| /* |
| * Copyright (c) 2001, 2015, 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/cms/concurrentMarkSweepGeneration.inline.hpp" |
| #include "gc/cms/concurrentMarkSweepThread.hpp" |
| #include "gc/shared/gcId.hpp" |
| #include "gc/shared/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 ======== |
| |
| 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; |
| |
| 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("CMS Main 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; |
| } |
| |
| void ConcurrentMarkSweepThread::run() { |
| assert(this == cmst(), "just checking"); |
| |
| initialize_in_thread(); |
| // 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; |
| GCIdMark gc_id_mark; |
| GCCause::Cause cause = _collector->_full_gc_requested ? |
| _collector->_full_gc_cause : GCCause::_cms_concurrent_mark; |
| _collector->collect_in_background(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(); |
| } |
| } |
| |
| #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() { |
| // 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_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(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 |
| } |
| } |
| |
| // 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); |
| } |