duke@435: /*
sla@5237:  * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp"
stefank@2314: #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
stefank@2314: #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
sla@5237: #include "gc_implementation/shared/gcTimer.hpp"
sla@5237: #include "gc_implementation/shared/gcTraceTime.hpp"
stefank@2314: #include "gc_implementation/shared/isGCActiveMark.hpp"
stefank@2314: #include "memory/gcLocker.inline.hpp"
stefank@2314: #include "runtime/interfaceSupport.hpp"
sla@5237: #include "runtime/os.hpp"
stefank@2314: #include "utilities/dtrace.hpp"
dcubed@3202: 
dcubed@3202: 
dcubed@3202: #ifndef USDT2
duke@435: HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__begin);
duke@435: HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__end);
duke@435: 
duke@435: HS_DTRACE_PROBE_DECL(hs_private, cms__remark__begin);
duke@435: HS_DTRACE_PROBE_DECL(hs_private, cms__remark__end);
dcubed@3202: #endif /* !USDT2 */
duke@435: 
duke@435: //////////////////////////////////////////////////////////
duke@435: // Methods in abstract class VM_CMS_Operation
duke@435: //////////////////////////////////////////////////////////
duke@435: void VM_CMS_Operation::acquire_pending_list_lock() {
duke@435:   // The caller may block while communicating
duke@435:   // with the SLT thread in order to acquire/release the PLL.
duke@435:   ConcurrentMarkSweepThread::slt()->
duke@435:     manipulatePLL(SurrogateLockerThread::acquirePLL);
duke@435: }
duke@435: 
duke@435: void VM_CMS_Operation::release_and_notify_pending_list_lock() {
duke@435:   // The caller may block while communicating
duke@435:   // with the SLT thread in order to acquire/release the PLL.
duke@435:   ConcurrentMarkSweepThread::slt()->
duke@435:     manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
duke@435: }
duke@435: 
duke@435: void VM_CMS_Operation::verify_before_gc() {
duke@435:   if (VerifyBeforeGC &&
duke@435:       GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
sla@5237:     GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm);
duke@435:     HandleMark hm;
duke@435:     FreelistLocker x(_collector);
duke@435:     MutexLockerEx  y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
duke@435:     Universe::heap()->prepare_for_verify();
johnc@4176:     Universe::verify();
duke@435:   }
duke@435: }
duke@435: 
duke@435: void VM_CMS_Operation::verify_after_gc() {
duke@435:   if (VerifyAfterGC &&
duke@435:       GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
sla@5237:     GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm);
duke@435:     HandleMark hm;
duke@435:     FreelistLocker x(_collector);
duke@435:     MutexLockerEx  y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
johnc@4176:     Universe::verify();
duke@435:   }
duke@435: }
duke@435: 
duke@435: bool VM_CMS_Operation::lost_race() const {
duke@435:   if (CMSCollector::abstract_state() == CMSCollector::Idling) {
duke@435:     // We lost a race to a foreground collection
duke@435:     // -- there's nothing to do
duke@435:     return true;
duke@435:   }
duke@435:   assert(CMSCollector::abstract_state() == legal_state(),
duke@435:          "Inconsistent collector state?");
duke@435:   return false;
duke@435: }
duke@435: 
duke@435: bool VM_CMS_Operation::doit_prologue() {
duke@435:   assert(Thread::current()->is_ConcurrentGC_thread(), "just checking");
duke@435:   assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock");
duke@435:   assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
duke@435:          "Possible deadlock");
duke@435: 
duke@435:   if (needs_pll()) {
duke@435:     acquire_pending_list_lock();
duke@435:   }
duke@435:   // Get the Heap_lock after the pending_list_lock.
duke@435:   Heap_lock->lock();
duke@435:   if (lost_race()) {
duke@435:     assert(_prologue_succeeded == false, "Initialized in c'tor");
duke@435:     Heap_lock->unlock();
duke@435:     if (needs_pll()) {
duke@435:       release_and_notify_pending_list_lock();
duke@435:     }
duke@435:   } else {
duke@435:     _prologue_succeeded = true;
duke@435:   }
duke@435:   return _prologue_succeeded;
duke@435: }
duke@435: 
duke@435: void VM_CMS_Operation::doit_epilogue() {
duke@435:   assert(Thread::current()->is_ConcurrentGC_thread(), "just checking");
duke@435:   assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock");
duke@435:   assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
duke@435:          "Possible deadlock");
duke@435: 
duke@435:   // Release the Heap_lock first.
duke@435:   Heap_lock->unlock();
duke@435:   if (needs_pll()) {
duke@435:     release_and_notify_pending_list_lock();
duke@435:   }
duke@435: }
duke@435: 
duke@435: //////////////////////////////////////////////////////////
duke@435: // Methods in class VM_CMS_Initial_Mark
duke@435: //////////////////////////////////////////////////////////
duke@435: void VM_CMS_Initial_Mark::doit() {
duke@435:   if (lost_race()) {
duke@435:     // Nothing to do.
duke@435:     return;
duke@435:   }
dcubed@3202: #ifndef USDT2
duke@435:   HS_DTRACE_PROBE(hs_private, cms__initmark__begin);
dcubed@3202: #else /* USDT2 */
dcubed@3202:   HS_PRIVATE_CMS_INITMARK_BEGIN(
dcubed@3202:                                 );
dcubed@3202: #endif /* USDT2 */
duke@435: 
mgronlun@6131:   _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark");
sla@5237: 
duke@435:   GenCollectedHeap* gch = GenCollectedHeap::heap();
duke@435:   GCCauseSetter gccs(gch, GCCause::_cms_initial_mark);
duke@435: 
duke@435:   VM_CMS_Operation::verify_before_gc();
duke@435: 
duke@435:   IsGCActiveMark x; // stop-world GC active
brutisso@3767:   _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, gch->gc_cause());
duke@435: 
duke@435:   VM_CMS_Operation::verify_after_gc();
sla@5237: 
mgronlun@6131:   _collector->_gc_timer_cm->register_gc_pause_end();
sla@5237: 
dcubed@3202: #ifndef USDT2
duke@435:   HS_DTRACE_PROBE(hs_private, cms__initmark__end);
dcubed@3202: #else /* USDT2 */
dcubed@3202:   HS_PRIVATE_CMS_INITMARK_END(
dcubed@3202:                                 );
dcubed@3202: #endif /* USDT2 */
duke@435: }
duke@435: 
duke@435: //////////////////////////////////////////////////////////
duke@435: // Methods in class VM_CMS_Final_Remark_Operation
duke@435: //////////////////////////////////////////////////////////
duke@435: void VM_CMS_Final_Remark::doit() {
duke@435:   if (lost_race()) {
duke@435:     // Nothing to do.
duke@435:     return;
duke@435:   }
dcubed@3202: #ifndef USDT2
duke@435:   HS_DTRACE_PROBE(hs_private, cms__remark__begin);
dcubed@3202: #else /* USDT2 */
dcubed@3202:   HS_PRIVATE_CMS_REMARK_BEGIN(
dcubed@3202:                                 );
dcubed@3202: #endif /* USDT2 */
duke@435: 
mgronlun@6131:   _collector->_gc_timer_cm->register_gc_pause_start("Final Mark");
sla@5237: 
duke@435:   GenCollectedHeap* gch = GenCollectedHeap::heap();
duke@435:   GCCauseSetter gccs(gch, GCCause::_cms_final_remark);
duke@435: 
duke@435:   VM_CMS_Operation::verify_before_gc();
duke@435: 
duke@435:   IsGCActiveMark x; // stop-world GC active
brutisso@3767:   _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause());
duke@435: 
duke@435:   VM_CMS_Operation::verify_after_gc();
sla@5237: 
sla@5237:   _collector->save_heap_summary();
mgronlun@6131:   _collector->_gc_timer_cm->register_gc_pause_end();
sla@5237: 
dcubed@3202: #ifndef USDT2
duke@435:   HS_DTRACE_PROBE(hs_private, cms__remark__end);
dcubed@3202: #else /* USDT2 */
dcubed@3202:   HS_PRIVATE_CMS_REMARK_END(
dcubed@3202:                                 );
dcubed@3202: #endif /* USDT2 */
duke@435: }
duke@435: 
duke@435: // VM operation to invoke a concurrent collection of a
duke@435: // GenCollectedHeap heap.
duke@435: void VM_GenCollectFullConcurrent::doit() {
duke@435:   assert(Thread::current()->is_VM_thread(), "Should be VM thread");
ysr@1875:   assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected");
duke@435: 
duke@435:   GenCollectedHeap* gch = GenCollectedHeap::heap();
duke@435:   if (_gc_count_before == gch->total_collections()) {
duke@435:     // The "full" of do_full_collection call below "forces"
duke@435:     // a collection; the second arg, 0, below ensures that
duke@435:     // only the young gen is collected. XXX In the future,
duke@435:     // we'll probably need to have something in this interface
duke@435:     // to say do this only if we are sure we will not bail
duke@435:     // out to a full collection in this attempt, but that's
duke@435:     // for the future.
duke@435:     assert(SafepointSynchronize::is_at_safepoint(),
duke@435:       "We can only be executing this arm of if at a safepoint");
duke@435:     GCCauseSetter gccs(gch, _gc_cause);
duke@435:     gch->do_full_collection(gch->must_clear_all_soft_refs(),
duke@435:                             0 /* collect only youngest gen */);
duke@435:   } // Else no need for a foreground young gc
duke@435:   assert((_gc_count_before < gch->total_collections()) ||
duke@435:          (GC_locker::is_active() /* gc may have been skipped */
duke@435:           && (_gc_count_before == gch->total_collections())),
duke@435:          "total_collections() should be monotonically increasing");
duke@435: 
duke@435:   MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
ysr@2647:   assert(_full_gc_count_before <= gch->total_full_collections(), "Error");
duke@435:   if (gch->total_full_collections() == _full_gc_count_before) {
ysr@2647:     // Disable iCMS until the full collection is done, and
ysr@2647:     // remember that we did so.
duke@435:     CMSCollector::disable_icms();
ysr@2647:     _disabled_icms = true;
duke@435:     // In case CMS thread was in icms_wait(), wake it up.
duke@435:     CMSCollector::start_icms();
ysr@1875:     // Nudge the CMS thread to start a concurrent collection.
sla@5237:     CMSCollector::request_full_gc(_full_gc_count_before, _gc_cause);
duke@435:   } else {
ysr@2647:     assert(_full_gc_count_before < gch->total_full_collections(), "Error");
duke@435:     FullGCCount_lock->notify_all();  // Inform the Java thread its work is done
duke@435:   }
duke@435: }
duke@435: 
duke@435: bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const {
duke@435:   Thread* thr = Thread::current();
duke@435:   assert(thr != NULL, "Unexpected tid");
duke@435:   if (!thr->is_Java_thread()) {
duke@435:     assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread");
duke@435:     GenCollectedHeap* gch = GenCollectedHeap::heap();
duke@435:     if (_gc_count_before != gch->total_collections()) {
duke@435:       // No need to do a young gc, we'll just nudge the CMS thread
duke@435:       // in the doit() method above, to be executed soon.
duke@435:       assert(_gc_count_before < gch->total_collections(),
duke@435:              "total_collections() should be monotnically increasing");
duke@435:       return false;  // no need for foreground young gc
duke@435:     }
duke@435:   }
duke@435:   return true;       // may still need foreground young gc
duke@435: }
duke@435: 
duke@435: 
duke@435: void VM_GenCollectFullConcurrent::doit_epilogue() {
duke@435:   Thread* thr = Thread::current();
duke@435:   assert(thr->is_Java_thread(), "just checking");
duke@435:   JavaThread* jt = (JavaThread*)thr;
duke@435:   // Release the Heap_lock first.
duke@435:   Heap_lock->unlock();
duke@435:   release_and_notify_pending_list_lock();
duke@435: 
duke@435:   // It is fine to test whether completed collections has
duke@435:   // exceeded our request count without locking because
duke@435:   // the completion count is monotonically increasing;
duke@435:   // this will break for very long-running apps when the
duke@435:   // count overflows and wraps around. XXX fix me !!!
duke@435:   // e.g. at the rate of 1 full gc per ms, this could
duke@435:   // overflow in about 1000 years.
duke@435:   GenCollectedHeap* gch = GenCollectedHeap::heap();
ysr@1875:   if (_gc_cause != GCCause::_gc_locker &&
ysr@1875:       gch->total_full_collections_completed() <= _full_gc_count_before) {
tonyp@2011:     // maybe we should change the condition to test _gc_cause ==
tonyp@2011:     // GCCause::_java_lang_system_gc, instead of
tonyp@2011:     // _gc_cause != GCCause::_gc_locker
tonyp@2011:     assert(_gc_cause == GCCause::_java_lang_system_gc,
tonyp@2011:            "the only way to get here if this was a System.gc()-induced GC");
ysr@1875:     assert(ExplicitGCInvokesConcurrent, "Error");
duke@435:     // Now, wait for witnessing concurrent gc cycle to complete,
duke@435:     // but do so in native mode, because we want to lock the
duke@435:     // FullGCEvent_lock, which may be needed by the VM thread
duke@435:     // or by the CMS thread, so we do not want to be suspended
duke@435:     // while holding that lock.
duke@435:     ThreadToNativeFromVM native(jt);
duke@435:     MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
duke@435:     // Either a concurrent or a stop-world full gc is sufficient
duke@435:     // witness to our request.
duke@435:     while (gch->total_full_collections_completed() <= _full_gc_count_before) {
duke@435:       FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
duke@435:     }
duke@435:   }
ysr@2647:   // Enable iCMS back if we disabled it earlier.
ysr@2647:   if (_disabled_icms) {
ysr@2647:     CMSCollector::enable_icms();
ysr@2647:   }
duke@435: }