
1504 // enter the thread's entry point only if we have no pending exceptions
1505 HandleMark hm(this);
1506 this->entry_point()(this, this);
1509 DTRACE_THREAD_PROBE(stop, this);
1516 static void ensure_join(JavaThread* thread) {
1517 // We do not need to grap the Threads_lock, since we are operating on ourself.
1518 Handle threadObj(thread, thread->threadObj());
1519 assert(threadObj.not_null(), "java thread object must exist");
1520 ObjectLocker lock(threadObj, thread);
1521 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1522 thread->clear_pending_exception();
1523 // It is of profound importance that we set the stillborn bit and reset the thread object,
1524 // before we do the notify. Since, changing these two variable will make JVM_IsAlive return
1525 // false. So in case another thread is doing a join on this thread , it will detect that the thread
1526 // is dead when it gets notified.
1527 java_lang_Thread::set_stillborn(threadObj());
1528 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1529 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1530 java_lang_Thread::set_thread(threadObj(), NULL);
1531 lock.notify_all(thread);
1532 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1533 thread->clear_pending_exception();
1537 // For any new cleanup additions, please check to see if they need to be applied to
1538 // cleanup_failed_attach_current_thread as well.
1539 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1540 assert(this == JavaThread::current(), "thread consistency check");
1541 if (!InitializeJavaLangSystem) return;
1543 HandleMark hm(this);
1544 Handle uncaught_exception(this, this->pending_exception());
1545 this->clear_pending_exception();
1546 Handle threadObj(this, this->threadObj());
1547 assert(threadObj.not_null(), "Java thread object should be created");
1549 if (get_thread_profiler() != NULL) {
1550 get_thread_profiler()->disengage();
1552 get_thread_profiler()->print(get_thread_name());
1556 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1560 CLEAR_PENDING_EXCEPTION;
1562 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This
1563 // has to be fixed by a runtime query method
1564 if (!destroy_vm || JDK_Version::is_jdk12x_version()) {
1565 // JSR-166: change call from from ThreadGroup.uncaughtException to
1566 // java.lang.Thread.dispatchUncaughtException
1567 if (uncaught_exception.not_null()) {
1568 Handle group(this, java_lang_Thread::threadGroup(threadObj()));
1569 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",
1570 (address)uncaught_exception(), (address)threadObj(), (address)group());
1573 // Check if the method Thread.dispatchUncaughtException() exists. If so
1574 // call it. Otherwise we have an older library without the JSR-166 changes,
1575 // so call ThreadGroup.uncaughtException()
1576 KlassHandle recvrKlass(THREAD, threadObj->klass());
1578 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1579 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,
1580 vmSymbolHandles::dispatchUncaughtException_name(),
1581 vmSymbolHandles::throwable_void_signature(),
1582 KlassHandle(), false, false, THREAD);
1583 CLEAR_PENDING_EXCEPTION;
1584 methodHandle method = callinfo.selected_method();
1585 if (method.not_null()) {
1586 JavaValue result(T_VOID);
1587 JavaCalls::call_virtual(&result,
1588 threadObj, thread_klass,
1589 vmSymbolHandles::dispatchUncaughtException_name(),
1590 vmSymbolHandles::throwable_void_signature(),
1594 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());
1595 JavaValue result(T_VOID);
1596 JavaCalls::call_virtual(&result,
1597 group, thread_group,
1598 vmSymbolHandles::uncaughtException_name(),
1599 vmSymbolHandles::thread_throwable_void_signature(),
1601 uncaught_exception, // Arg 2
1604 CLEAR_PENDING_EXCEPTION;
1608 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1609 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1610 // is deprecated anyhow.
1612 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1614 JavaValue result(T_VOID);
1615 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1616 JavaCalls::call_virtual(&result,
1617 threadObj, thread_klass,
1618 vmSymbolHandles::exit_method_name(),
1619 vmSymbolHandles::void_method_signature(),
1621 CLEAR_PENDING_EXCEPTION;
1626 if (JvmtiExport::should_post_thread_life()) {
1627 JvmtiExport::post_thread_end(this);
1630 // We have notified the agents that we are exiting, before we go on,
1631 // we must check for a pending external suspend request and honor it
1632 // in order to not surprise the thread that made the suspend request.
1635 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1636 if (!is_external_suspend()) {
1637 set_terminated(_thread_exiting);
1638 ThreadService::current_thread_exiting(this);
1642 // Things get a little tricky here. We have a pending external
1643 // suspend request, but we are holding the SR_lock so we
1644 // can't just self-suspend. So we temporarily drop the lock
1645 // and then self-suspend.
1648 ThreadBlockInVM tbivm(this);
1649 java_suspend_self();
1651 // We're done with this suspend request, but we have to loop around
1652 // and check again. Eventually we will get SR_lock without a pending
1653 // external suspend request and will be able to mark ourselves as
1656 // no more external suspends are allowed at this point
1658 // before_exit() has already posted JVMTI THREAD_END events
1661 // Notify waiters on thread object. This has to be done after exit() is called
1662 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1663 // group should have the destroyed bit set before waiters are notified).
1665 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1667 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1668 // held by this thread must be released. A detach operation must only
1669 // get here if there are no Java frames on the stack. Therefore, any
1670 // owned monitors at this point MUST be JNI-acquired monitors which are
1671 // pre-inflated and in the monitor cache.
1673 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1674 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1675 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1676 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1677 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1680 // These things needs to be done while we are still a Java Thread. Make sure that thread
1681 // is in a consistent state, in case GC happens
1682 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1684 if (active_handles() != NULL) {
1685 JNIHandleBlock* block = active_handles();
1686 set_active_handles(NULL);
1687 JNIHandleBlock::release_block(block);
1690 if (free_handle_block() != NULL) {
1691 JNIHandleBlock* block = free_handle_block();
1692 set_free_handle_block(NULL);
1693 JNIHandleBlock::release_block(block);
1696 // These have to be removed while this is still a valid thread.
1697 remove_stack_guard_pages();
1700 tlab().make_parsable(true); // retire TLAB
1703 if (jvmti_thread_state() != NULL) {
1704 JvmtiExport::cleanup_thread(this);
1708 // We must flush G1-related buffers before removing a thread from
1709 // the list of active threads.
1711 flush_barrier_queues();
1715 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1716 Threads::remove(this);
1720 // Flush G1-related queues.
1721 void JavaThread::flush_barrier_queues() {
1722 satb_mark_queue().flush();
1723 dirty_card_queue().flush();
1726 void JavaThread::initialize_queues() {
1727 assert(!SafepointSynchronize::is_at_safepoint(),
1728 "we should not be at a safepoint");
1730 ObjPtrQueue& satb_queue = satb_mark_queue();
1731 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1732 // The SATB queue should have been constructed with its active
1733 // field set to false.
1734 assert(!satb_queue.is_active(), "SATB queue should not be active");
1735 assert(satb_queue.is_empty(), "SATB queue should be empty");
1736 // If we are creating the thread during a marking cycle, we should
1737 // set the active field of the SATB queue to true.
1738 if (satb_queue_set.is_active()) {
1739 satb_queue.set_active(true);
1742 DirtyCardQueue& dirty_queue = dirty_card_queue();
1743 // The dirty card queue should have been constructed with its
1744 // active field set to true.
1745 assert(dirty_queue.is_active(), "dirty card queue should be active");
1749 void JavaThread::cleanup_failed_attach_current_thread() {
1750 if (get_thread_profiler() != NULL) {
1751 get_thread_profiler()->disengage();
1753 get_thread_profiler()->print(get_thread_name());
1756 if (active_handles() != NULL) {
1757 JNIHandleBlock* block = active_handles();
1758 set_active_handles(NULL);
1759 JNIHandleBlock::release_block(block);
1762 if (free_handle_block() != NULL) {
1763 JNIHandleBlock* block = free_handle_block();
1764 set_free_handle_block(NULL);
1765 JNIHandleBlock::release_block(block);
1768 // These have to be removed while this is still a valid thread.
1769 remove_stack_guard_pages();
1772 tlab().make_parsable(true); // retire TLAB, if any
1777 flush_barrier_queues();
1781 Threads::remove(this);
1788 JavaThread* JavaThread::active() {
1789 Thread* thread = ThreadLocalStorage::thread();
1790 assert(thread != NULL, "just checking");
1791 if (thread->is_Java_thread()) {
1792 return (JavaThread*) thread;
1794 assert(thread->is_VM_thread(), "this must be a vm thread");
1795 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1796 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1797 assert(ret->is_Java_thread(), "must be a Java thread");
1802 bool JavaThread::is_lock_owned(address adr) const {
1803 if (Thread::is_lock_owned(adr)) return true;
1805 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1806 if (chunk->contains(adr)) return true;
1813 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1814 chunk->set_next(monitor_chunks());
1815 set_monitor_chunks(chunk);
1818 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1819 guarantee(monitor_chunks() != NULL, "must be non empty");
1820 if (monitor_chunks() == chunk) {
1821 set_monitor_chunks(chunk->next());
1823 MonitorChunk* prev = monitor_chunks();
1824 while (prev->next() != chunk) prev = prev->next();
1825 prev->set_next(chunk->next());
1831 // Note: this function shouldn't block if it's called in
1832 // _thread_in_native_trans state (such as from
1833 // check_special_condition_for_native_trans()).
1834 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1836 if (has_last_Java_frame() && has_async_condition()) {
1837 // If we are at a polling page safepoint (not a poll return)
1838 // then we must defer async exception because live registers
1839 // will be clobbered by the exception path. Poll return is
1840 // ok because the call we a returning from already collides
1841 // with exception handling registers and so there is no issue.
1842 // (The exception handling path kills call result registers but
1843 // this is ok since the exception kills the result anyway).
1845 if (is_at_poll_safepoint()) {
1846 // if the code we are returning to has deoptimized we must defer
1847 // the exception otherwise live registers get clobbered on the
1848 // exception path before deoptimization is able to retrieve them.
1850 RegisterMap map(this, false);
1851 frame caller_fr = last_frame().sender(&map);
1852 assert(caller_fr.is_compiled_frame(), "what?");
1853 if (caller_fr.is_deoptimized_frame()) {
1854 if (TraceExceptions) {
1856 tty->print_cr("deferred async exception at compiled safepoint");
1863 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
1864 if (condition == _no_async_condition) {
1865 // Conditions have changed since has_special_runtime_exit_condition()
1867 // - if we were here only because of an external suspend request,
1868 // then that was taken care of above (or cancelled) so we are done
1869 // - if we were here because of another async request, then it has
1870 // been cleared between the has_special_runtime_exit_condition()
1871 // and now so again we are done
1875 // Check for pending async. exception
1876 if (_pending_async_exception != NULL) {
1877 // Only overwrite an already pending exception, if it is not a threadDeath.
1878 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
1880 // We cannot call Exceptions::_throw(...) here because we cannot block
1881 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
1883 if (TraceExceptions) {
1885 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
1886 if (has_last_Java_frame() ) {
1887 frame f = last_frame();
1888 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
1890 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
1892 _pending_async_exception = NULL;
1893 clear_has_async_exception();
1897 if (check_unsafe_error &&
1898 condition == _async_unsafe_access_error && !has_pending_exception()) {
1899 condition = _no_async_condition; // done
1900 switch (thread_state()) {
1903 JavaThread* THREAD = this;
1904 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1906 case _thread_in_native:
1908 ThreadInVMfromNative tiv(this);
1909 JavaThread* THREAD = this;
1910 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
1912 case _thread_in_Java:
1914 ThreadInVMfromJava tiv(this);
1915 JavaThread* THREAD = this;
1916 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
1919 ShouldNotReachHere();
1923 assert(condition == _no_async_condition || has_pending_exception() ||
1924 (!check_unsafe_error && condition == _async_unsafe_access_error),
1925 "must have handled the async condition, if no exception");
1928 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
1930 // Check for pending external suspend. Internal suspend requests do
1931 // not use handle_special_runtime_exit_condition().
1932 // If JNIEnv proxies are allowed, don't self-suspend if the target
1933 // thread is not the current thread. In older versions of jdbx, jdbx
1934 // threads could call into the VM with another thread's JNIEnv so we
1935 // can be here operating on behalf of a suspended thread (4432884).
1936 bool do_self_suspend = is_external_suspend_with_lock();
1937 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
1939 // Because thread is external suspended the safepoint code will count
1940 // thread as at a safepoint. This can be odd because we can be here
1941 // as _thread_in_Java which would normally transition to _thread_blocked
1942 // at a safepoint. We would like to mark the thread as _thread_blocked
1943 // before calling java_suspend_self like all other callers of it but
1944 // we must then observe proper safepoint protocol. (We can't leave
1945 // _thread_blocked with a safepoint in progress). However we can be
1946 // here as _thread_in_native_trans so we can't use a normal transition
1947 // constructor/destructor pair because they assert on that type of
1948 // transition. We could do something like:
1950 // JavaThreadState state = thread_state();
1951 // set_thread_state(_thread_in_vm);
1953 // ThreadBlockInVM tbivm(this);
1954 // java_suspend_self()
1956 // set_thread_state(_thread_in_vm_trans);
1957 // if (safepoint) block;
1958 // set_thread_state(state);
1960 // but that is pretty messy. Instead we just go with the way the
1961 // code has worked before and note that this is the only path to
1962 // java_suspend_self that doesn't put the thread in _thread_blocked
1965 frame_anchor()->make_walkable(this);
1966 java_suspend_self();
1968 // We might be here for reasons in addition to the self-suspend request
1969 // so check for other async requests.
1973 check_and_handle_async_exceptions();
1977 void JavaThread::send_thread_stop(oop java_throwable) {
1978 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
1979 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
1980 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
1982 // Do not throw asynchronous exceptions against the compiler thread
1983 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
1984 if (is_Compiler_thread()) return;
1986 // This is a change from JDK 1.1, but JDK 1.2 will also do it:
1987 if (java_throwable->is_a(SystemDictionary::ThreadDeath_klass())) {
1988 java_lang_Thread::set_stillborn(threadObj());
1992 // Actually throw the Throwable against the target Thread - however
1993 // only if there is no thread death exception installed already.
1994 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
1995 // If the topmost frame is a runtime stub, then we are calling into
1996 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1997 // must deoptimize the caller before continuing, as the compiled exception handler table
1999 if (has_last_Java_frame()) {
2000 frame f = last_frame();
2001 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2002 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2003 RegisterMap reg_map(this, UseBiasedLocking);
2004 frame compiled_frame = f.sender(®_map);
2005 if (compiled_frame.can_be_deoptimized()) {
2006 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2011 // Set async. pending exception in thread.
2012 set_pending_async_exception(java_throwable);
2014 if (TraceExceptions) {
2016 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());
2018 // for AbortVMOnException flag
2019 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));
2024 // Interrupt thread so it will wake up from a potential wait()
2025 Thread::interrupt(this);
2028 // External suspension mechanism.
2030 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2031 // to any VM_locks and it is at a transition
2032 // Self-suspension will happen on the transition out of the vm.
2033 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2035 // Guarantees on return:
2036 // + Target thread will not execute any new bytecode (that's why we need to
2037 // force a safepoint)
2038 // + Target thread will not enter any new monitors
2040 void JavaThread::java_suspend() {
2041 { MutexLocker mu(Threads_lock);
2042 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2047 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2048 if (!is_external_suspend()) {
2049 // a racing resume has cancelled us; bail out now
2054 uint32_t debug_bits = 0;
2055 // Warning: is_ext_suspend_completed() may temporarily drop the
2056 // SR_lock to allow the thread to reach a stable thread state if
2057 // it is currently in a transient thread state.
2058 if (is_ext_suspend_completed(false /* !called_by_wait */,
2059 SuspendRetryDelay, &debug_bits) ) {
2064 VM_ForceSafepoint vm_suspend;
2065 VMThread::execute(&vm_suspend);
2068 // Part II of external suspension.
2069 // A JavaThread self suspends when it detects a pending external suspend
2070 // request. This is usually on transitions. It is also done in places
2071 // where continuing to the next transition would surprise the caller,
2072 // e.g., monitor entry.
2074 // Returns the number of times that the thread self-suspended.
2076 // Note: DO NOT call java_suspend_self() when you just want to block current
2077 // thread. java_suspend_self() is the second stage of cooperative
2078 // suspension for external suspend requests and should only be used
2079 // to complete an external suspend request.
2081 int JavaThread::java_suspend_self() {
2084 // we are in the process of exiting so don't suspend
2086 clear_external_suspend();
2090 assert(_anchor.walkable() ||
2091 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2092 "must have walkable stack");
2094 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2096 assert(!this->is_ext_suspended(),
2097 "a thread trying to self-suspend should not already be suspended");
2099 if (this->is_suspend_equivalent()) {
2100 // If we are self-suspending as a result of the lifting of a
2101 // suspend equivalent condition, then the suspend_equivalent
2102 // flag is not cleared until we set the ext_suspended flag so
2103 // that wait_for_ext_suspend_completion() returns consistent
2105 this->clear_suspend_equivalent();
2108 // A racing resume may have cancelled us before we grabbed SR_lock
2109 // above. Or another external suspend request could be waiting for us
2110 // by the time we return from SR_lock()->wait(). The thread
2111 // that requested the suspension may already be trying to walk our
2112 // stack and if we return now, we can change the stack out from under
2113 // it. This would be a "bad thing (TM)" and cause the stack walker
2114 // to crash. We stay self-suspended until there are no more pending
2115 // external suspend requests.
2116 while (is_external_suspend()) {
2118 this->set_ext_suspended();
2120 // _ext_suspended flag is cleared by java_resume()
2121 while (is_ext_suspended()) {
2122 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2130 // verify the JavaThread has not yet been published in the Threads::list, and
2131 // hence doesn't need protection from concurrent access at this stage
2132 void JavaThread::verify_not_published() {
2133 if (!Threads_lock->owned_by_self()) {
2134 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2135 assert( !Threads::includes(this),
2136 "java thread shouldn't have been published yet!");
2139 assert( !Threads::includes(this),
2140 "java thread shouldn't have been published yet!");
2145 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2146 // progress or when _suspend_flags is non-zero.
2147 // Current thread needs to self-suspend if there is a suspend request and/or
2148 // block if a safepoint is in progress.
2149 // Async exception ISN'T checked.
2150 // Note only the ThreadInVMfromNative transition can call this function
2151 // directly and when thread state is _thread_in_native_trans
2152 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2153 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2155 JavaThread *curJT = JavaThread::current();
2156 bool do_self_suspend = thread->is_external_suspend();
2158 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2160 // If JNIEnv proxies are allowed, don't self-suspend if the target
2161 // thread is not the current thread. In older versions of jdbx, jdbx
2162 // threads could call into the VM with another thread's JNIEnv so we
2163 // can be here operating on behalf of a suspended thread (4432884).
2164 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2165 JavaThreadState state = thread->thread_state();
2167 // We mark this thread_blocked state as a suspend-equivalent so
2168 // that a caller to is_ext_suspend_completed() won't be confused.
2169 // The suspend-equivalent state is cleared by java_suspend_self().
2170 thread->set_suspend_equivalent();
2172 // If the safepoint code sees the _thread_in_native_trans state, it will
2173 // wait until the thread changes to other thread state. There is no
2174 // guarantee on how soon we can obtain the SR_lock and complete the
2175 // self-suspend request. It would be a bad idea to let safepoint wait for
2176 // too long. Temporarily change the state to _thread_blocked to
2177 // let the VM thread know that this thread is ready for GC. The problem
2178 // of changing thread state is that safepoint could happen just after
2179 // java_suspend_self() returns after being resumed, and VM thread will
2180 // see the _thread_blocked state. We must check for safepoint
2181 // after restoring the state and make sure we won't leave while a safepoint
2183 thread->set_thread_state(_thread_blocked);
2184 thread->java_suspend_self();
2185 thread->set_thread_state(state);
2186 // Make sure new state is seen by VM thread
2189 // Force a fence between the write above and read below
2190 OrderAccess::fence();
2192 // Must use this rather than serialization page in particular on Windows
2193 InterfaceSupport::serialize_memory(thread);
2198 if (SafepointSynchronize::do_call_back()) {
2199 // If we are safepointing, then block the caller which may not be
2200 // the same as the target thread (see above).
2201 SafepointSynchronize::block(curJT);
2204 if (thread->is_deopt_suspend()) {
2205 thread->clear_deopt_suspend();
2206 RegisterMap map(thread, false);
2207 frame f = thread->last_frame();
2208 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2211 if (f.id() == thread->must_deopt_id()) {
2212 thread->clear_must_deopt_id();
2213 f.deoptimize(thread);
2215 fatal("missed deoptimization!");
2220 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2221 // progress or when _suspend_flags is non-zero.
2222 // Current thread needs to self-suspend if there is a suspend request and/or
2223 // block if a safepoint is in progress.
2224 // Also check for pending async exception (not including unsafe access error).
2225 // Note only the native==>VM/Java barriers can call this function and when
2226 // thread state is _thread_in_native_trans.
2227 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2228 check_safepoint_and_suspend_for_native_trans(thread);
2230 if (thread->has_async_exception()) {
2231 // We are in _thread_in_native_trans state, don't handle unsafe
2232 // access error since that may block.
2233 thread->check_and_handle_async_exceptions(false);
2237 // We need to guarantee the Threads_lock here, since resumes are not
2238 // allowed during safepoint synchronization
2239 // Can only resume from an external suspension
2240 void JavaThread::java_resume() {
2241 assert_locked_or_safepoint(Threads_lock);
2243 // Sanity check: thread is gone, has started exiting or the thread
2244 // was not externally suspended.
2245 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2249 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2251 clear_external_suspend();
2253 if (is_ext_suspended()) {
2254 clear_ext_suspended();
2255 SR_lock()->notify_all();
2259 void JavaThread::create_stack_guard_pages() {
2260 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2261 address low_addr = stack_base() - stack_size();
2262 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2264 int allocate = os::allocate_stack_guard_pages();
2265 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2267 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2268 warning("Attempt to allocate stack guard pages failed.");
2272 if (os::guard_memory((char *) low_addr, len)) {
2273 _stack_guard_state = stack_guard_enabled;
2275 warning("Attempt to protect stack guard pages failed.");
2276 if (os::uncommit_memory((char *) low_addr, len)) {
2277 warning("Attempt to deallocate stack guard pages failed.");
2282 void JavaThread::remove_stack_guard_pages() {
2283 if (_stack_guard_state == stack_guard_unused) return;
2284 address low_addr = stack_base() - stack_size();
2285 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2287 if (os::allocate_stack_guard_pages()) {
2288 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2289 _stack_guard_state = stack_guard_unused;
2291 warning("Attempt to deallocate stack guard pages failed.");
2294 if (_stack_guard_state == stack_guard_unused) return;
2295 if (os::unguard_memory((char *) low_addr, len)) {
2296 _stack_guard_state = stack_guard_unused;
2298 warning("Attempt to unprotect stack guard pages failed.");
2303 void JavaThread::enable_stack_yellow_zone() {
2304 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2305 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2307 // The base notation is from the stacks point of view, growing downward.
2308 // We need to adjust it to work correctly with guard_memory()
2309 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2311 guarantee(base < stack_base(),"Error calculating stack yellow zone");
2312 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");
2314 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2315 _stack_guard_state = stack_guard_enabled;
2317 warning("Attempt to guard stack yellow zone failed.");
2319 enable_register_stack_guard();
2322 void JavaThread::disable_stack_yellow_zone() {
2323 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2324 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2326 // Simply return if called for a thread that does not use guard pages.
2327 if (_stack_guard_state == stack_guard_unused) return;
2329 // The base notation is from the stacks point of view, growing downward.
2330 // We need to adjust it to work correctly with guard_memory()
2331 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2333 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2334 _stack_guard_state = stack_guard_yellow_disabled;
2336 warning("Attempt to unguard stack yellow zone failed.");
2338 disable_register_stack_guard();
2341 void JavaThread::enable_stack_red_zone() {
2342 // The base notation is from the stacks point of view, growing downward.
2343 // We need to adjust it to work correctly with guard_memory()
2344 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2345 address base = stack_red_zone_base() - stack_red_zone_size();
2347 guarantee(base < stack_base(),"Error calculating stack red zone");
2348 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");
2350 if(!os::guard_memory((char *) base, stack_red_zone_size())) {
2351 warning("Attempt to guard stack red zone failed.");
2355 void JavaThread::disable_stack_red_zone() {
2356 // The base notation is from the stacks point of view, growing downward.
2357 // We need to adjust it to work correctly with guard_memory()
2358 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2359 address base = stack_red_zone_base() - stack_red_zone_size();
2360 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2361 warning("Attempt to unguard stack red zone failed.");
2365 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2366 // ignore is there is no stack
2367 if (!has_last_Java_frame()) return;
2368 // traverse the stack frames. Starts from top frame.
2369 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2370 frame* fr = fst.current();
2371 f(fr, fst.register_map());
2378 // Function for testing deoptimization
2379 void JavaThread::deoptimize() {
2380 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2381 StackFrameStream fst(this, UseBiasedLocking);
2382 bool deopt = false; // Dump stack only if a deopt actually happens.
2383 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2384 // Iterate over all frames in the thread and deoptimize
2385 for(; !fst.is_done(); fst.next()) {
2386 if(fst.current()->can_be_deoptimized()) {
2389 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2390 // consists of comma or carriage return separated numbers so
2391 // search for the current bci in that string.
2392 address pc = fst.current()->pc();
2393 nmethod* nm = (nmethod*) fst.current()->cb();
2394 ScopeDesc* sd = nm->scope_desc_at( pc);
2396 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2397 size_t len = strlen(buffer);
2398 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2399 while (found != NULL) {
2400 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2401 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2402 // Check that the bci found is bracketed by terminators.
2405 found = strstr(found + 1, buffer);
2412 if (DebugDeoptimization && !deopt) {
2413 deopt = true; // One-time only print before deopt
2414 tty->print_cr("[BEFORE Deoptimization]");
2418 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2422 if (DebugDeoptimization && deopt) {
2423 tty->print_cr("[AFTER Deoptimization]");
2430 void JavaThread::make_zombies() {
2431 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2432 if (fst.current()->can_be_deoptimized()) {
2433 // it is a Java nmethod
2434 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2435 nm->make_not_entrant();
2442 void JavaThread::deoptimized_wrt_marked_nmethods() {
2443 if (!has_last_Java_frame()) return;
2444 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2445 StackFrameStream fst(this, UseBiasedLocking);
2446 for(; !fst.is_done(); fst.next()) {
2447 if (fst.current()->should_be_deoptimized()) {
2448 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2455 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }
2457 void JavaThread::gc_epilogue() {
2458 frames_do(frame_gc_epilogue);
2462 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }
2464 void JavaThread::gc_prologue() {
2465 frames_do(frame_gc_prologue);
2468 // If the caller is a NamedThread, then remember, in the current scope,
2469 // the given JavaThread in its _processed_thread field.
2470 class RememberProcessedThread: public StackObj {
2471 NamedThread* _cur_thr;
2473 RememberProcessedThread(JavaThread* jthr) {
2474 Thread* thread = Thread::current();
2475 if (thread->is_Named_thread()) {
2476 _cur_thr = (NamedThread *)thread;
2477 _cur_thr->set_processed_thread(jthr);
2483 ~RememberProcessedThread() {
2485 _cur_thr->set_processed_thread(NULL);
2490 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2491 // Verify that the deferred card marks have been flushed.
2492 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2494 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2495 // since there may be more than one thread using each ThreadProfiler.
2497 // Traverse the GCHandles
2498 Thread::oops_do(f, cf);
2500 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2501 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2503 if (has_last_Java_frame()) {
2504 // Record JavaThread to GC thread
2505 RememberProcessedThread rpt(this);
2507 // Traverse the privileged stack
2508 if (_privileged_stack_top != NULL) {
2509 _privileged_stack_top->oops_do(f);
2512 // traverse the registered growable array
2513 if (_array_for_gc != NULL) {
2514 for (int index = 0; index < _array_for_gc->length(); index++) {
2515 f->do_oop(_array_for_gc->adr_at(index));
2519 // Traverse the monitor chunks
2520 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2524 // Traverse the execution stack
2525 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2526 fst.current()->oops_do(f, cf, fst.register_map());
2530 // callee_target is never live across a gc point so NULL it here should
2531 // it still contain a methdOop.
2533 set_callee_target(NULL);
2535 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2536 // If we have deferred set_locals there might be oops waiting to be
2538 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2540 for (int i = 0; i < list->length(); i++) {
2541 list->at(i)->oops_do(f);
2545 // Traverse instance variables at the end since the GC may be moving things
2546 // around using this function
2547 f->do_oop((oop*) &_threadObj);
2548 f->do_oop((oop*) &_vm_result);
2549 f->do_oop((oop*) &_vm_result_2);
2550 f->do_oop((oop*) &_exception_oop);
2551 f->do_oop((oop*) &_pending_async_exception);
2553 if (jvmti_thread_state() != NULL) {
2554 jvmti_thread_state()->oops_do(f);
2558 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2559 Thread::nmethods_do(cf); // (super method is a no-op)
2561 assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
2562 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2564 if (has_last_Java_frame()) {
2565 // Traverse the execution stack
2566 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2567 fst.current()->nmethods_do(cf);
2573 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2574 switch (_thread_state) {
2575 case _thread_uninitialized: return "_thread_uninitialized";
2576 case _thread_new: return "_thread_new";
2577 case _thread_new_trans: return "_thread_new_trans";
2578 case _thread_in_native: return "_thread_in_native";
2579 case _thread_in_native_trans: return "_thread_in_native_trans";
2580 case _thread_in_vm: return "_thread_in_vm";
2581 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2582 case _thread_in_Java: return "_thread_in_Java";
2583 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2584 case _thread_blocked: return "_thread_blocked";
2585 case _thread_blocked_trans: return "_thread_blocked_trans";
2586 default: return "unknown thread state";
2591 void JavaThread::print_thread_state_on(outputStream *st) const {
2592 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2594 void JavaThread::print_thread_state() const {
2595 print_thread_state_on(tty);
2599 // Called by Threads::print() for VM_PrintThreads operation
2600 void JavaThread::print_on(outputStream *st) const {
2601 st->print("\"%s\" ", get_thread_name());
2602 oop thread_oop = threadObj();
2603 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2604 Thread::print_on(st);
2605 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2606 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2607 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {
2608 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2611 print_thread_state_on(st);
2612 _safepoint_state->print_on(st);
2616 // Called by fatal error handler. The difference between this and
2617 // JavaThread::print() is that we can't grab lock or allocate memory.
2618 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2619 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2620 oop thread_obj = threadObj();
2621 if (thread_obj != NULL) {
2622 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2625 st->print("%s", _get_thread_state_name(_thread_state));
2627 st->print(", id=%d", osthread()->thread_id());
2629 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2630 _stack_base - _stack_size, _stack_base);
2637 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2639 void JavaThread::verify() {
2640 // Verify oops in the thread.
2641 oops_do(&VerifyOopClosure::verify_oop, NULL);
2643 // Verify the stack frames.
2644 frames_do(frame_verify);
2647 // CR 6300358 (sub-CR 2137150)
2648 // Most callers of this method assume that it can't return NULL but a
2649 // thread may not have a name whilst it is in the process of attaching to
2650 // the VM - see CR 6412693, and there are places where a JavaThread can be
2651 // seen prior to having it's threadObj set (eg JNI attaching threads and
2652 // if vm exit occurs during initialization). These cases can all be accounted
2653 // for such that this method never returns NULL.
2654 const char* JavaThread::get_thread_name() const {
2656 // early safepoints can hit while current thread does not yet have TLS
2657 if (!SafepointSynchronize::is_at_safepoint()) {
2658 Thread *cur = Thread::current();
2659 if (!(cur->is_Java_thread() && cur == this)) {
2660 // Current JavaThreads are allowed to get their own name without
2661 // the Threads_lock.
2662 assert_locked_or_safepoint(Threads_lock);
2666 return get_thread_name_string();
2669 // Returns a non-NULL representation of this thread's name, or a suitable
2670 // descriptive string if there is no set name
2671 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2672 const char* name_str;
2673 oop thread_obj = threadObj();
2674 if (thread_obj != NULL) {
2675 typeArrayOop name = java_lang_Thread::name(thread_obj);
2678 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2681 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen);
2684 else if (is_attaching()) { // workaround for 6412693 - see 6404306
2685 name_str = "<no-name - thread is attaching>";
2688 name_str = Thread::name();
2692 name_str = Thread::name();
2694 assert(name_str != NULL, "unexpected NULL thread name");
2699 const char* JavaThread::get_threadgroup_name() const {
2700 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2701 oop thread_obj = threadObj();
2702 if (thread_obj != NULL) {
2703 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2704 if (thread_group != NULL) {
2705 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2706 // ThreadGroup.name can be null
2708 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2716 const char* JavaThread::get_parent_name() const {
2717 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2718 oop thread_obj = threadObj();
2719 if (thread_obj != NULL) {
2720 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2721 if (thread_group != NULL) {
2722 oop parent = java_lang_ThreadGroup::parent(thread_group);
2723 if (parent != NULL) {
2724 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2725 // ThreadGroup.name can be null
2727 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2736 ThreadPriority JavaThread::java_priority() const {
2737 oop thr_oop = threadObj();
2738 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2739 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2740 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2744 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2746 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2747 // Link Java Thread object <-> C++ Thread
2749 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2750 // and put it into a new Handle. The Handle "thread_oop" can then
2751 // be used to pass the C++ thread object to other methods.
2753 // Set the Java level thread object (jthread) field of the
2754 // new thread (a JavaThread *) to C++ thread object using the
2755 // "thread_oop" handle.
2757 // Set the thread field (a JavaThread *) of the
2758 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2760 Handle thread_oop(Thread::current(),
2761 JNIHandles::resolve_non_null(jni_thread));
2762 assert(instanceKlass::cast(thread_oop->klass())->is_linked(),
2763 "must be initialized");
2764 set_threadObj(thread_oop());
2765 java_lang_Thread::set_thread(thread_oop(), this);
2767 if (prio == NoPriority) {
2768 prio = java_lang_Thread::priority(thread_oop());
2769 assert(prio != NoPriority, "A valid priority should be present");
2772 // Push the Java priority down to the native thread; needs Threads_lock
2773 Thread::set_priority(this, prio);
2775 // Add the new thread to the Threads list and set it in motion.
2776 // We must have threads lock in order to call Threads::add.
2777 // It is crucial that we do not block before the thread is
2778 // added to the Threads list for if a GC happens, then the java_thread oop
2779 // will not be visited by GC.
2783 oop JavaThread::current_park_blocker() {
2784 // Support for JSR-166 locks
2785 oop thread_oop = threadObj();
2786 if (thread_oop != NULL &&
2787 JDK_Version::current().supports_thread_park_blocker()) {
2788 return java_lang_Thread::park_blocker(thread_oop);
2794 void JavaThread::print_stack_on(outputStream* st) {
2795 if (!has_last_Java_frame()) return;
2799 RegisterMap reg_map(this);
2800 vframe* start_vf = last_java_vframe(®_map);
2802 for (vframe* f = start_vf; f; f = f->sender() ) {
2803 if (f->is_java_frame()) {
2804 javaVFrame* jvf = javaVFrame::cast(f);
2805 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2807 // Print out lock information
2808 if (JavaMonitorsInStackTrace) {
2809 jvf->print_lock_info_on(st, count);
2812 // Ignore non-Java frames
2815 // Bail-out case for too deep stacks
2817 if (MaxJavaStackTraceDepth == count) return;
2822 // JVMTI PopFrame support
2823 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2824 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2825 if (in_bytes(size_in_bytes) != 0) {
2826 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes));
2827 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2828 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2832 void* JavaThread::popframe_preserved_args() {
2833 return _popframe_preserved_args;
2836 ByteSize JavaThread::popframe_preserved_args_size() {
2837 return in_ByteSize(_popframe_preserved_args_size);
2840 WordSize JavaThread::popframe_preserved_args_size_in_words() {
2841 int sz = in_bytes(popframe_preserved_args_size());
2842 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
2843 return in_WordSize(sz / wordSize);
2846 void JavaThread::popframe_free_preserved_args() {
2847 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
2848 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
2849 _popframe_preserved_args = NULL;
2850 _popframe_preserved_args_size = 0;
2855 void JavaThread::trace_frames() {
2856 tty->print_cr("[Describe stack]");
2858 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2859 tty->print(" %d. ", frame_no++);
2860 fst.current()->print_value_on(tty,this);
2866 void JavaThread::trace_stack_from(vframe* start_vf) {
2869 for (vframe* f = start_vf; f; f = f->sender() ) {
2870 if (f->is_java_frame()) {
2871 javaVFrame::cast(f)->print_activation(vframe_no++);
2875 if (vframe_no > StackPrintLimit) {
2876 tty->print_cr("...<more frames>...");
2883 void JavaThread::trace_stack() {
2884 if (!has_last_Java_frame()) return;
2887 RegisterMap reg_map(this);
2888 trace_stack_from(last_java_vframe(®_map));
2895 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
2896 assert(reg_map != NULL, "a map must be given");
2897 frame f = last_frame();
2898 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) {
2899 if (vf->is_java_frame()) return javaVFrame::cast(vf);
2905 klassOop JavaThread::security_get_caller_class(int depth) {
2906 vframeStream vfst(this);
2907 vfst.security_get_caller_frame(depth);
2908 if (!vfst.at_end()) {
2909 return vfst.method()->method_holder();
2914 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
2915 assert(thread->is_Compiler_thread(), "must be compiler thread");
2916 CompileBroker::compiler_thread_loop();
2919 // Create a CompilerThread
2920 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
2921 : JavaThread(&compiler_thread_entry) {
2926 _counters = counters;
2927 _buffer_blob = NULL;
2930 _ideal_graph_printer = NULL;
2935 // ======= Threads ========
2937 // The Threads class links together all active threads, and provides
2938 // operations over all threads. It is protected by its own Mutex
2939 // lock, which is also used in other contexts to protect thread
2940 // operations from having the thread being operated on from exiting
2941 // and going away unexpectedly (e.g., safepoint synchronization)
2943 JavaThread* Threads::_thread_list = NULL;
2944 int Threads::_number_of_threads = 0;
2945 int Threads::_number_of_non_daemon_threads = 0;
2946 int Threads::_return_code = 0;
2947 size_t JavaThread::_stack_size_at_create = 0;
2950 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
2954 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
2955 void Threads::threads_do(ThreadClosure* tc) {
2956 assert_locked_or_safepoint(Threads_lock);
2957 // ALL_JAVA_THREADS iterates through all JavaThreads
2958 ALL_JAVA_THREADS(p) {
2961 // Someday we could have a table or list of all non-JavaThreads.
2962 // For now, just manually iterate through them.
2963 tc->do_thread(VMThread::vm_thread());
2964 Universe::heap()->gc_threads_do(tc);
2965 WatcherThread *wt = WatcherThread::watcher_thread();
2966 // Strictly speaking, the following NULL check isn't sufficient to make sure
2967 // the data for WatcherThread is still valid upon being examined. However,
2968 // considering that WatchThread terminates when the VM is on the way to
2969 // exit at safepoint, the chance of the above is extremely small. The right
2970 // way to prevent termination of WatcherThread would be to acquire
2971 // Terminator_lock, but we can't do that without violating the lock rank
2972 // checking in some cases.
2976 // If CompilerThreads ever become non-JavaThreads, add them here
2979 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
2981 extern void JDK_Version_init();
2984 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
2986 // Initialize the output stream module
2989 // Process java launcher properties.
2990 Arguments::process_sun_java_launcher_properties(args);
2992 // Initialize the os module before using TLS
2995 // Initialize system properties.
2996 Arguments::init_system_properties();
2998 // So that JDK version can be used as a discrimintor when parsing arguments
3001 // Update/Initialize System properties after JDK version number is known
3002 Arguments::init_version_specific_system_properties();
3005 jint parse_result = Arguments::parse(args);
3006 if (parse_result != JNI_OK) return parse_result;
3008 if (PauseAtStartup) {
3012 HS_DTRACE_PROBE(hotspot, vm__init__begin);
3014 // Record VM creation timing statistics
3015 TraceVmCreationTime create_vm_timer;
3016 create_vm_timer.start();
3018 // Timing (must come after argument parsing)
3019 TraceTime timer("Create VM", TraceStartupTime);
3021 // Initialize the os module after parsing the args
3022 jint os_init_2_result = os::init_2();
3023 if (os_init_2_result != JNI_OK) return os_init_2_result;
3025 // Initialize output stream logging
3028 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3029 // Must be before create_vm_init_agents()
3030 if (Arguments::init_libraries_at_startup()) {
3031 convert_vm_init_libraries_to_agents();
3034 // Launch -agentlib/-agentpath and converted -Xrun agents
3035 if (Arguments::init_agents_at_startup()) {
3036 create_vm_init_agents();
3039 // Initialize Threads state
3040 _thread_list = NULL;
3041 _number_of_threads = 0;
3042 _number_of_non_daemon_threads = 0;
3045 ThreadLocalStorage::init();
3047 // Initialize global data structures and create system classes in heap
3050 // Attach the main thread to this os thread
3051 JavaThread* main_thread = new JavaThread();
3052 main_thread->set_thread_state(_thread_in_vm);
3053 // must do this before set_active_handles and initialize_thread_local_storage
3054 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3055 // change the stack size recorded here to one based on the java thread
3056 // stacksize. This adjusted size is what is used to figure the placement
3057 // of the guard pages.
3058 main_thread->record_stack_base_and_size();
3059 main_thread->initialize_thread_local_storage();
3061 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3063 if (!main_thread->set_as_starting_thread()) {
3064 vm_shutdown_during_initialization(
3065 "Failed necessary internal allocation. Out of swap space");
3067 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3071 // Enable guard page *after* os::create_main_thread(), otherwise it would
3072 // crash Linux VM, see notes in os_linux.cpp.
3073 main_thread->create_stack_guard_pages();
3075 // Initialize Java-Level synchronization subsystem
3076 ObjectMonitor::Initialize() ;
3078 // Initialize global modules
3079 jint status = init_globals();
3080 if (status != JNI_OK) {
3082 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3086 // Should be done after the heap is fully created
3087 main_thread->cache_global_variables();
3091 { MutexLocker mu(Threads_lock);
3092 Threads::add(main_thread);
3095 // Any JVMTI raw monitors entered in onload will transition into
3096 // real raw monitor. VM is setup enough here for raw monitor enter.
3097 JvmtiExport::transition_pending_onload_raw_monitors();
3099 if (VerifyBeforeGC &&
3100 Universe::heap()->total_collections() >= VerifyGCStartAt) {
3101 Universe::heap()->prepare_for_verify();
3102 Universe::verify(); // make sure we're starting with a clean slate
3105 // Create the VMThread
3106 { TraceTime timer("Start VMThread", TraceStartupTime);
3108 Thread* vmthread = VMThread::vm_thread();
3110 if (!os::create_thread(vmthread, os::vm_thread))
3111 vm_exit_during_initialization("Cannot create VM thread. Out of system resources.");
3113 // Wait for the VM thread to become ready, and VMThread::run to initialize
3114 // Monitors can have spurious returns, must always check another state flag
3116 MutexLocker ml(Notify_lock);
3117 os::start_thread(vmthread);
3118 while (vmthread->active_handles() == NULL) {
3119 Notify_lock->wait();
3124 assert (Universe::is_fully_initialized(), "not initialized");
3127 // At this point, the Universe is initialized, but we have not executed
3128 // any byte code. Now is a good time (the only time) to dump out the
3129 // internal state of the JVM for sharing.
3131 if (DumpSharedSpaces) {
3132 Universe::heap()->preload_and_dump(CHECK_0);
3133 ShouldNotReachHere();
3136 // Always call even when there are not JVMTI environments yet, since environments
3137 // may be attached late and JVMTI must track phases of VM execution
3138 JvmtiExport::enter_start_phase();
3140 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3141 JvmtiExport::post_vm_start();
3144 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3146 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3147 create_vm_init_libraries();
3150 if (InitializeJavaLangString) {
3151 initialize_class(vmSymbolHandles::java_lang_String(), CHECK_0);
3153 warning("java.lang.String not initialized");
3156 if (AggressiveOpts) {
3158 // Forcibly initialize java/util/HashMap and mutate the private
3159 // static final "frontCacheEnabled" field before we start creating instances
3161 klassOop tmp_k = SystemDictionary::find(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3162 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet");
3164 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_util_HashMap(), Handle(), Handle(), CHECK_0);
3165 KlassHandle k = KlassHandle(THREAD, k_o);
3166 guarantee(k.not_null(), "Must find java/util/HashMap");
3167 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3168 ik->initialize(CHECK_0);
3170 // Possible we might not find this field; if so, don't break
3171 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3172 k()->bool_field_put(fd.offset(), true);
3176 if (UseStringCache) {
3177 // Forcibly initialize java/lang/StringValue and mutate the private
3178 // static final "stringCacheEnabled" field before we start creating instances
3179 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_StringValue(), Handle(), Handle(), CHECK_0);
3180 // Possible that StringValue isn't present: if so, silently don't break
3182 KlassHandle k = KlassHandle(THREAD, k_o);
3183 instanceKlassHandle ik = instanceKlassHandle(THREAD, k());
3184 ik->initialize(CHECK_0);
3186 // Possible we might not find this field: if so, silently don't break
3187 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) {
3188 k()->bool_field_put(fd.offset(), true);
3194 // Initialize java_lang.System (needed before creating the thread)
3195 if (InitializeJavaLangSystem) {
3196 initialize_class(vmSymbolHandles::java_lang_System(), CHECK_0);
3197 initialize_class(vmSymbolHandles::java_lang_ThreadGroup(), CHECK_0);
3198 Handle thread_group = create_initial_thread_group(CHECK_0);
3199 Universe::set_main_thread_group(thread_group());
3200 initialize_class(vmSymbolHandles::java_lang_Thread(), CHECK_0);
3201 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0);
3202 main_thread->set_threadObj(thread_object);
3203 // Set thread status to running since main thread has
3204 // been started and running.
3205 java_lang_Thread::set_thread_status(thread_object,
3206 java_lang_Thread::RUNNABLE);
3208 // The VM preresolve methods to these classes. Make sure that get initialized
3209 initialize_class(vmSymbolHandles::java_lang_reflect_Method(), CHECK_0);
3210 initialize_class(vmSymbolHandles::java_lang_ref_Finalizer(), CHECK_0);
3211 // The VM creates & returns objects of this class. Make sure it's initialized.
3212 initialize_class(vmSymbolHandles::java_lang_Class(), CHECK_0);
3213 call_initializeSystemClass(CHECK_0);
3215 warning("java.lang.System not initialized");
3218 // an instance of OutOfMemory exception has been allocated earlier
3219 if (InitializeJavaLangExceptionsErrors) {
3220 initialize_class(vmSymbolHandles::java_lang_OutOfMemoryError(), CHECK_0);
3221 initialize_class(vmSymbolHandles::java_lang_NullPointerException(), CHECK_0);
3222 initialize_class(vmSymbolHandles::java_lang_ClassCastException(), CHECK_0);
3223 initialize_class(vmSymbolHandles::java_lang_ArrayStoreException(), CHECK_0);
3224 initialize_class(vmSymbolHandles::java_lang_ArithmeticException(), CHECK_0);
3225 initialize_class(vmSymbolHandles::java_lang_StackOverflowError(), CHECK_0);
3226 initialize_class(vmSymbolHandles::java_lang_IllegalMonitorStateException(), CHECK_0);
3228 warning("java.lang.OutOfMemoryError has not been initialized");
3229 warning("java.lang.NullPointerException has not been initialized");
3230 warning("java.lang.ClassCastException has not been initialized");
3231 warning("java.lang.ArrayStoreException has not been initialized");
3232 warning("java.lang.ArithmeticException has not been initialized");
3233 warning("java.lang.StackOverflowError has not been initialized");
3236 if (EnableInvokeDynamic) {
3237 // JSR 292: An intialized java.dyn.InvokeDynamic is required in
3239 initialize_class(vmSymbolHandles::java_dyn_InvokeDynamic(), CHECK_0);
3243 // See : bugid 4211085.
3244 // Background : the static initializer of java.lang.Compiler tries to read
3245 // property"java.compiler" and read & write property "java.vm.info".
3246 // When a security manager is installed through the command line
3247 // option "-Djava.security.manager", the above properties are not
3248 // readable and the static initializer for java.lang.Compiler fails
3249 // resulting in a NoClassDefFoundError. This can happen in any
3250 // user code which calls methods in java.lang.Compiler.
3251 // Hack : the hack is to pre-load and initialize this class, so that only
3252 // system domains are on the stack when the properties are read.
3253 // Currently even the AWT code has calls to methods in java.lang.Compiler.
3254 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT.
3255 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and
3256 // read and write"java.vm.info" in the default policy file. See bugid 4211383
3257 // Once that is done, we should remove this hack.
3258 initialize_class(vmSymbolHandles::java_lang_Compiler(), CHECK_0);
3260 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to
3261 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot
3262 // compiler does not get loaded through java.lang.Compiler). "java -version" with the
3263 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here.
3264 // This should also be taken out as soon as 4211383 gets fixed.
3265 reset_vm_info_property(CHECK_0);
3267 quicken_jni_functions();
3269 // Set flag that basic initialization has completed. Used by exceptions and various
3270 // debug stuff, that does not work until all basic classes have been initialized.
3271 set_init_completed();
3273 HS_DTRACE_PROBE(hotspot, vm__init__end);
3275 // record VM initialization completion time
3276 Management::record_vm_init_completed();
3278 // Compute system loader. Note that this has to occur after set_init_completed, since
3279 // valid exceptions may be thrown in the process.
3280 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3281 // set_init_completed has just been called, causing exceptions not to be shortcut
3282 // anymore. We call vm_exit_during_initialization directly instead.
3283 SystemDictionary::compute_java_system_loader(THREAD);
3284 if (HAS_PENDING_EXCEPTION) {
3285 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3289 if (JDK_Version::is_gte_jdk17x_version()) {
3290 set_jkernel_boot_classloader_hook(THREAD);
3295 // Support for ConcurrentMarkSweep. This should be cleaned up
3296 // and better encapsulated. The ugly nested if test would go away
3297 // once things are properly refactored. XXX YSR
3298 if (UseConcMarkSweepGC || UseG1GC) {
3299 if (UseConcMarkSweepGC) {
3300 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD);
3302 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD);
3304 if (HAS_PENDING_EXCEPTION) {
3305 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION));
3310 // Always call even when there are not JVMTI environments yet, since environments
3311 // may be attached late and JVMTI must track phases of VM execution
3312 JvmtiExport::enter_live_phase();
3314 // Signal Dispatcher needs to be started before VMInit event is posted
3317 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3318 if (!DisableAttachMechanism) {
3319 if (StartAttachListener || AttachListener::init_at_startup()) {
3320 AttachListener::init();
3324 // Launch -Xrun agents
3325 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3326 // back-end can launch with -Xdebug -Xrunjdwp.
3327 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3328 create_vm_init_libraries();
3331 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3332 JvmtiExport::post_vm_initialized();
3334 Chunk::start_chunk_pool_cleaner_task();
3336 // initialize compiler(s)
3337 CompileBroker::compilation_init();
3339 Management::initialize(THREAD);
3340 if (HAS_PENDING_EXCEPTION) {
3341 // management agent fails to start possibly due to
3342 // configuration problem and is responsible for printing
3343 // stack trace if appropriate. Simply exit VM.
3347 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3348 if (Arguments::has_alloc_profile()) AllocationProfiler::engage();
3349 if (MemProfiling) MemProfiler::engage();
3350 StatSampler::engage();
3351 if (CheckJNICalls) JniPeriodicChecker::engage();
3353 BiasedLocking::init();
3356 // Start up the WatcherThread if there are any periodic tasks
3357 // NOTE: All PeriodicTasks should be registered by now. If they
3358 // aren't, late joiners might appear to start slowly (we might
3359 // take a while to process their first tick).
3360 if (PeriodicTask::num_tasks() > 0) {
3361 WatcherThread::start();
3364 // Give os specific code one last chance to start
3367 create_vm_timer.end();
3371 // type for the Agent_OnLoad and JVM_OnLoad entry points
3373 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3375 // Find a command line agent library and return its entry point for
3376 // -agentlib: -agentpath: -Xrun
3377 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3378 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) {
3379 OnLoadEntry_t on_load_entry = NULL;
3380 void *library = agent->os_lib(); // check if we have looked it up before
3382 if (library == NULL) {
3383 char buffer[JVM_MAXPATHLEN];
3385 const char *name = agent->name();
3386 const char *msg = "Could not find agent library ";
3388 if (agent->is_absolute_path()) {
3389 library = hpi::dll_load(name, ebuf, sizeof ebuf);
3390 if (library == NULL) {
3391 const char *sub_msg = " in absolute path, with error: ";
3392 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3393 char *buf = NEW_C_HEAP_ARRAY(char, len);
3394 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3395 // If we can't find the agent, exit.
3396 vm_exit_during_initialization(buf, NULL);
3397 FREE_C_HEAP_ARRAY(char, buf);
3400 // Try to load the agent from the standard dll directory
3401 hpi::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name);
3402 library = hpi::dll_load(buffer, ebuf, sizeof ebuf);
3404 // Download instrument dll
3405 if (library == NULL && strcmp(name, "instrument") == 0) {
3406 char *props = Arguments::get_kernel_properties();
3407 char *home = Arguments::get_java_home();
3408 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false"
3409 " sun.jkernel.DownloadManager -download client_jvm";
3410 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1;
3411 char *cmd = NEW_C_HEAP_ARRAY(char, length);
3412 jio_snprintf(cmd, length, fmt, home, props);
3413 int status = os::fork_and_exec(cmd);
3417 vm_exit_during_initialization("fork_and_exec failed: %s",
3420 FREE_C_HEAP_ARRAY(char, cmd);
3421 // when this comes back the instrument.dll should be where it belongs.
3422 library = hpi::dll_load(buffer, ebuf, sizeof ebuf);
3425 if (library == NULL) { // Try the local directory
3427 hpi::dll_build_name(buffer, sizeof(buffer), ns, name);
3428 library = hpi::dll_load(buffer, ebuf, sizeof ebuf);
3429 if (library == NULL) {
3430 const char *sub_msg = " on the library path, with error: ";
3431 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3432 char *buf = NEW_C_HEAP_ARRAY(char, len);
3433 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3434 // If we can't find the agent, exit.
3435 vm_exit_during_initialization(buf, NULL);
3436 FREE_C_HEAP_ARRAY(char, buf);
3440 agent->set_os_lib(library);
3443 // Find the OnLoad function.
3444 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) {
3445 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, hpi::dll_lookup(library, on_load_symbols[symbol_index]));
3446 if (on_load_entry != NULL) break;
3448 return on_load_entry;
3451 // Find the JVM_OnLoad entry point
3452 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3453 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3454 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3457 // Find the Agent_OnLoad entry point
3458 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3459 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3460 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3463 // For backwards compatibility with -Xrun
3464 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3465 // treated like -agentpath:
3466 // Must be called before agent libraries are created
3467 void Threads::convert_vm_init_libraries_to_agents() {
3468 AgentLibrary* agent;
3471 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3472 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3473 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3475 // If there is an JVM_OnLoad function it will get called later,
3476 // otherwise see if there is an Agent_OnLoad
3477 if (on_load_entry == NULL) {
3478 on_load_entry = lookup_agent_on_load(agent);
3479 if (on_load_entry != NULL) {
3480 // switch it to the agent list -- so that Agent_OnLoad will be called,
3481 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3482 Arguments::convert_library_to_agent(agent);
3484 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3490 // Create agents for -agentlib: -agentpath: and converted -Xrun
3491 // Invokes Agent_OnLoad
3492 // Called very early -- before JavaThreads exist
3493 void Threads::create_vm_init_agents() {
3494 extern struct JavaVM_ main_vm;
3495 AgentLibrary* agent;
3497 JvmtiExport::enter_onload_phase();
3498 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3499 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3501 if (on_load_entry != NULL) {
3502 // Invoke the Agent_OnLoad function
3503 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3504 if (err != JNI_OK) {
3505 vm_exit_during_initialization("agent library failed to init", agent->name());
3508 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3511 JvmtiExport::enter_primordial_phase();
3515 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3518 void Threads::shutdown_vm_agents() {
3519 // Send any Agent_OnUnload notifications
3520 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3521 extern struct JavaVM_ main_vm;
3522 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3524 // Find the Agent_OnUnload function.
3525 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) {
3526 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3527 hpi::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index]));
3529 // Invoke the Agent_OnUnload function
3530 if (unload_entry != NULL) {
3531 JavaThread* thread = JavaThread::current();
3532 ThreadToNativeFromVM ttn(thread);
3533 HandleMark hm(thread);
3534 (*unload_entry)(&main_vm);
3541 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3542 // Invokes JVM_OnLoad
3543 void Threads::create_vm_init_libraries() {
3544 extern struct JavaVM_ main_vm;
3545 AgentLibrary* agent;
3547 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3548 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3550 if (on_load_entry != NULL) {
3551 // Invoke the JVM_OnLoad function
3552 JavaThread* thread = JavaThread::current();
3553 ThreadToNativeFromVM ttn(thread);
3554 HandleMark hm(thread);
3555 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3556 if (err != JNI_OK) {
3557 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3560 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3565 // Last thread running calls java.lang.Shutdown.shutdown()
3566 void JavaThread::invoke_shutdown_hooks() {
3567 HandleMark hm(this);
3569 // We could get here with a pending exception, if so clear it now.
3570 if (this->has_pending_exception()) {
3571 this->clear_pending_exception();
3576 SystemDictionary::resolve_or_null(vmSymbolHandles::java_lang_Shutdown(),
3579 // SystemDictionary::resolve_or_null will return null if there was
3580 // an exception. If we cannot load the Shutdown class, just don't
3581 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3582 // and finalizers (if runFinalizersOnExit is set) won't be run.
3583 // Note that if a shutdown hook was registered or runFinalizersOnExit
3584 // was called, the Shutdown class would have already been loaded
3585 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3586 instanceKlassHandle shutdown_klass (THREAD, k);
3587 JavaValue result(T_VOID);
3588 JavaCalls::call_static(&result,
3590 vmSymbolHandles::shutdown_method_name(),
3591 vmSymbolHandles::void_method_signature(),
3594 CLEAR_PENDING_EXCEPTION;
3597 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3598 // the program falls off the end of main(). Another VM exit path is through
3599 // vm_exit() when the program calls System.exit() to return a value or when
3600 // there is a serious error in VM. The two shutdown paths are not exactly
3601 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3602 // and VM_Exit op at VM level.
3604 // Shutdown sequence:
3605 // + Wait until we are the last non-daemon thread to execute
3606 // <-- every thing is still working at this moment -->
3607 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3608 // shutdown hooks, run finalizers if finalization-on-exit
3609 // + Call before_exit(), prepare for VM exit
3610 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3611 // currently the only user of this mechanism is File.deleteOnExit())
3612 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3613 // post thread end and vm death events to JVMTI,
3614 // stop signal thread
3615 // + Call JavaThread::exit(), it will:
3616 // > release JNI handle blocks, remove stack guard pages
3617 // > remove this thread from Threads list
3618 // <-- no more Java code from this thread after this point -->
3619 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3620 // the compiler threads at safepoint
3621 // <-- do not use anything that could get blocked by Safepoint -->
3622 // + Disable tracing at JNI/JVM barriers
3623 // + Set _vm_exited flag for threads that are still running native code
3624 // + Delete this thread
3625 // + Call exit_globals()
3627 // > deletes PerfMemory resources
3628 // + Return to caller
3630 bool Threads::destroy_vm() {
3631 JavaThread* thread = JavaThread::current();
3633 // Wait until we are the last non-daemon thread to execute
3634 { MutexLocker nu(Threads_lock);
3635 while (Threads::number_of_non_daemon_threads() > 1 )
3636 // This wait should make safepoint checks, wait without a timeout,
3637 // and wait as a suspend-equivalent condition.
3639 // Note: If the FlatProfiler is running and this thread is waiting
3640 // for another non-daemon thread to finish, then the FlatProfiler
3641 // is waiting for the external suspend request on this thread to
3642 // complete. wait_for_ext_suspend_completion() will eventually
3643 // timeout, but that takes time. Making this wait a suspend-
3644 // equivalent condition solves that timeout problem.
3646 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3647 Mutex::_as_suspend_equivalent_flag);
3650 // Hang forever on exit if we are reporting an error.
3651 if (ShowMessageBoxOnError && is_error_reported()) {
3652 os::infinite_sleep();
3655 if (JDK_Version::is_jdk12x_version()) {
3656 // We are the last thread running, so check if finalizers should be run.
3657 // For 1.3 or later this is done in thread->invoke_shutdown_hooks()
3658 HandleMark rm(thread);
3659 Universe::run_finalizers_on_exit();
3661 // run Java level shutdown hooks
3662 thread->invoke_shutdown_hooks();
3665 before_exit(thread);
3671 // 4945125 The vm thread comes to a safepoint during exit.
3672 // GC vm_operations can get caught at the safepoint, and the
3673 // heap is unparseable if they are caught. Grab the Heap_lock
3674 // to prevent this. The GC vm_operations will not be able to
3675 // queue until after the vm thread is dead.
3676 MutexLocker ml(Heap_lock);
3678 VMThread::wait_for_vm_thread_exit();
3679 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3680 VMThread::destroy();
3683 // clean up ideal graph printers
3684 #if defined(COMPILER2) && !defined(PRODUCT)
3685 IdealGraphPrinter::clean_up();
3688 // Now, all Java threads are gone except daemon threads. Daemon threads
3689 // running Java code or in VM are stopped by the Safepoint. However,
3690 // daemon threads executing native code are still running. But they
3691 // will be stopped at native=>Java/VM barriers. Note that we can't
3692 // simply kill or suspend them, as it is inherently deadlock-prone.
3695 // disable function tracing at JNI/JVM barriers
3697 TraceJNICalls = false;
3698 TraceJVMCalls = false;
3699 TraceRuntimeCalls = false;
3702 VM_Exit::set_vm_exited();
3704 notify_vm_shutdown();
3708 // exit_globals() will delete tty
3715 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3716 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3717 return is_supported_jni_version(version);
3721 jboolean Threads::is_supported_jni_version(jint version) {
3722 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3723 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3724 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3729 void Threads::add(JavaThread* p, bool force_daemon) {
3730 // The threads lock must be owned at this point
3731 assert_locked_or_safepoint(Threads_lock);
3733 // See the comment for this method in thread.hpp for its purpose and
3734 // why it is called here.
3735 p->initialize_queues();
3736 p->set_next(_thread_list);
3738 _number_of_threads++;
3739 oop threadObj = p->threadObj();
3741 // Bootstrapping problem: threadObj can be null for initial
3742 // JavaThread (or for threads attached via JNI)
3743 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3744 _number_of_non_daemon_threads++;
3748 ThreadService::add_thread(p, daemon);
3750 // Possible GC point.
3751 Events::log("Thread added: " INTPTR_FORMAT, p);
3754 void Threads::remove(JavaThread* p) {
3755 // Extra scope needed for Thread_lock, so we can check
3756 // that we do not remove thread without safepoint code notice
3757 { MutexLocker ml(Threads_lock);
3759 assert(includes(p), "p must be present");
3761 JavaThread* current = _thread_list;
3762 JavaThread* prev = NULL;
3764 while (current != p) {
3766 current = current->next();
3770 prev->set_next(current->next());
3772 _thread_list = p->next();
3774 _number_of_threads--;
3775 oop threadObj = p->threadObj();
3777 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
3778 _number_of_non_daemon_threads--;
3781 // Only one thread left, do a notify on the Threads_lock so a thread waiting
3782 // on destroy_vm will wake up.
3783 if (number_of_non_daemon_threads() == 1)
3784 Threads_lock->notify_all();
3786 ThreadService::remove_thread(p, daemon);
3788 // Make sure that safepoint code disregard this thread. This is needed since
3789 // the thread might mess around with locks after this point. This can cause it
3790 // to do callbacks into the safepoint code. However, the safepoint code is not aware
3791 // of this thread since it is removed from the queue.
3792 p->set_terminated_value();
3793 } // unlock Threads_lock
3795 // Since Events::log uses a lock, we grab it outside the Threads_lock
3796 Events::log("Thread exited: " INTPTR_FORMAT, p);
3799 // Threads_lock must be held when this is called (or must be called during a safepoint)
3800 bool Threads::includes(JavaThread* p) {
3801 assert(Threads_lock->is_locked(), "sanity check");
3802 ALL_JAVA_THREADS(q) {
3810 // Operations on the Threads list for GC. These are not explicitly locked,
3811 // but the garbage collector must provide a safe context for them to run.
3812 // In particular, these things should never be called when the Threads_lock
3813 // is held by some other thread. (Note: the Safepoint abstraction also
3814 // uses the Threads_lock to gurantee this property. It also makes sure that
3815 // all threads gets blocked when exiting or starting).
3817 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3818 ALL_JAVA_THREADS(p) {
3821 VMThread::vm_thread()->oops_do(f, cf);
3824 void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
3825 // Introduce a mechanism allowing parallel threads to claim threads as
3826 // root groups. Overhead should be small enough to use all the time,
3827 // even in sequential code.
3828 SharedHeap* sh = SharedHeap::heap();
3829 bool is_par = (sh->n_par_threads() > 0);
3830 int cp = SharedHeap::heap()->strong_roots_parity();
3831 ALL_JAVA_THREADS(p) {
3832 if (p->claim_oops_do(is_par, cp)) {
3836 VMThread* vmt = VMThread::vm_thread();
3837 if (vmt->claim_oops_do(is_par, cp))
3838 vmt->oops_do(f, cf);
3842 // Used by ParallelScavenge
3843 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
3844 ALL_JAVA_THREADS(p) {
3845 q->enqueue(new ThreadRootsTask(p));
3847 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
3850 // Used by Parallel Old
3851 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
3852 ALL_JAVA_THREADS(p) {
3853 q->enqueue(new ThreadRootsMarkingTask(p));
3855 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
3859 void Threads::nmethods_do(CodeBlobClosure* cf) {
3860 ALL_JAVA_THREADS(p) {
3863 VMThread::vm_thread()->nmethods_do(cf);
3866 void Threads::gc_epilogue() {
3867 ALL_JAVA_THREADS(p) {
3872 void Threads::gc_prologue() {
3873 ALL_JAVA_THREADS(p) {
3878 void Threads::deoptimized_wrt_marked_nmethods() {
3879 ALL_JAVA_THREADS(p) {
3880 p->deoptimized_wrt_marked_nmethods();
3885 // Get count Java threads that are waiting to enter the specified monitor.
3886 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
3887 address monitor, bool doLock) {
3888 assert(doLock || SafepointSynchronize::is_at_safepoint(),
3889 "must grab Threads_lock or be at safepoint");
3890 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
3894 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3895 ALL_JAVA_THREADS(p) {
3896 if (p->is_Compiler_thread()) continue;
3898 address pending = (address)p->current_pending_monitor();
3899 if (pending == monitor) { // found a match
3900 if (i < count) result->append(p); // save the first count matches
3909 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) {
3911 Threads_lock->owned_by_self() ||
3912 SafepointSynchronize::is_at_safepoint(),
3913 "must grab Threads_lock or be at safepoint");
3915 // NULL owner means not locked so we can skip the search
3916 if (owner == NULL) return NULL;
3919 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3920 ALL_JAVA_THREADS(p) {
3921 // first, see if owner is the address of a Java thread
3922 if (owner == (address)p) return p;
3925 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled");
3926 if (UseHeavyMonitors) return NULL;
3929 // If we didn't find a matching Java thread and we didn't force use of
3930 // heavyweight monitors, then the owner is the stack address of the
3931 // Lock Word in the owning Java thread's stack.
3933 JavaThread* the_owner = NULL;
3935 MutexLockerEx ml(doLock ? Threads_lock : NULL);
3936 ALL_JAVA_THREADS(q) {
3937 if (q->is_lock_owned(owner)) {
3943 assert(the_owner != NULL, "Did not find owning Java thread for lock word address");
3947 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
3948 void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) {
3950 st->print_cr(os::local_time_string(buf, sizeof(buf)));
3952 st->print_cr("Full thread dump %s (%s %s):",
3953 Abstract_VM_Version::vm_name(),
3954 Abstract_VM_Version::vm_release(),
3955 Abstract_VM_Version::vm_info_string()
3960 // Dump concurrent locks
3961 ConcurrentLocksDump concurrent_locks;
3962 if (print_concurrent_locks) {
3963 concurrent_locks.dump_at_safepoint();
3967 ALL_JAVA_THREADS(p) {
3971 if (internal_format) {
3974 p->print_stack_on(st);
3979 if (print_concurrent_locks) {
3980 concurrent_locks.print_locks_on(p, st);
3985 VMThread::vm_thread()->print_on(st);
3987 Universe::heap()->print_gc_threads_on(st);
3988 WatcherThread* wt = WatcherThread::watcher_thread();
3989 if (wt != NULL) wt->print_on(st);
3991 CompileBroker::print_compiler_threads_on(st);
3995 // Threads::print_on_error() is called by fatal error handler. It's possible
3996 // that VM is not at safepoint and/or current thread is inside signal handler.
3997 // Don't print stack trace, as the stack may not be walkable. Don't allocate
3998 // memory (even in resource area), it might deadlock the error handler.
3999 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) {
4000 bool found_current = false;
4001 st->print_cr("Java Threads: ( => current thread )");
4002 ALL_JAVA_THREADS(thread) {
4003 bool is_current = (current == thread);
4004 found_current = found_current || is_current;
4006 st->print("%s", is_current ? "=>" : " ");
4008 st->print(PTR_FORMAT, thread);
4010 thread->print_on_error(st, buf, buflen);
4015 st->print_cr("Other Threads:");
4016 if (VMThread::vm_thread()) {
4017 bool is_current = (current == VMThread::vm_thread());
4018 found_current = found_current || is_current;
4019 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4021 st->print(PTR_FORMAT, VMThread::vm_thread());
4023 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4026 WatcherThread* wt = WatcherThread::watcher_thread();
4028 bool is_current = (current == wt);
4029 found_current = found_current || is_current;
4030 st->print("%s", is_current ? "=>" : " ");
4032 st->print(PTR_FORMAT, wt);
4034 wt->print_on_error(st, buf, buflen);
4037 if (!found_current) {
4039 st->print("=>" PTR_FORMAT " (exited) ", current);
4040 current->print_on_error(st, buf, buflen);
4045 // Internal SpinLock and Mutex
4046 // Based on ParkEvent
4048 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4050 // We employ SpinLocks _only for low-contention, fixed-length
4051 // short-duration critical sections where we're concerned
4052 // about native mutex_t or HotSpot Mutex:: latency.
4053 // The mux construct provides a spin-then-block mutual exclusion
4056 // Testing has shown that contention on the ListLock guarding gFreeList
4057 // is common. If we implement ListLock as a simple SpinLock it's common
4058 // for the JVM to devolve to yielding with little progress. This is true
4059 // despite the fact that the critical sections protected by ListLock are
4062 // TODO-FIXME: ListLock should be of type SpinLock.
4063 // We should make this a 1st-class type, integrated into the lock
4064 // hierarchy as leaf-locks. Critically, the SpinLock structure
4065 // should have sufficient padding to avoid false-sharing and excessive
4066 // cache-coherency traffic.
4069 typedef volatile int SpinLockT ;
4071 void Thread::SpinAcquire (volatile int * adr, const char * LockName) {
4072 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4073 return ; // normal fast-path return
4076 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4077 TEVENT (SpinAcquire - ctx) ;
4083 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4085 // Consider using a simple NakedSleep() instead.
4086 // Then SpinAcquire could be called by non-JVM threads
4087 Thread::current()->_ParkEvent->park(1) ;
4096 if (Atomic::cmpxchg (1, adr, 0) == 0) return ;
4100 void Thread::SpinRelease (volatile int * adr) {
4101 assert (*adr != 0, "invariant") ;
4102 OrderAccess::fence() ; // guarantee at least release consistency.
4103 // Roach-motel semantics.
4104 // It's safe if subsequent LDs and STs float "up" into the critical section,
4105 // but prior LDs and STs within the critical section can't be allowed
4106 // to reorder or float past the ST that releases the lock.
4110 // muxAcquire and muxRelease:
4112 // * muxAcquire and muxRelease support a single-word lock-word construct.
4113 // The LSB of the word is set IFF the lock is held.
4114 // The remainder of the word points to the head of a singly-linked list
4115 // of threads blocked on the lock.
4117 // * The current implementation of muxAcquire-muxRelease uses its own
4118 // dedicated Thread._MuxEvent instance. If we're interested in
4119 // minimizing the peak number of extant ParkEvent instances then
4120 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4121 // as certain invariants were satisfied. Specifically, care would need
4122 // to be taken with regards to consuming unpark() "permits".
4123 // A safe rule of thumb is that a thread would never call muxAcquire()
4124 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4125 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4126 // consume an unpark() permit intended for monitorenter, for instance.
4127 // One way around this would be to widen the restricted-range semaphore
4128 // implemented in park(). Another alternative would be to provide
4129 // multiple instances of the PlatformEvent() for each thread. One
4130 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4133 // -- Only as leaf locks
4134 // -- for short-term locking only as muxAcquire does not perform
4135 // thread state transitions.
4138 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4139 // but with parking or spin-then-park instead of pure spinning.
4140 // * Use Taura-Oyama-Yonenzawa locks.
4141 // * It's possible to construct a 1-0 lock if we encode the lockword as
4142 // (List,LockByte). Acquire will CAS the full lockword while Release
4143 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4144 // acquiring threads use timers (ParkTimed) to detect and recover from
4145 // the stranding window. Thread/Node structures must be aligned on 256-byte
4146 // boundaries by using placement-new.
4147 // * Augment MCS with advisory back-link fields maintained with CAS().
4148 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4149 // The validity of the backlinks must be ratified before we trust the value.
4150 // If the backlinks are invalid the exiting thread must back-track through the
4151 // the forward links, which are always trustworthy.
4152 // * Add a successor indication. The LockWord is currently encoded as
4153 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4154 // to provide the usual futile-wakeup optimization.
4155 // See RTStt for details.
4156 // * Consider schedctl.sc_nopreempt to cover the critical section.
4160 typedef volatile intptr_t MutexT ; // Mux Lock-word
4161 enum MuxBits { LOCKBIT = 1 } ;
4163 void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) {
4164 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4165 if (w == 0) return ;
4166 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4170 TEVENT (muxAcquire - Contention) ;
4171 ParkEvent * const Self = Thread::current()->_MuxEvent ;
4172 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ;
4174 int its = (os::is_MP() ? 100 : 0) + 1 ;
4176 // Optional spin phase: spin-then-park strategy
4177 while (--its >= 0) {
4179 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4185 Self->OnList = intptr_t(Lock) ;
4186 // The following fence() isn't _strictly necessary as the subsequent
4187 // CAS() both serializes execution and ratifies the fetched *Lock value.
4188 OrderAccess::fence();
4191 if ((w & LOCKBIT) == 0) {
4192 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4193 Self->OnList = 0 ; // hygiene - allows stronger asserts
4196 continue ; // Interference -- *Lock changed -- Just retry
4198 assert (w & LOCKBIT, "invariant") ;
4199 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4200 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ;
4203 while (Self->OnList != 0) {
4209 void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) {
4210 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ;
4211 if (w == 0) return ;
4212 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4216 TEVENT (muxAcquire - Contention) ;
4217 ParkEvent * ReleaseAfter = NULL ;
4219 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ;
4221 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ;
4223 guarantee (ev->OnList == 0, "invariant") ;
4224 int its = (os::is_MP() ? 100 : 0) + 1 ;
4226 // Optional spin phase: spin-then-park strategy
4227 while (--its >= 0) {
4229 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4230 if (ReleaseAfter != NULL) {
4231 ParkEvent::Release (ReleaseAfter) ;
4238 ev->OnList = intptr_t(Lock) ;
4239 // The following fence() isn't _strictly necessary as the subsequent
4240 // CAS() both serializes execution and ratifies the fetched *Lock value.
4241 OrderAccess::fence();
4244 if ((w & LOCKBIT) == 0) {
4245 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4247 // We call ::Release while holding the outer lock, thus
4248 // artificially lengthening the critical section.
4249 // Consider deferring the ::Release() until the subsequent unlock(),
4250 // after we've dropped the outer lock.
4251 if (ReleaseAfter != NULL) {
4252 ParkEvent::Release (ReleaseAfter) ;
4256 continue ; // Interference -- *Lock changed -- Just retry
4258 assert (w & LOCKBIT, "invariant") ;
4259 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT );
4260 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ;
4263 while (ev->OnList != 0) {
4269 // Release() must extract a successor from the list and then wake that thread.
4270 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4271 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4272 // Release() would :
4273 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4274 // (B) Extract a successor from the private list "in-hand"
4275 // (C) attempt to CAS() the residual back into *Lock over null.
4276 // If there were any newly arrived threads and the CAS() would fail.
4277 // In that case Release() would detach the RATs, re-merge the list in-hand
4278 // with the RATs and repeat as needed. Alternately, Release() might
4279 // detach and extract a successor, but then pass the residual list to the wakee.
4280 // The wakee would be responsible for reattaching and remerging before it
4281 // competed for the lock.
4283 // Both "pop" and DMR are immune from ABA corruption -- there can be
4284 // multiple concurrent pushers, but only one popper or detacher.
4285 // This implementation pops from the head of the list. This is unfair,
4286 // but tends to provide excellent throughput as hot threads remain hot.
4287 // (We wake recently run threads first).
4289 void Thread::muxRelease (volatile intptr_t * Lock) {
4291 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ;
4292 assert (w & LOCKBIT, "invariant") ;
4293 if (w == LOCKBIT) return ;
4294 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ;
4295 assert (List != NULL, "invariant") ;
4296 assert (List->OnList == intptr_t(Lock), "invariant") ;
4297 ParkEvent * nxt = List->ListNext ;
4299 // The following CAS() releases the lock and pops the head element.
4300 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4304 OrderAccess::fence() ;
4311 void Threads::verify() {
4312 ALL_JAVA_THREADS(p) {
4315 VMThread* thread = VMThread::vm_thread();
4316 if (thread != NULL) thread->verify();