author | tonyp |
Mon, 28 Jun 2010 14:13:17 -0400 | |
changeset 6058 | 9c9aec6ab47d |
parent 5547 | f4b087cbb361 |
child 7397 | 5b173b4ca846 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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* |
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*/ |
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# include "incls/_precompiled.incl" |
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# include "incls/_vmCMSOperations.cpp.incl" |
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HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__begin); |
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HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__end); |
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HS_DTRACE_PROBE_DECL(hs_private, cms__remark__begin); |
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HS_DTRACE_PROBE_DECL(hs_private, cms__remark__end); |
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||
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////////////////////////////////////////////////////////// |
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// Methods in abstract class VM_CMS_Operation |
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////////////////////////////////////////////////////////// |
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void VM_CMS_Operation::acquire_pending_list_lock() { |
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// The caller may block while communicating |
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// with the SLT thread in order to acquire/release the PLL. |
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ConcurrentMarkSweepThread::slt()-> |
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manipulatePLL(SurrogateLockerThread::acquirePLL); |
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} |
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void VM_CMS_Operation::release_and_notify_pending_list_lock() { |
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// The caller may block while communicating |
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// with the SLT thread in order to acquire/release the PLL. |
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ConcurrentMarkSweepThread::slt()-> |
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manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); |
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} |
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void VM_CMS_Operation::verify_before_gc() { |
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if (VerifyBeforeGC && |
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GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { |
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HandleMark hm; |
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FreelistLocker x(_collector); |
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MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); |
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Universe::heap()->prepare_for_verify(); |
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Universe::verify(true); |
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} |
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} |
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void VM_CMS_Operation::verify_after_gc() { |
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if (VerifyAfterGC && |
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GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { |
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HandleMark hm; |
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FreelistLocker x(_collector); |
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MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); |
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Universe::verify(true); |
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} |
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} |
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bool VM_CMS_Operation::lost_race() const { |
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if (CMSCollector::abstract_state() == CMSCollector::Idling) { |
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// We lost a race to a foreground collection |
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// -- there's nothing to do |
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return true; |
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} |
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assert(CMSCollector::abstract_state() == legal_state(), |
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"Inconsistent collector state?"); |
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return false; |
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} |
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bool VM_CMS_Operation::doit_prologue() { |
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assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); |
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assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); |
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assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), |
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"Possible deadlock"); |
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if (needs_pll()) { |
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acquire_pending_list_lock(); |
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} |
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// Get the Heap_lock after the pending_list_lock. |
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Heap_lock->lock(); |
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if (lost_race()) { |
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assert(_prologue_succeeded == false, "Initialized in c'tor"); |
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Heap_lock->unlock(); |
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if (needs_pll()) { |
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release_and_notify_pending_list_lock(); |
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} |
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} else { |
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_prologue_succeeded = true; |
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} |
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return _prologue_succeeded; |
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} |
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void VM_CMS_Operation::doit_epilogue() { |
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assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); |
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assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); |
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assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), |
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"Possible deadlock"); |
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// Release the Heap_lock first. |
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Heap_lock->unlock(); |
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if (needs_pll()) { |
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release_and_notify_pending_list_lock(); |
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} |
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} |
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////////////////////////////////////////////////////////// |
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// Methods in class VM_CMS_Initial_Mark |
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////////////////////////////////////////////////////////// |
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void VM_CMS_Initial_Mark::doit() { |
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if (lost_race()) { |
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// Nothing to do. |
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return; |
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} |
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HS_DTRACE_PROBE(hs_private, cms__initmark__begin); |
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GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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GCCauseSetter gccs(gch, GCCause::_cms_initial_mark); |
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VM_CMS_Operation::verify_before_gc(); |
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IsGCActiveMark x; // stop-world GC active |
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_collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial); |
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VM_CMS_Operation::verify_after_gc(); |
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HS_DTRACE_PROBE(hs_private, cms__initmark__end); |
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} |
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////////////////////////////////////////////////////////// |
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// Methods in class VM_CMS_Final_Remark_Operation |
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////////////////////////////////////////////////////////// |
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void VM_CMS_Final_Remark::doit() { |
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if (lost_race()) { |
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// Nothing to do. |
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return; |
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} |
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HS_DTRACE_PROBE(hs_private, cms__remark__begin); |
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GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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GCCauseSetter gccs(gch, GCCause::_cms_final_remark); |
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VM_CMS_Operation::verify_before_gc(); |
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IsGCActiveMark x; // stop-world GC active |
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_collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal); |
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VM_CMS_Operation::verify_after_gc(); |
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HS_DTRACE_PROBE(hs_private, cms__remark__end); |
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} |
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// VM operation to invoke a concurrent collection of a |
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// GenCollectedHeap heap. |
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void VM_GenCollectFullConcurrent::doit() { |
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assert(Thread::current()->is_VM_thread(), "Should be VM thread"); |
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assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected"); |
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GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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if (_gc_count_before == gch->total_collections()) { |
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// The "full" of do_full_collection call below "forces" |
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// a collection; the second arg, 0, below ensures that |
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// only the young gen is collected. XXX In the future, |
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// we'll probably need to have something in this interface |
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// to say do this only if we are sure we will not bail |
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// out to a full collection in this attempt, but that's |
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// for the future. |
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assert(SafepointSynchronize::is_at_safepoint(), |
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"We can only be executing this arm of if at a safepoint"); |
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GCCauseSetter gccs(gch, _gc_cause); |
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gch->do_full_collection(gch->must_clear_all_soft_refs(), |
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0 /* collect only youngest gen */); |
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} // Else no need for a foreground young gc |
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assert((_gc_count_before < gch->total_collections()) || |
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(GC_locker::is_active() /* gc may have been skipped */ |
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&& (_gc_count_before == gch->total_collections())), |
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"total_collections() should be monotonically increasing"); |
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MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); |
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if (gch->total_full_collections() == _full_gc_count_before) { |
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// Disable iCMS until the full collection is done. |
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CMSCollector::disable_icms(); |
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// In case CMS thread was in icms_wait(), wake it up. |
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CMSCollector::start_icms(); |
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// Nudge the CMS thread to start a concurrent collection. |
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CMSCollector::request_full_gc(_full_gc_count_before); |
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} else { |
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FullGCCount_lock->notify_all(); // Inform the Java thread its work is done |
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} |
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} |
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bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const { |
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Thread* thr = Thread::current(); |
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assert(thr != NULL, "Unexpected tid"); |
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if (!thr->is_Java_thread()) { |
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assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread"); |
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GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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if (_gc_count_before != gch->total_collections()) { |
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// No need to do a young gc, we'll just nudge the CMS thread |
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// in the doit() method above, to be executed soon. |
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assert(_gc_count_before < gch->total_collections(), |
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"total_collections() should be monotnically increasing"); |
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return false; // no need for foreground young gc |
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} |
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} |
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return true; // may still need foreground young gc |
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} |
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void VM_GenCollectFullConcurrent::doit_epilogue() { |
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Thread* thr = Thread::current(); |
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assert(thr->is_Java_thread(), "just checking"); |
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JavaThread* jt = (JavaThread*)thr; |
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// Release the Heap_lock first. |
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Heap_lock->unlock(); |
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release_and_notify_pending_list_lock(); |
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// It is fine to test whether completed collections has |
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// exceeded our request count without locking because |
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// the completion count is monotonically increasing; |
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// this will break for very long-running apps when the |
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// count overflows and wraps around. XXX fix me !!! |
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// e.g. at the rate of 1 full gc per ms, this could |
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// overflow in about 1000 years. |
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GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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if (_gc_cause != GCCause::_gc_locker && |
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gch->total_full_collections_completed() <= _full_gc_count_before) { |
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// maybe we should change the condition to test _gc_cause == |
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// GCCause::_java_lang_system_gc, instead of |
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// _gc_cause != GCCause::_gc_locker |
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assert(_gc_cause == GCCause::_java_lang_system_gc, |
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"the only way to get here if this was a System.gc()-induced GC"); |
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assert(ExplicitGCInvokesConcurrent, "Error"); |
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// Now, wait for witnessing concurrent gc cycle to complete, |
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// but do so in native mode, because we want to lock the |
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// FullGCEvent_lock, which may be needed by the VM thread |
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// or by the CMS thread, so we do not want to be suspended |
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// while holding that lock. |
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ThreadToNativeFromVM native(jt); |
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MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); |
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// Either a concurrent or a stop-world full gc is sufficient |
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// witness to our request. |
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while (gch->total_full_collections_completed() <= _full_gc_count_before) { |
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FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); |
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} |
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} |
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// Enable iCMS back. |
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CMSCollector::enable_icms(); |
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} |