jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/vm_operations

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp@4dfb2df418f2 (annotated)

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp

Thu, 22 Sep 2011 10:57:37 -0700

author: johnc
date: Thu, 22 Sep 2011 10:57:37 -0700
changeset 3175: 4dfb2df418f2
parent 3114: 20213c8a3c40
child 3218: db89aa49298f
permissions: -rw-r--r--

6484982: G1: process references during evacuation pauses
Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

 /*
  * Copyright (c) 2001, 2011, 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
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 #include "precompiled.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
 #include "gc_implementation/shared/isGCActiveMark.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
 #include "runtime/interfaceSupport.hpp"
 VM_G1CollectForAllocation::VM_G1CollectForAllocation(
                                                   unsigned int gc_count_before,
                                                   size_t word_size)
   : VM_G1OperationWithAllocRequest(gc_count_before, word_size) {
   guarantee(word_size > 0, "an allocation should always be requested");
 }
 void VM_G1CollectForAllocation::doit() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);
   assert(_result == NULL || _pause_succeeded,
          "if we get back a result, the pause should have succeeded");
 }
 void VM_G1CollectFull::doit() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   GCCauseSetter x(g1h, _gc_cause);
   g1h->do_full_collection(false /* clear_all_soft_refs */);
 }
 VM_G1IncCollectionPause::VM_G1IncCollectionPause(
                                       unsigned int   gc_count_before,
                                       size_t         word_size,
                                       bool           should_initiate_conc_mark,
                                       double         target_pause_time_ms,
                                       GCCause::Cause gc_cause)
   : VM_G1OperationWithAllocRequest(gc_count_before, word_size),
     _should_initiate_conc_mark(should_initiate_conc_mark),
     _target_pause_time_ms(target_pause_time_ms),
     _full_collections_completed_before(0) {
   guarantee(target_pause_time_ms > 0.0,
             err_msg("target_pause_time_ms = %1.6lf should be positive",
                     target_pause_time_ms));
   guarantee(word_size == 0 || gc_cause == GCCause::_g1_inc_collection_pause,
             "we can only request an allocation if the GC cause is for "
             "an incremental GC pause");
   _gc_cause = gc_cause;
 }
 void VM_G1IncCollectionPause::doit() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   assert(!_should_initiate_conc_mark ||
   ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
    (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),
          "only a GC locker or a System.gc() induced GC should start a cycle");
   if (_word_size > 0) {
     // An allocation has been requested. So, try to do that first.
     _result = g1h->attempt_allocation_at_safepoint(_word_size,
                                      false /* expect_null_cur_alloc_region */);
     if (_result != NULL) {
       // If we can successfully allocate before we actually do the
       // pause then we will consider this pause successful.
       _pause_succeeded = true;
       return;
     }
   }
   GCCauseSetter x(g1h, _gc_cause);
   if (_should_initiate_conc_mark) {
     // It's safer to read full_collections_completed() here, given
     // that noone else will be updating it concurrently. Since we'll
     // only need it if we're initiating a marking cycle, no point in
     // setting it earlier.
     _full_collections_completed_before = g1h->full_collections_completed();
     // At this point we are supposed to start a concurrent cycle. We
     // will do so if one is not already in progress.
     bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
     // The above routine returns true if we were able to force the
     // next GC pause to be an initial mark; it returns false if a
     // marking cycle is already in progress.
     //
     // If a marking cycle is already in progress just return and skip
     // the pause - the requesting thread should block in doit_epilogue
     // until the marking cycle is complete.
     if (!res) {
       assert(_word_size == 0, "ExplicitGCInvokesConcurrent shouldn't be allocating");
       return;
     }
   }
   _pause_succeeded =
     g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
   if (_pause_succeeded && _word_size > 0) {
     // An allocation had been requested.
     _result = g1h->attempt_allocation_at_safepoint(_word_size,
                                       true /* expect_null_cur_alloc_region */);
   } else {
     assert(_result == NULL, "invariant");
   }
 }
 void VM_G1IncCollectionPause::doit_epilogue() {
   VM_GC_Operation::doit_epilogue();
   // If the pause was initiated by a System.gc() and
   // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
   // that just started (or maybe one that was already in progress) to
   // finish.
   if (_gc_cause == GCCause::_java_lang_system_gc &&
       _should_initiate_conc_mark) {
     assert(ExplicitGCInvokesConcurrent,
            "the only way to be here is if ExplicitGCInvokesConcurrent is set");
     G1CollectedHeap* g1h = G1CollectedHeap::heap();
     // In the doit() method we saved g1h->full_collections_completed()
     // in the _full_collections_completed_before field. We have to
     // wait until we observe that g1h->full_collections_completed()
     // has increased by at least one. This can happen if a) we started
     // a cycle and it completes, b) a cycle already in progress
     // completes, or c) a Full GC happens.
     // If the condition has already been reached, there's no point in
     // actually taking the lock and doing the wait.
     if (g1h->full_collections_completed() <=
                                           _full_collections_completed_before) {
       // The following is largely copied from CMS
       Thread* thr = Thread::current();
       assert(thr->is_Java_thread(), "invariant");
       JavaThread* jt = (JavaThread*)thr;
       ThreadToNativeFromVM native(jt);
       MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
       while (g1h->full_collections_completed() <=
                                           _full_collections_completed_before) {
         FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
       }
     }
   }
 }
 void VM_CGC_Operation::doit() {
   gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
   TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
   TraceTime t(_printGCMessage, PrintGC, true, gclog_or_tty);
   SharedHeap* sh = SharedHeap::heap();
   // This could go away if CollectedHeap gave access to _gc_is_active...
   if (sh != NULL) {
     IsGCActiveMark x;
     _cl->do_void();
   } else {
     _cl->do_void();
   }
 }
 bool VM_CGC_Operation::doit_prologue() {
   Heap_lock->lock();
   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
   return true;
 }
 void VM_CGC_Operation::doit_epilogue() {
   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
   Heap_lock->unlock();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp@4dfb2df418f2 (annotated)

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp