jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp@f90c822e73f8 (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp@f90c822e73f8 (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp

Wed, 27 Apr 2016 01:25:04 +0800

author: aoqi
date: Wed, 27 Apr 2016 01:25:04 +0800
changeset 0: f90c822e73f8
child 6876: 710a3c8b516e
permissions: -rw-r--r--

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http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/
changeset: 6782:28b50d07f6f8
tag: jdk8u25-b17

 /*
  * Copyright (c) 2001, 2014, 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.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp"
 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
 #include "memory/genCollectedHeap.hpp"
 #include "oops/instanceRefKlass.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/init.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/java.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/os.hpp"
 #include "runtime/vmThread.hpp"
 // ======= Concurrent Mark Sweep Thread ========
 // The CMS thread is created when Concurrent Mark Sweep is used in the
 // older of two generations in a generational memory system.
 ConcurrentMarkSweepThread*
      ConcurrentMarkSweepThread::_cmst     = NULL;
 CMSCollector* ConcurrentMarkSweepThread::_collector = NULL;
 bool ConcurrentMarkSweepThread::_should_terminate = false;
 int  ConcurrentMarkSweepThread::_CMS_flag         = CMS_nil;
 volatile jint ConcurrentMarkSweepThread::_pending_yields      = 0;
 volatile jint ConcurrentMarkSweepThread::_pending_decrements  = 0;
 volatile jint ConcurrentMarkSweepThread::_icms_disabled   = 0;
 volatile bool ConcurrentMarkSweepThread::_should_run     = false;
 // When icms is enabled, the icms thread is stopped until explicitly
 // started.
 volatile bool ConcurrentMarkSweepThread::_should_stop    = true;
 SurrogateLockerThread*
      ConcurrentMarkSweepThread::_slt = NULL;
 SurrogateLockerThread::SLT_msg_type
      ConcurrentMarkSweepThread::_sltBuffer = SurrogateLockerThread::empty;
 Monitor*
      ConcurrentMarkSweepThread::_sltMonitor = NULL;
 ConcurrentMarkSweepThread::ConcurrentMarkSweepThread(CMSCollector* collector)
   : ConcurrentGCThread() {
   assert(UseConcMarkSweepGC,  "UseConcMarkSweepGC should be set");
   assert(_cmst == NULL, "CMS thread already created");
   _cmst = this;
   assert(_collector == NULL, "Collector already set");
   _collector = collector;
   set_name("Concurrent Mark-Sweep GC Thread");
   if (os::create_thread(this, os::cgc_thread)) {
     // An old comment here said: "Priority should be just less
     // than that of VMThread".  Since the VMThread runs at
     // NearMaxPriority, the old comment was inaccurate, but
     // changing the default priority to NearMaxPriority-1
     // could change current behavior, so the default of
     // NearMaxPriority stays in place.
     //
     // Note that there's a possibility of the VMThread
     // starving if UseCriticalCMSThreadPriority is on.
     // That won't happen on Solaris for various reasons,
     // but may well happen on non-Solaris platforms.
     int native_prio;
     if (UseCriticalCMSThreadPriority) {
       native_prio = os::java_to_os_priority[CriticalPriority];
     } else {
       native_prio = os::java_to_os_priority[NearMaxPriority];
     }
     os::set_native_priority(this, native_prio);
     if (!DisableStartThread) {
       os::start_thread(this);
     }
   }
   _sltMonitor = SLT_lock;
   assert(!CMSIncrementalMode || icms_is_enabled(), "Error");
 }
 void ConcurrentMarkSweepThread::run() {
   assert(this == cmst(), "just checking");
   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");
   if (BindCMSThreadToCPU && !os::bind_to_processor(CPUForCMSThread)) {
     warning("Couldn't bind CMS thread to processor " UINTX_FORMAT, CPUForCMSThread);
   }
   // Wait until Universe::is_fully_initialized()
   {
     CMSLoopCountWarn loopX("CMS::run", "waiting for "
                            "Universe::is_fully_initialized()", 2);
     MutexLockerEx x(CGC_lock, true);
     set_CMS_flag(CMS_cms_wants_token);
     // Wait until Universe is initialized and all initialization is completed.
     while (!is_init_completed() && !Universe::is_fully_initialized() &&
            !_should_terminate) {
       CGC_lock->wait(true, 200);
       loopX.tick();
     }
     // Wait until the surrogate locker thread that will do
     // pending list locking on our behalf has been created.
     // We cannot start the SLT thread ourselves since we need
     // to be a JavaThread to do so.
     CMSLoopCountWarn loopY("CMS::run", "waiting for SLT installation", 2);
     while (_slt == NULL && !_should_terminate) {
       CGC_lock->wait(true, 200);
       loopY.tick();
     }
     clear_CMS_flag(CMS_cms_wants_token);
   }
   while (!_should_terminate) {
     sleepBeforeNextCycle();
     if (_should_terminate) break;
     GCCause::Cause cause = _collector->_full_gc_requested ?
       _collector->_full_gc_cause : GCCause::_cms_concurrent_mark;
     _collector->collect_in_background(false, cause);
   }
   assert(_should_terminate, "just checking");
   // Check that the state of any protocol for synchronization
   // between background (CMS) and foreground collector is "clean"
   // (i.e. will not potentially block the foreground collector,
   // requiring action by us).
   verify_ok_to_terminate();
   // Signal that it is terminated
   {
     MutexLockerEx mu(Terminator_lock,
                      Mutex::_no_safepoint_check_flag);
     assert(_cmst == this, "Weird!");
     _cmst = NULL;
     Terminator_lock->notify();
   }
   // Thread destructor usually does this..
   ThreadLocalStorage::set_thread(NULL);
 }
 #ifndef PRODUCT
 void ConcurrentMarkSweepThread::verify_ok_to_terminate() const {
   assert(!(CGC_lock->owned_by_self() || cms_thread_has_cms_token() ||
            cms_thread_wants_cms_token()),
          "Must renounce all worldly possessions and desires for nirvana");
   _collector->verify_ok_to_terminate();
 }
 #endif
 // create and start a new ConcurrentMarkSweep Thread for given CMS generation
 ConcurrentMarkSweepThread* ConcurrentMarkSweepThread::start(CMSCollector* collector) {
   if (!_should_terminate) {
     assert(cmst() == NULL, "start() called twice?");
     ConcurrentMarkSweepThread* th = new ConcurrentMarkSweepThread(collector);
     assert(cmst() == th, "Where did the just-created CMS thread go?");
     return th;
   }
   return NULL;
 }
 void ConcurrentMarkSweepThread::stop() {
   if (CMSIncrementalMode) {
     // Disable incremental mode and wake up the thread so it notices the change.
     disable_icms();
     start_icms();
   }
   // it is ok to take late safepoints here, if needed
   {
     MutexLockerEx x(Terminator_lock);
     _should_terminate = true;
   }
   { // Now post a notify on CGC_lock so as to nudge
     // CMS thread(s) that might be slumbering in
     // sleepBeforeNextCycle.
     MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
     CGC_lock->notify_all();
   }
   { // Now wait until (all) CMS thread(s) have exited
     MutexLockerEx x(Terminator_lock);
     while(cmst() != NULL) {
       Terminator_lock->wait();
     }
   }
 }
 void ConcurrentMarkSweepThread::threads_do(ThreadClosure* tc) {
   assert(tc != NULL, "Null ThreadClosure");
   if (_cmst != NULL) {
     tc->do_thread(_cmst);
   }
   assert(Universe::is_fully_initialized(),
          "Called too early, make sure heap is fully initialized");
   if (_collector != NULL) {
     AbstractWorkGang* gang = _collector->conc_workers();
     if (gang != NULL) {
       gang->threads_do(tc);
     }
   }
 }
 void ConcurrentMarkSweepThread::print_on(outputStream* st) const {
   st->print("\"%s\" ", name());
   Thread::print_on(st);
   st->cr();
 }
 void ConcurrentMarkSweepThread::print_all_on(outputStream* st) {
   if (_cmst != NULL) {
     _cmst->print_on(st);
     st->cr();
   }
   if (_collector != NULL) {
     AbstractWorkGang* gang = _collector->conc_workers();
     if (gang != NULL) {
       gang->print_worker_threads_on(st);
     }
   }
 }
 void ConcurrentMarkSweepThread::synchronize(bool is_cms_thread) {
   assert(UseConcMarkSweepGC, "just checking");
   MutexLockerEx x(CGC_lock,
                   Mutex::_no_safepoint_check_flag);
   if (!is_cms_thread) {
     assert(Thread::current()->is_VM_thread(), "Not a VM thread");
     CMSSynchronousYieldRequest yr;
     while (CMS_flag_is_set(CMS_cms_has_token)) {
       // indicate that we want to get the token
       set_CMS_flag(CMS_vm_wants_token);
       CGC_lock->wait(true);
     }
     // claim the token and proceed
     clear_CMS_flag(CMS_vm_wants_token);
     set_CMS_flag(CMS_vm_has_token);
   } else {
     assert(Thread::current()->is_ConcurrentGC_thread(),
            "Not a CMS thread");
     // The following barrier assumes there's only one CMS thread.
     // This will need to be modified is there are more CMS threads than one.
     while (CMS_flag_is_set(CMS_vm_has_token | CMS_vm_wants_token)) {
       set_CMS_flag(CMS_cms_wants_token);
       CGC_lock->wait(true);
     }
     // claim the token
     clear_CMS_flag(CMS_cms_wants_token);
     set_CMS_flag(CMS_cms_has_token);
   }
 }
 void ConcurrentMarkSweepThread::desynchronize(bool is_cms_thread) {
   assert(UseConcMarkSweepGC, "just checking");
   MutexLockerEx x(CGC_lock,
                   Mutex::_no_safepoint_check_flag);
   if (!is_cms_thread) {
     assert(Thread::current()->is_VM_thread(), "Not a VM thread");
     assert(CMS_flag_is_set(CMS_vm_has_token), "just checking");
     clear_CMS_flag(CMS_vm_has_token);
     if (CMS_flag_is_set(CMS_cms_wants_token)) {
       // wake-up a waiting CMS thread
       CGC_lock->notify();
     }
     assert(!CMS_flag_is_set(CMS_vm_has_token | CMS_vm_wants_token),
            "Should have been cleared");
   } else {
     assert(Thread::current()->is_ConcurrentGC_thread(),
            "Not a CMS thread");
     assert(CMS_flag_is_set(CMS_cms_has_token), "just checking");
     clear_CMS_flag(CMS_cms_has_token);
     if (CMS_flag_is_set(CMS_vm_wants_token)) {
       // wake-up a waiting VM thread
       CGC_lock->notify();
     }
     assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
            "Should have been cleared");
   }
 }
 // Wait until any cms_lock event
 void ConcurrentMarkSweepThread::wait_on_cms_lock(long t_millis) {
   MutexLockerEx x(CGC_lock,
                   Mutex::_no_safepoint_check_flag);
   if (_should_terminate || _collector->_full_gc_requested) {
     return;
   }
   set_CMS_flag(CMS_cms_wants_token);   // to provoke notifies
   CGC_lock->wait(Mutex::_no_safepoint_check_flag, t_millis);
   clear_CMS_flag(CMS_cms_wants_token);
   assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
          "Should not be set");
 }
 // Wait until the next synchronous GC, a concurrent full gc request,
 // or a timeout, whichever is earlier.
 void ConcurrentMarkSweepThread::wait_on_cms_lock_for_scavenge(long t_millis) {
   // Wait time in millis or 0 value representing infinite wait for a scavenge
   assert(t_millis >= 0, "Wait time for scavenge should be 0 or positive");
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   double start_time_secs = os::elapsedTime();
   double end_time_secs = start_time_secs + (t_millis / ((double) MILLIUNITS));
   // Total collections count before waiting loop
   unsigned int before_count;
   {
     MutexLockerEx hl(Heap_lock, Mutex::_no_safepoint_check_flag);
     before_count = gch->total_collections();
   }
   unsigned int loop_count = 0;
   while(!_should_terminate) {
     double now_time = os::elapsedTime();
     long wait_time_millis;
     if(t_millis != 0) {
       // New wait limit
       wait_time_millis = (long) ((end_time_secs - now_time) * MILLIUNITS);
       if(wait_time_millis <= 0) {
         // Wait time is over
         break;
       }
     } else {
       // No wait limit, wait if necessary forever
       wait_time_millis = 0;
     }
     // Wait until the next event or the remaining timeout
     {
       MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
       if (_should_terminate || _collector->_full_gc_requested) {
         return;
       }
       set_CMS_flag(CMS_cms_wants_token);   // to provoke notifies
       assert(t_millis == 0 || wait_time_millis > 0, "Sanity");
       CGC_lock->wait(Mutex::_no_safepoint_check_flag, wait_time_millis);
       clear_CMS_flag(CMS_cms_wants_token);
       assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token),
              "Should not be set");
     }
     // Extra wait time check before entering the heap lock to get the collection count
     if(t_millis != 0 && os::elapsedTime() >= end_time_secs) {
       // Wait time is over
       break;
     }
     // Total collections count after the event
     unsigned int after_count;
     {
       MutexLockerEx hl(Heap_lock, Mutex::_no_safepoint_check_flag);
       after_count = gch->total_collections();
     }
     if(before_count != after_count) {
       // There was a collection - success
       break;
     }
     // Too many loops warning
     if(++loop_count == 0) {
       warning("wait_on_cms_lock_for_scavenge() has looped %u times", loop_count - 1);
     }
   }
 }
 void ConcurrentMarkSweepThread::sleepBeforeNextCycle() {
   while (!_should_terminate) {
     if (CMSIncrementalMode) {
       icms_wait();
       if(CMSWaitDuration >= 0) {
         // Wait until the next synchronous GC, a concurrent full gc
         // request or a timeout, whichever is earlier.
         wait_on_cms_lock_for_scavenge(CMSWaitDuration);
       }
       return;
     } else {
       if(CMSWaitDuration >= 0) {
         // Wait until the next synchronous GC, a concurrent full gc
         // request or a timeout, whichever is earlier.
         wait_on_cms_lock_for_scavenge(CMSWaitDuration);
       } else {
         // Wait until any cms_lock event or check interval not to call shouldConcurrentCollect permanently
         wait_on_cms_lock(CMSCheckInterval);
       }
     }
     // Check if we should start a CMS collection cycle
     if (_collector->shouldConcurrentCollect()) {
       return;
     }
     // .. collection criterion not yet met, let's go back
     // and wait some more
   }
 }
 // Incremental CMS
 void ConcurrentMarkSweepThread::start_icms() {
   assert(UseConcMarkSweepGC && CMSIncrementalMode, "just checking");
   MutexLockerEx x(iCMS_lock, Mutex::_no_safepoint_check_flag);
   trace_state("start_icms");
   _should_run = true;
   iCMS_lock->notify_all();
 }
 void ConcurrentMarkSweepThread::stop_icms() {
   assert(UseConcMarkSweepGC && CMSIncrementalMode, "just checking");
   MutexLockerEx x(iCMS_lock, Mutex::_no_safepoint_check_flag);
   if (!_should_stop) {
     trace_state("stop_icms");
     _should_stop = true;
     _should_run = false;
     asynchronous_yield_request();
     iCMS_lock->notify_all();
   }
 }
 void ConcurrentMarkSweepThread::icms_wait() {
   assert(UseConcMarkSweepGC && CMSIncrementalMode, "just checking");
   if (_should_stop && icms_is_enabled()) {
     MutexLockerEx x(iCMS_lock, Mutex::_no_safepoint_check_flag);
     trace_state("pause_icms");
     _collector->stats().stop_cms_timer();
     while(!_should_run && icms_is_enabled()) {
       iCMS_lock->wait(Mutex::_no_safepoint_check_flag);
     }
     _collector->stats().start_cms_timer();
     _should_stop = false;
     trace_state("pause_icms end");
   }
 }
 // Note: this method, although exported by the ConcurrentMarkSweepThread,
 // which is a non-JavaThread, can only be called by a JavaThread.
 // Currently this is done at vm creation time (post-vm-init) by the
 // main/Primordial (Java)Thread.
 // XXX Consider changing this in the future to allow the CMS thread
 // itself to create this thread?
 void ConcurrentMarkSweepThread::makeSurrogateLockerThread(TRAPS) {
   assert(UseConcMarkSweepGC, "SLT thread needed only for CMS GC");
   assert(_slt == NULL, "SLT already created");
   _slt = SurrogateLockerThread::make(THREAD);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp@f90c822e73f8 (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp