jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/shared/concurrentGCThread.cpp@6e0aac35bfa9 (annotated)

src/share/vm/gc_implementation/shared/concurrentGCThread.cpp@6e0aac35bfa9 (annotated)

src/share/vm/gc_implementation/shared/concurrentGCThread.cpp

Fri, 01 Oct 2010 16:43:05 -0400

author: tonyp
date: Fri, 01 Oct 2010 16:43:05 -0400
changeset 2197: 6e0aac35bfa9
parent 1907: c18cbe5936b8
child 2314: f95d63e2154a
permissions: -rw-r--r--

6980838: G1: guarantee(false) failed: thread has an unexpected active value in its SATB queue
Summary: Under certain circumstances a safepoint could happen between a JavaThread object being created and that object being added to the Java threads list. This could cause the active field of that thread's SATB queue to get out-of-sync with respect to the other Java threads. The solution is to activate the SATB queue, when necessary, before adding the thread to the Java threads list, not when the JavaThread object is created. The changeset also includes a small fix to rename the surrogate locker thread from "Surrogate Locker Thread (CMS)" to "Surrogate Locker Thread (Concurrent GC)" since it's also used in G1.
Reviewed-by: iveresov, ysr, johnc, jcoomes

 /*
  * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 // CopyrightVersion 1.2
 # include "incls/_precompiled.incl"
 # include "incls/_concurrentGCThread.cpp.incl"
 int  ConcurrentGCThread::_CGC_flag            = CGC_nil;
 SuspendibleThreadSet ConcurrentGCThread::_sts;
 ConcurrentGCThread::ConcurrentGCThread() :
   _should_terminate(false), _has_terminated(false) {
   _sts.initialize();
 };
 void ConcurrentGCThread::stopWorldAndDo(VoidClosure* op) {
   MutexLockerEx x(Heap_lock,
                   Mutex::_no_safepoint_check_flag);
   // warning("CGC: about to try stopping world");
   SafepointSynchronize::begin();
   // warning("CGC: successfully stopped world");
   op->do_void();
   SafepointSynchronize::end();
   // warning("CGC: successfully restarted world");
 }
 void ConcurrentGCThread::safepoint_synchronize() {
   _sts.suspend_all();
 }
 void ConcurrentGCThread::safepoint_desynchronize() {
   _sts.resume_all();
 }
 void ConcurrentGCThread::create_and_start() {
   if (os::create_thread(this, os::cgc_thread)) {
     // XXX: need to set this to low priority
     // unless "agressive mode" set; priority
     // should be just less than that of VMThread.
     os::set_priority(this, NearMaxPriority);
     if (!_should_terminate && !DisableStartThread) {
       os::start_thread(this);
     }
   }
 }
 void ConcurrentGCThread::initialize_in_thread() {
   this->record_stack_base_and_size();
   this->initialize_thread_local_storage();
   this->set_active_handles(JNIHandleBlock::allocate_block());
   // From this time Thread::current() should be working.
   assert(this == Thread::current(), "just checking");
 }
 void ConcurrentGCThread::wait_for_universe_init() {
   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
   while (!is_init_completed() && !_should_terminate) {
     CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
   }
 }
 void ConcurrentGCThread::terminate() {
   // Signal that it is terminated
   {
     MutexLockerEx mu(Terminator_lock,
                      Mutex::_no_safepoint_check_flag);
     _has_terminated = true;
     Terminator_lock->notify();
   }
   // Thread destructor usually does this..
   ThreadLocalStorage::set_thread(NULL);
 }
 void SuspendibleThreadSet::initialize_work() {
   MutexLocker x(STS_init_lock);
   if (!_initialized) {
     _m             = new Monitor(Mutex::leaf,
                                  "SuspendibleThreadSetLock", true);
     _async         = 0;
     _async_stop    = false;
     _async_stopped = 0;
     _initialized   = true;
   }
 }
 void SuspendibleThreadSet::join() {
   initialize();
   MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
   while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
   _async++;
   assert(_async > 0, "Huh.");
 }
 void SuspendibleThreadSet::leave() {
   assert(_initialized, "Must be initialized.");
   MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
   _async--;
   assert(_async >= 0, "Huh.");
   if (_async_stop) _m->notify_all();
 }
 void SuspendibleThreadSet::yield(const char* id) {
   assert(_initialized, "Must be initialized.");
   if (_async_stop) {
     MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
     if (_async_stop) {
       _async_stopped++;
       assert(_async_stopped > 0, "Huh.");
       if (_async_stopped == _async) {
         if (ConcGCYieldTimeout > 0) {
           double now = os::elapsedTime();
           guarantee((now - _suspend_all_start) * 1000.0 <
                     (double)ConcGCYieldTimeout,
                     "Long delay; whodunit?");
         }
       }
       _m->notify_all();
       while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
       _async_stopped--;
       assert(_async >= 0, "Huh");
       _m->notify_all();
     }
   }
 }
 void SuspendibleThreadSet::suspend_all() {
   initialize();  // If necessary.
   if (ConcGCYieldTimeout > 0) {
     _suspend_all_start = os::elapsedTime();
   }
   MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
   assert(!_async_stop, "Only one at a time.");
   _async_stop = true;
   while (_async_stopped < _async) _m->wait(Mutex::_no_safepoint_check_flag);
 }
 void SuspendibleThreadSet::resume_all() {
   assert(_initialized, "Must be initialized.");
   MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
   assert(_async_stopped == _async, "Huh.");
   _async_stop = false;
   _m->notify_all();
 }
 static void _sltLoop(JavaThread* thread, TRAPS) {
   SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
   slt->loop();
 }
 SurrogateLockerThread::SurrogateLockerThread() :
   JavaThread(&_sltLoop),
   _monitor(Mutex::nonleaf, "SLTMonitor"),
   _buffer(empty)
 {}
 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
   klassOop k =
     SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(),
                                       true, CHECK_NULL);
   instanceKlassHandle klass (THREAD, k);
   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
   const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)";
   Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
   // Initialize thread_oop to put it into the system threadGroup
   Handle thread_group (THREAD, Universe::system_thread_group());
   JavaValue result(T_VOID);
   JavaCalls::call_special(&result, thread_oop,
                           klass,
                           vmSymbolHandles::object_initializer_name(),
                           vmSymbolHandles::threadgroup_string_void_signature(),
                           thread_group,
                           string,
                           CHECK_NULL);
   SurrogateLockerThread* res;
   {
     MutexLocker mu(Threads_lock);
     res = new SurrogateLockerThread();
     // At this point it may be possible that no osthread was created for the
     // JavaThread due to lack of memory. We would have to throw an exception
     // in that case. However, since this must work and we do not allow
     // exceptions anyway, check and abort if this fails.
     if (res == NULL || res->osthread() == NULL) {
       vm_exit_during_initialization("java.lang.OutOfMemoryError",
                                     "unable to create new native thread");
     }
     java_lang_Thread::set_thread(thread_oop(), res);
     java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
     java_lang_Thread::set_daemon(thread_oop());
     res->set_threadObj(thread_oop());
     Threads::add(res);
     Thread::start(res);
   }
   os::yield(); // This seems to help with initial start-up of SLT
   return res;
 }
 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
   MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
   assert(_buffer == empty, "Should be empty");
   assert(msg != empty, "empty message");
   _buffer = msg;
   while (_buffer != empty) {
     _monitor.notify();
     _monitor.wait(Mutex::_no_safepoint_check_flag);
   }
 }
 // ======= Surrogate Locker Thread =============
 void SurrogateLockerThread::loop() {
   BasicLock pll_basic_lock;
   SLT_msg_type msg;
   debug_only(unsigned int owned = 0;)
   while (/* !isTerminated() */ 1) {
     {
       MutexLocker x(&_monitor);
       // Since we are a JavaThread, we can't be here at a safepoint.
       assert(!SafepointSynchronize::is_at_safepoint(),
              "SLT is a JavaThread");
       // wait for msg buffer to become non-empty
       while (_buffer == empty) {
         _monitor.notify();
         _monitor.wait();
       }
       msg = _buffer;
     }
     switch(msg) {
       case acquirePLL: {
         instanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
         debug_only(owned++;)
         break;
       }
       case releaseAndNotifyPLL: {
         assert(owned > 0, "Don't have PLL");
         instanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
         debug_only(owned--;)
         break;
       }
       case empty:
       default: {
         guarantee(false,"Unexpected message in _buffer");
         break;
       }
     }
     {
       MutexLocker x(&_monitor);
       // Since we are a JavaThread, we can't be here at a safepoint.
       assert(!SafepointSynchronize::is_at_safepoint(),
              "SLT is a JavaThread");
       _buffer = empty;
       _monitor.notify();
     }
   }
   assert(!_monitor.owned_by_self(), "Should unlock before exit.");
 }
 // ===== STS Access From Outside CGCT =====
 void ConcurrentGCThread::stsYield(const char* id) {
   assert( Thread::current()->is_ConcurrentGC_thread(),
           "only a conc GC thread can call this" );
   _sts.yield(id);
 }
 bool ConcurrentGCThread::stsShouldYield() {
   assert( Thread::current()->is_ConcurrentGC_thread(),
           "only a conc GC thread can call this" );
   return _sts.should_yield();
 }
 void ConcurrentGCThread::stsJoin() {
   assert( Thread::current()->is_ConcurrentGC_thread(),
           "only a conc GC thread can call this" );
   _sts.join();
 }
 void ConcurrentGCThread::stsLeave() {
   assert( Thread::current()->is_ConcurrentGC_thread(),
           "only a conc GC thread can call this" );
   _sts.leave();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/shared/concurrentGCThread.cpp@6e0aac35bfa9 (annotated)

src/share/vm/gc_implementation/shared/concurrentGCThread.cpp