aoqi@0: /*
aoqi@0:  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
aoqi@0: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
aoqi@0: #include "gc_implementation/g1/g1CollectorPolicy.hpp"
aoqi@0: #include "gc_implementation/g1/g1Log.hpp"
aoqi@0: #include "gc_implementation/g1/g1MMUTracker.hpp"
aoqi@0: #include "gc_implementation/g1/vm_operations_g1.hpp"
aoqi@0: #include "memory/resourceArea.hpp"
aoqi@0: #include "runtime/vmThread.hpp"
aoqi@0: 
aoqi@0: // ======= Concurrent Mark Thread ========
aoqi@0: 
aoqi@0: // The CM thread is created when the G1 garbage collector is used
aoqi@0: 
aoqi@0: SurrogateLockerThread*
aoqi@0:      ConcurrentMarkThread::_slt = NULL;
aoqi@0: 
aoqi@0: ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) :
aoqi@0:   ConcurrentGCThread(),
aoqi@0:   _cm(cm),
aoqi@0:   _started(false),
aoqi@0:   _in_progress(false),
aoqi@0:   _vtime_accum(0.0),
aoqi@0:   _vtime_mark_accum(0.0) {
aoqi@0:   create_and_start();
aoqi@0: }
aoqi@0: 
aoqi@0: class CMCheckpointRootsFinalClosure: public VoidClosure {
aoqi@0: 
aoqi@0:   ConcurrentMark* _cm;
aoqi@0: public:
aoqi@0: 
aoqi@0:   CMCheckpointRootsFinalClosure(ConcurrentMark* cm) :
aoqi@0:     _cm(cm) {}
aoqi@0: 
aoqi@0:   void do_void(){
aoqi@0:     _cm->checkpointRootsFinal(false); // !clear_all_soft_refs
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: class CMCleanUp: public VoidClosure {
aoqi@0:   ConcurrentMark* _cm;
aoqi@0: public:
aoqi@0: 
aoqi@0:   CMCleanUp(ConcurrentMark* cm) :
aoqi@0:     _cm(cm) {}
aoqi@0: 
aoqi@0:   void do_void(){
aoqi@0:     _cm->cleanup();
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: 
aoqi@0: void ConcurrentMarkThread::run() {
aoqi@0:   initialize_in_thread();
aoqi@0:   _vtime_start = os::elapsedVTime();
aoqi@0:   wait_for_universe_init();
aoqi@0: 
aoqi@0:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
aoqi@0:   G1CollectorPolicy* g1_policy = g1h->g1_policy();
aoqi@0:   G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
aoqi@0:   Thread *current_thread = Thread::current();
aoqi@0: 
aoqi@0:   while (!_should_terminate) {
aoqi@0:     // wait until started is set.
aoqi@0:     sleepBeforeNextCycle();
aoqi@0:     if (_should_terminate) {
aoqi@0:       break;
aoqi@0:     }
aoqi@0: 
aoqi@0:     {
aoqi@0:       ResourceMark rm;
aoqi@0:       HandleMark   hm;
aoqi@0:       double cycle_start = os::elapsedVTime();
aoqi@0: 
aoqi@0:       // We have to ensure that we finish scanning the root regions
aoqi@0:       // before the next GC takes place. To ensure this we have to
aoqi@0:       // make sure that we do not join the STS until the root regions
aoqi@0:       // have been scanned. If we did then it's possible that a
aoqi@0:       // subsequent GC could block us from joining the STS and proceed
aoqi@0:       // without the root regions have been scanned which would be a
aoqi@0:       // correctness issue.
aoqi@0: 
aoqi@0:       double scan_start = os::elapsedTime();
aoqi@0:       if (!cm()->has_aborted()) {
aoqi@0:         if (G1Log::fine()) {
aoqi@0:           gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:           gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:           gclog_or_tty->print_cr("[GC concurrent-root-region-scan-start]");
aoqi@0:         }
aoqi@0: 
aoqi@0:         _cm->scanRootRegions();
aoqi@0: 
aoqi@0:         double scan_end = os::elapsedTime();
aoqi@0:         if (G1Log::fine()) {
aoqi@0:           gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:           gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:           gclog_or_tty->print_cr("[GC concurrent-root-region-scan-end, %1.7lf secs]",
aoqi@0:                                  scan_end - scan_start);
aoqi@0:         }
aoqi@0:       }
aoqi@0: 
aoqi@0:       double mark_start_sec = os::elapsedTime();
aoqi@0:       if (G1Log::fine()) {
aoqi@0:         gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:         gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:         gclog_or_tty->print_cr("[GC concurrent-mark-start]");
aoqi@0:       }
aoqi@0: 
aoqi@0:       int iter = 0;
aoqi@0:       do {
aoqi@0:         iter++;
aoqi@0:         if (!cm()->has_aborted()) {
aoqi@0:           _cm->markFromRoots();
aoqi@0:         }
aoqi@0: 
aoqi@0:         double mark_end_time = os::elapsedVTime();
aoqi@0:         double mark_end_sec = os::elapsedTime();
aoqi@0:         _vtime_mark_accum += (mark_end_time - cycle_start);
aoqi@0:         if (!cm()->has_aborted()) {
aoqi@0:           if (g1_policy->adaptive_young_list_length()) {
aoqi@0:             double now = os::elapsedTime();
aoqi@0:             double remark_prediction_ms = g1_policy->predict_remark_time_ms();
aoqi@0:             jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
aoqi@0:             os::sleep(current_thread, sleep_time_ms, false);
aoqi@0:           }
aoqi@0: 
aoqi@0:           if (G1Log::fine()) {
aoqi@0:             gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:             gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:             gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf secs]",
aoqi@0:                                       mark_end_sec - mark_start_sec);
aoqi@0:           }
aoqi@0: 
aoqi@0:           CMCheckpointRootsFinalClosure final_cl(_cm);
aoqi@0:           VM_CGC_Operation op(&final_cl, "GC remark", true /* needs_pll */);
aoqi@0:           VMThread::execute(&op);
aoqi@0:         }
aoqi@0:         if (cm()->restart_for_overflow()) {
aoqi@0:           if (G1TraceMarkStackOverflow) {
aoqi@0:             gclog_or_tty->print_cr("Restarting conc marking because of MS overflow "
aoqi@0:                                    "in remark (restart #%d).", iter);
aoqi@0:           }
aoqi@0:           if (G1Log::fine()) {
aoqi@0:             gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:             gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:             gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
aoqi@0:           }
aoqi@0:         }
aoqi@0:       } while (cm()->restart_for_overflow());
aoqi@0: 
aoqi@0:       double end_time = os::elapsedVTime();
aoqi@0:       // Update the total virtual time before doing this, since it will try
aoqi@0:       // to measure it to get the vtime for this marking.  We purposely
aoqi@0:       // neglect the presumably-short "completeCleanup" phase here.
aoqi@0:       _vtime_accum = (end_time - _vtime_start);
aoqi@0: 
aoqi@0:       if (!cm()->has_aborted()) {
aoqi@0:         if (g1_policy->adaptive_young_list_length()) {
aoqi@0:           double now = os::elapsedTime();
aoqi@0:           double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
aoqi@0:           jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
aoqi@0:           os::sleep(current_thread, sleep_time_ms, false);
aoqi@0:         }
aoqi@0: 
aoqi@0:         CMCleanUp cl_cl(_cm);
aoqi@0:         VM_CGC_Operation op(&cl_cl, "GC cleanup", false /* needs_pll */);
aoqi@0:         VMThread::execute(&op);
aoqi@0:       } else {
aoqi@0:         // We don't want to update the marking status if a GC pause
aoqi@0:         // is already underway.
aoqi@0:         _sts.join();
aoqi@0:         g1h->set_marking_complete();
aoqi@0:         _sts.leave();
aoqi@0:       }
aoqi@0: 
aoqi@0:       // Check if cleanup set the free_regions_coming flag. If it
aoqi@0:       // hasn't, we can just skip the next step.
aoqi@0:       if (g1h->free_regions_coming()) {
aoqi@0:         // The following will finish freeing up any regions that we
aoqi@0:         // found to be empty during cleanup. We'll do this part
aoqi@0:         // without joining the suspendible set. If an evacuation pause
aoqi@0:         // takes place, then we would carry on freeing regions in
aoqi@0:         // case they are needed by the pause. If a Full GC takes
aoqi@0:         // place, it would wait for us to process the regions
aoqi@0:         // reclaimed by cleanup.
aoqi@0: 
aoqi@0:         double cleanup_start_sec = os::elapsedTime();
aoqi@0:         if (G1Log::fine()) {
aoqi@0:           gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:           gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:           gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
aoqi@0:         }
aoqi@0: 
aoqi@0:         // Now do the concurrent cleanup operation.
aoqi@0:         _cm->completeCleanup();
aoqi@0: 
aoqi@0:         // Notify anyone who's waiting that there are no more free
aoqi@0:         // regions coming. We have to do this before we join the STS
aoqi@0:         // (in fact, we should not attempt to join the STS in the
aoqi@0:         // interval between finishing the cleanup pause and clearing
aoqi@0:         // the free_regions_coming flag) otherwise we might deadlock:
aoqi@0:         // a GC worker could be blocked waiting for the notification
aoqi@0:         // whereas this thread will be blocked for the pause to finish
aoqi@0:         // while it's trying to join the STS, which is conditional on
aoqi@0:         // the GC workers finishing.
aoqi@0:         g1h->reset_free_regions_coming();
aoqi@0: 
aoqi@0:         double cleanup_end_sec = os::elapsedTime();
aoqi@0:         if (G1Log::fine()) {
aoqi@0:           gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:           gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:           gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf secs]",
aoqi@0:                                  cleanup_end_sec - cleanup_start_sec);
aoqi@0:         }
aoqi@0:       }
aoqi@0:       guarantee(cm()->cleanup_list_is_empty(),
aoqi@0:                 "at this point there should be no regions on the cleanup list");
aoqi@0: 
aoqi@0:       // There is a tricky race before recording that the concurrent
aoqi@0:       // cleanup has completed and a potential Full GC starting around
aoqi@0:       // the same time. We want to make sure that the Full GC calls
aoqi@0:       // abort() on concurrent mark after
aoqi@0:       // record_concurrent_mark_cleanup_completed(), since abort() is
aoqi@0:       // the method that will reset the concurrent mark state. If we
aoqi@0:       // end up calling record_concurrent_mark_cleanup_completed()
aoqi@0:       // after abort() then we might incorrectly undo some of the work
aoqi@0:       // abort() did. Checking the has_aborted() flag after joining
aoqi@0:       // the STS allows the correct ordering of the two methods. There
aoqi@0:       // are two scenarios:
aoqi@0:       //
aoqi@0:       // a) If we reach here before the Full GC, the fact that we have
aoqi@0:       // joined the STS means that the Full GC cannot start until we
aoqi@0:       // leave the STS, so record_concurrent_mark_cleanup_completed()
aoqi@0:       // will complete before abort() is called.
aoqi@0:       //
aoqi@0:       // b) If we reach here during the Full GC, we'll be held up from
aoqi@0:       // joining the STS until the Full GC is done, which means that
aoqi@0:       // abort() will have completed and has_aborted() will return
aoqi@0:       // true to prevent us from calling
aoqi@0:       // record_concurrent_mark_cleanup_completed() (and, in fact, it's
aoqi@0:       // not needed any more as the concurrent mark state has been
aoqi@0:       // already reset).
aoqi@0:       _sts.join();
aoqi@0:       if (!cm()->has_aborted()) {
aoqi@0:         g1_policy->record_concurrent_mark_cleanup_completed();
aoqi@0:       }
aoqi@0:       _sts.leave();
aoqi@0: 
aoqi@0:       if (cm()->has_aborted()) {
aoqi@0:         if (G1Log::fine()) {
aoqi@0:           gclog_or_tty->date_stamp(PrintGCDateStamps);
aoqi@0:           gclog_or_tty->stamp(PrintGCTimeStamps);
aoqi@0:           gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
aoqi@0:         }
aoqi@0:       }
aoqi@0: 
aoqi@0:       // We now want to allow clearing of the marking bitmap to be
aoqi@0:       // suspended by a collection pause.
aoqi@0:       _sts.join();
aoqi@0:       _cm->clearNextBitmap();
aoqi@0:       _sts.leave();
aoqi@0:     }
aoqi@0: 
aoqi@0:     // Update the number of full collections that have been
aoqi@0:     // completed. This will also notify the FullGCCount_lock in case a
aoqi@0:     // Java thread is waiting for a full GC to happen (e.g., it
aoqi@0:     // called System.gc() with +ExplicitGCInvokesConcurrent).
aoqi@0:     _sts.join();
aoqi@0:     g1h->increment_old_marking_cycles_completed(true /* concurrent */);
aoqi@0:     g1h->register_concurrent_cycle_end();
aoqi@0:     _sts.leave();
aoqi@0:   }
aoqi@0:   assert(_should_terminate, "just checking");
aoqi@0: 
aoqi@0:   terminate();
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: void ConcurrentMarkThread::yield() {
aoqi@0:   _sts.yield("Concurrent Mark");
aoqi@0: }
aoqi@0: 
aoqi@0: void ConcurrentMarkThread::stop() {
aoqi@0:   {
aoqi@0:     MutexLockerEx ml(Terminator_lock);
aoqi@0:     _should_terminate = true;
aoqi@0:   }
aoqi@0: 
aoqi@0:   {
aoqi@0:     MutexLockerEx ml(CGC_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:     CGC_lock->notify_all();
aoqi@0:   }
aoqi@0: 
aoqi@0:   {
aoqi@0:     MutexLockerEx ml(Terminator_lock);
aoqi@0:     while (!_has_terminated) {
aoqi@0:       Terminator_lock->wait();
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void ConcurrentMarkThread::print() const {
aoqi@0:   print_on(tty);
aoqi@0: }
aoqi@0: 
aoqi@0: void ConcurrentMarkThread::print_on(outputStream* st) const {
aoqi@0:   st->print("\"G1 Main Concurrent Mark GC Thread\" ");
aoqi@0:   Thread::print_on(st);
aoqi@0:   st->cr();
aoqi@0: }
aoqi@0: 
aoqi@0: void ConcurrentMarkThread::sleepBeforeNextCycle() {
aoqi@0:   // We join here because we don't want to do the "shouldConcurrentMark()"
aoqi@0:   // below while the world is otherwise stopped.
aoqi@0:   assert(!in_progress(), "should have been cleared");
aoqi@0: 
aoqi@0:   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:   while (!started() && !_should_terminate) {
aoqi@0:     CGC_lock->wait(Mutex::_no_safepoint_check_flag);
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (started()) {
aoqi@0:     set_in_progress();
aoqi@0:     clear_started();
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // Note: As is the case with CMS - this method, although exported
aoqi@0: // by the ConcurrentMarkThread, which is a non-JavaThread, can only
aoqi@0: // be called by a JavaThread. Currently this is done at vm creation
aoqi@0: // time (post-vm-init) by the main/Primordial (Java)Thread.
aoqi@0: // XXX Consider changing this in the future to allow the CM thread
aoqi@0: // itself to create this thread?
aoqi@0: void ConcurrentMarkThread::makeSurrogateLockerThread(TRAPS) {
aoqi@0:   assert(UseG1GC, "SLT thread needed only for concurrent GC");
aoqi@0:   assert(THREAD->is_Java_thread(), "must be a Java thread");
aoqi@0:   assert(_slt == NULL, "SLT already created");
aoqi@0:   _slt = SurrogateLockerThread::make(THREAD);
aoqi@0: }