changeset 30205:0bff2f15867f

8075214: SIGSEGV in nmethod sweeping Summary: Changed implementation of forceNMethodSweep() to request sweep from existing sweeper thread. Reviewed-by: kvn, mgerdin, dholmes
author thartmann
date Mon, 30 Mar 2015 07:54:23 +0200
parents 4f690700bbb9
children 7bf1f70e147b
files hotspot/src/share/vm/prims/whitebox.cpp hotspot/src/share/vm/prims/whitebox.hpp hotspot/src/share/vm/runtime/sweeper.cpp hotspot/src/share/vm/runtime/sweeper.hpp
diffstat 4 files changed, 37 insertions(+), 46 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/src/share/vm/prims/whitebox.cpp	Fri Mar 27 15:08:13 2015 +0000
+++ b/hotspot/src/share/vm/prims/whitebox.cpp	Mon Mar 30 07:54:23 2015 +0200
@@ -819,46 +819,9 @@
   mo.notify_all();
 WB_END
 
-void WhiteBox::sweeper_thread_entry(JavaThread* thread, TRAPS) {
-  guarantee(WhiteBoxAPI, "internal testing API :: WhiteBox has to be enabled");
-  {
-    MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
-    NMethodSweeper::_should_sweep = true;
-  }
-  NMethodSweeper::possibly_sweep();
-}
-
-JavaThread* WhiteBox::create_sweeper_thread(TRAPS) {
-  // create sweeper thread w/ custom entry -- one iteration instead of loop
-  CodeCacheSweeperThread* sweeper_thread = new CodeCacheSweeperThread();
-  sweeper_thread->set_entry_point(&WhiteBox::sweeper_thread_entry);
-
-  // create j.l.Thread object and associate it w/ sweeper thread
-  {
-    // inherit deamon property from current thread
-    bool is_daemon = java_lang_Thread::is_daemon(JavaThread::current()->threadObj());
-
-    HandleMark hm(THREAD);
-    Handle thread_group(THREAD, Universe::system_thread_group());
-    const char* name = "WB Sweeper thread";
-    sweeper_thread->allocate_threadObj(thread_group, name, is_daemon, THREAD);
-  }
-
-  {
-    MutexLocker mu(Threads_lock, THREAD);
-    Threads::add(sweeper_thread);
-  }
-  return sweeper_thread;
-}
-
-WB_ENTRY(jobject, WB_ForceNMethodSweep(JNIEnv* env, jobject o))
-  JavaThread* sweeper_thread = WhiteBox::create_sweeper_thread(Thread::current());
-  if (sweeper_thread == NULL) {
-    return NULL;
-  }
-  jobject result = JNIHandles::make_local(env, sweeper_thread->threadObj());
-  Thread::start(sweeper_thread);
-  return result;
+WB_ENTRY(void, WB_ForceNMethodSweep(JNIEnv* env, jobject o))
+  // Force a code cache sweep and block until it finished
+  NMethodSweeper::force_sweep();
 WB_END
 
 WB_ENTRY(jboolean, WB_IsInStringTable(JNIEnv* env, jobject o, jstring javaString))
@@ -1402,7 +1365,7 @@
   {CC"getCPUFeatures",     CC"()Ljava/lang/String;",  (void*)&WB_GetCPUFeatures     },
   {CC"getNMethod",         CC"(Ljava/lang/reflect/Executable;Z)[Ljava/lang/Object;",
                                                       (void*)&WB_GetNMethod         },
-  {CC"forceNMethodSweep0", CC"()Ljava/lang/Thread;",  (void*)&WB_ForceNMethodSweep  },
+  {CC"forceNMethodSweep",  CC"()V",                   (void*)&WB_ForceNMethodSweep  },
   {CC"allocateCodeBlob",   CC"(II)J",                 (void*)&WB_AllocateCodeBlob   },
   {CC"freeCodeBlob",       CC"(J)V",                  (void*)&WB_FreeCodeBlob       },
   {CC"getCodeHeapEntries", CC"(I)[Ljava/lang/Object;",(void*)&WB_GetCodeHeapEntries },
--- a/hotspot/src/share/vm/prims/whitebox.hpp	Fri Mar 27 15:08:13 2015 +0000
+++ b/hotspot/src/share/vm/prims/whitebox.hpp	Mon Mar 30 07:54:23 2015 +0200
@@ -70,8 +70,6 @@
     Symbol* signature_symbol);
   static const char* lookup_jstring(const char* field_name, oop object);
   static bool lookup_bool(const char* field_name, oop object);
-  static void sweeper_thread_entry(JavaThread* thread, TRAPS);
-  static JavaThread* create_sweeper_thread(TRAPS);
   static int get_blob_type(const CodeBlob* code);
   static CodeHeap* get_code_heap(int blob_type);
   static CodeBlob* allocate_code_blob(int size, int blob_type);
--- a/hotspot/src/share/vm/runtime/sweeper.cpp	Fri Mar 27 15:08:13 2015 +0000
+++ b/hotspot/src/share/vm/runtime/sweeper.cpp	Mon Mar 30 07:54:23 2015 +0200
@@ -144,6 +144,7 @@
 int      NMethodSweeper::_seen                         = 0;    // Nof. nmethod we have currently processed in current pass of CodeCache
 
 volatile bool NMethodSweeper::_should_sweep            = true; // Indicates if we should invoke the sweeper
+volatile bool NMethodSweeper::_force_sweep             = false;// Indicates if we should force a sweep
 volatile int  NMethodSweeper::_bytes_changed           = 0;    // Counts the total nmethod size if the nmethod changed from:
                                                                //   1) alive       -> not_entrant
                                                                //   2) not_entrant -> zombie
@@ -276,6 +277,23 @@
 }
 
 /**
+  * Wakes up the sweeper thread and forces a sweep. Blocks until it finished.
+  */
+void NMethodSweeper::force_sweep() {
+  ThreadBlockInVM tbivm(JavaThread::current());
+  MutexLockerEx waiter(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+  // Request forced sweep
+  _force_sweep = true;
+  while (_force_sweep) {
+    // Notify sweeper that we want to force a sweep and wait for completion.
+    // In case a sweep currently takes place we timeout and try again because
+    // we want to enforce a full sweep.
+    CodeCache_lock->notify();
+    CodeCache_lock->wait(Mutex::_no_safepoint_check_flag, 1000);
+  }
+}
+
+/**
  * Handle a safepoint request
  */
 void NMethodSweeper::handle_safepoint_request() {
@@ -335,6 +353,9 @@
     }
   }
 
+  // Remember if this was a forced sweep
+  bool forced = _force_sweep;
+
   // Force stack scanning if there is only 10% free space in the code cache.
   // We force stack scanning only non-profiled code heap gets full, since critical
   // allocation go to the non-profiled heap and we must be make sure that there is
@@ -344,7 +365,7 @@
     do_stack_scanning();
   }
 
-  if (_should_sweep) {
+  if (_should_sweep || forced) {
     init_sweeper_log();
     sweep_code_cache();
   }
@@ -356,12 +377,20 @@
   _should_sweep = false;
   // If there was enough state change, 'possibly_enable_sweeper()'
   // sets '_should_sweep' to true
-   possibly_enable_sweeper();
+  possibly_enable_sweeper();
   // Reset _bytes_changed only if there was enough state change. _bytes_changed
   // can further increase by calls to 'report_state_change'.
   if (_should_sweep) {
     _bytes_changed = 0;
   }
+
+  if (forced) {
+    // Notify requester that forced sweep finished
+    assert(_force_sweep, "Should be a forced sweep");
+    MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+    _force_sweep = false;
+    CodeCache_lock->notify();
+  }
 }
 
 void NMethodSweeper::sweep_code_cache() {
--- a/hotspot/src/share/vm/runtime/sweeper.hpp	Fri Mar 27 15:08:13 2015 +0000
+++ b/hotspot/src/share/vm/runtime/sweeper.hpp	Mon Mar 30 07:54:23 2015 +0200
@@ -54,7 +54,6 @@
 //     nmethod's space is freed.
 
 class NMethodSweeper : public AllStatic {
-  friend class WhiteBox;
  private:
   enum MethodStateChange {
     None,
@@ -71,6 +70,7 @@
 
   static volatile int  _sweep_started;            // Flag to control conc sweeper
   static volatile bool _should_sweep;             // Indicates if we should invoke the sweeper
+  static volatile bool _force_sweep;              // Indicates if we should force a sweep
   static volatile int _bytes_changed;             // Counts the total nmethod size if the nmethod changed from:
                                                   //   1) alive       -> not_entrant
                                                   //   2) not_entrant -> zombie
@@ -117,6 +117,7 @@
   static void mark_active_nmethods();      // Invoked at the end of each safepoint
   static void sweeper_loop();
   static void notify(int code_blob_type);  // Possibly start the sweeper thread.
+  static void force_sweep();
 
   static int hotness_counter_reset_val();
   static void report_state_change(nmethod* nm);