ysr@777: /*
pliden@6413:  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
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.
ysr@777:  *
ysr@777:  */
ysr@777: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "classfile/javaClasses.hpp"
stefank@2314: #include "classfile/symbolTable.hpp"
stefank@2314: #include "classfile/systemDictionary.hpp"
stefank@2314: #include "classfile/vmSymbols.hpp"
stefank@2314: #include "code/codeCache.hpp"
stefank@2314: #include "code/icBuffer.hpp"
brutisso@3710: #include "gc_implementation/g1/g1Log.hpp"
stefank@2314: #include "gc_implementation/g1/g1MarkSweep.hpp"
pliden@6413: #include "gc_implementation/g1/g1StringDedup.hpp"
sla@5237: #include "gc_implementation/shared/gcHeapSummary.hpp"
sla@5237: #include "gc_implementation/shared/gcTimer.hpp"
sla@5237: #include "gc_implementation/shared/gcTrace.hpp"
sla@5237: #include "gc_implementation/shared/gcTraceTime.hpp"
stefank@2314: #include "memory/gcLocker.hpp"
stefank@2314: #include "memory/genCollectedHeap.hpp"
stefank@2314: #include "memory/modRefBarrierSet.hpp"
stefank@2314: #include "memory/referencePolicy.hpp"
stefank@2314: #include "memory/space.hpp"
stefank@2314: #include "oops/instanceRefKlass.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
stefank@2314: #include "prims/jvmtiExport.hpp"
stefank@2314: #include "runtime/biasedLocking.hpp"
stefank@2314: #include "runtime/fprofiler.hpp"
stefank@2314: #include "runtime/synchronizer.hpp"
stefank@2314: #include "runtime/thread.hpp"
stefank@2314: #include "runtime/vmThread.hpp"
stefank@2314: #include "utilities/copy.hpp"
stefank@2314: #include "utilities/events.hpp"
ysr@777: 
ysr@777: class HeapRegion;
ysr@777: 
ysr@777: void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
ysr@777:                                       bool clear_all_softrefs) {
ysr@777:   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
ysr@777: 
jmasa@1822:   SharedHeap* sh = SharedHeap::heap();
jmasa@1822: #ifdef ASSERT
jmasa@1822:   if (sh->collector_policy()->should_clear_all_soft_refs()) {
jmasa@1822:     assert(clear_all_softrefs, "Policy should have been checked earler");
jmasa@1822:   }
jmasa@1822: #endif
ysr@777:   // hook up weak ref data so it can be used during Mark-Sweep
ysr@777:   assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
ysr@888:   assert(rp != NULL, "should be non-NULL");
johnc@3175:   assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition");
johnc@3175: 
ysr@777:   GenMarkSweep::_ref_processor = rp;
ysr@892:   rp->setup_policy(clear_all_softrefs);
ysr@777: 
coleenp@4037:   // When collecting the permanent generation Method*s may be moving,
ysr@777:   // so we either have to flush all bcp data or convert it into bci.
ysr@777:   CodeCache::gc_prologue();
ysr@777:   Threads::gc_prologue();
ysr@777: 
ysr@777:   bool marked_for_unloading = false;
ysr@777: 
ysr@777:   allocate_stacks();
ysr@777: 
iveresov@793:   // We should save the marks of the currently locked biased monitors.
iveresov@793:   // The marking doesn't preserve the marks of biased objects.
iveresov@793:   BiasedLocking::preserve_marks();
iveresov@793: 
ysr@777:   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
ysr@777: 
ysr@777:   mark_sweep_phase2();
ysr@777: 
ysr@777:   // Don't add any more derived pointers during phase3
ysr@777:   COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
ysr@777: 
ysr@777:   mark_sweep_phase3();
ysr@777: 
ysr@777:   mark_sweep_phase4();
ysr@777: 
ysr@777:   GenMarkSweep::restore_marks();
iveresov@793:   BiasedLocking::restore_marks();
ysr@777:   GenMarkSweep::deallocate_stacks();
ysr@777: 
ysr@777:   // "free at last gc" is calculated from these.
ysr@777:   // CHF: cheating for now!!!
ysr@777:   //  Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
ysr@777:   //  Universe::set_heap_used_at_last_gc(Universe::heap()->used());
ysr@777: 
ysr@777:   Threads::gc_epilogue();
ysr@777:   CodeCache::gc_epilogue();
kamg@2467:   JvmtiExport::gc_epilogue();
ysr@777: 
ysr@777:   // refs processing: clean slate
ysr@777:   GenMarkSweep::_ref_processor = NULL;
ysr@777: }
ysr@777: 
ysr@777: 
ysr@777: void G1MarkSweep::allocate_stacks() {
ysr@777:   GenMarkSweep::_preserved_count_max = 0;
ysr@777:   GenMarkSweep::_preserved_marks = NULL;
ysr@777:   GenMarkSweep::_preserved_count = 0;
ysr@777: }
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
ysr@777:                                     bool clear_all_softrefs) {
ysr@777:   // Recursively traverse all live objects and mark them
sla@5237:   GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer());
ysr@777:   GenMarkSweep::trace(" 1");
ysr@777: 
ysr@777:   SharedHeap* sh = SharedHeap::heap();
ysr@777: 
coleenp@4037:   // Need cleared claim bits for the strong roots processing
coleenp@4037:   ClassLoaderDataGraph::clear_claimed_marks();
coleenp@4037: 
coleenp@4037:   sh->process_strong_roots(true,  // activate StrongRootsScope
coleenp@4037:                            false, // not scavenging.
ysr@777:                            SharedHeap::SO_SystemClasses,
ysr@777:                            &GenMarkSweep::follow_root_closure,
jrose@1424:                            &GenMarkSweep::follow_code_root_closure,
coleenp@4037:                            &GenMarkSweep::follow_klass_closure);
ysr@777: 
ysr@777:   // Process reference objects found during marking
ysr@888:   ReferenceProcessor* rp = GenMarkSweep::ref_processor();
johnc@3175:   assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Sanity");
johnc@3175: 
ysr@892:   rp->setup_policy(clear_all_softrefs);
sla@5237:   const ReferenceProcessorStats& stats =
sla@5237:     rp->process_discovered_references(&GenMarkSweep::is_alive,
sla@5237:                                       &GenMarkSweep::keep_alive,
sla@5237:                                       &GenMarkSweep::follow_stack_closure,
sla@5237:                                       NULL,
sla@5237:                                       gc_timer());
sla@5237:   gc_tracer()->report_gc_reference_stats(stats);
ysr@777: 
stefank@5020: 
stefank@5020:   // This is the point where the entire marking should have completed.
stefank@5020:   assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
stefank@5020: 
stefank@5020:   // Unload classes and purge the SystemDictionary.
ysr@777:   bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
ysr@777: 
stefank@5020:   // Unload nmethods.
brutisso@4098:   CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class);
ysr@777: 
stefank@5020:   // Prune dead klasses from subklass/sibling/implementor lists.
coleenp@4037:   Klass::clean_weak_klass_links(&GenMarkSweep::is_alive);
ysr@777: 
tschatzl@6229:   // Delete entries for dead interned string and clean up unreferenced symbols in symbol table.
tschatzl@6229:   G1CollectedHeap::heap()->unlink_string_and_symbol_table(&GenMarkSweep::is_alive);
ysr@777: 
johnc@2969:   if (VerifyDuringGC) {
johnc@2969:     HandleMark hm;  // handle scope
johnc@2969:     COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
johnc@2969:     Universe::heap()->prepare_for_verify();
johnc@2969:     // Note: we can verify only the heap here. When an object is
johnc@2969:     // marked, the previous value of the mark word (including
johnc@2969:     // identity hash values, ages, etc) is preserved, and the mark
johnc@2969:     // word is set to markOop::marked_value - effectively removing
johnc@2969:     // any hash values from the mark word. These hash values are
johnc@2969:     // used when verifying the dictionaries and so removing them
johnc@2969:     // from the mark word can make verification of the dictionaries
johnc@2969:     // fail. At the end of the GC, the orginal mark word values
johnc@2969:     // (including hash values) are restored to the appropriate
johnc@2969:     // objects.
stefank@5018:     if (!VerifySilently) {
stefank@5018:       gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
stefank@5018:     }
stefank@5018:     Universe::heap()->verify(VerifySilently, VerifyOption_G1UseMarkWord);
stefank@5018:     if (!VerifySilently) {
stefank@5018:       gclog_or_tty->print_cr("]");
stefank@5018:     }
johnc@2969:   }
sla@5237: 
sla@5237:   gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive);
ysr@777: }
ysr@777: 
ysr@777: class G1PrepareCompactClosure: public HeapRegionClosure {
tonyp@2472:   G1CollectedHeap* _g1h;
ysr@777:   ModRefBarrierSet* _mrbs;
ysr@777:   CompactPoint _cp;
brutisso@6385:   HeapRegionSetCount _humongous_regions_removed;
ysr@777: 
ysr@777:   void free_humongous_region(HeapRegion* hr) {
ysr@777:     HeapWord* end = hr->end();
tonyp@2643:     FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
tonyp@2643: 
ysr@777:     assert(hr->startsHumongous(),
ysr@777:            "Only the start of a humongous region should be freed.");
brutisso@6385: 
brutisso@6385:     hr->set_containing_set(NULL);
brutisso@6385:     _humongous_regions_removed.increment(1u, hr->capacity());
brutisso@6385: 
brutisso@6385:     _g1h->free_humongous_region(hr, &dummy_free_list, false /* par */);
ysr@777:     hr->prepare_for_compaction(&_cp);
ysr@777:     // Also clear the part of the card table that will be unused after
ysr@777:     // compaction.
tonyp@2472:     _mrbs->clear(MemRegion(hr->compaction_top(), end));
tonyp@2643:     dummy_free_list.remove_all();
ysr@777:   }
ysr@777: 
ysr@777: public:
tonyp@2472:   G1PrepareCompactClosure(CompactibleSpace* cs)
tonyp@2472:   : _g1h(G1CollectedHeap::heap()),
mgerdin@5811:     _mrbs(_g1h->g1_barrier_set()),
ysr@777:     _cp(NULL, cs, cs->initialize_threshold()),
brutisso@6385:     _humongous_regions_removed() { }
tonyp@2472: 
tonyp@2472:   void update_sets() {
tonyp@2472:     // We'll recalculate total used bytes and recreate the free list
tonyp@2472:     // at the end of the GC, so no point in updating those values here.
brutisso@6385:     HeapRegionSetCount empty_set;
brutisso@6385:     _g1h->remove_from_old_sets(empty_set, _humongous_regions_removed);
tonyp@2472:   }
tonyp@2472: 
ysr@777:   bool doHeapRegion(HeapRegion* hr) {
ysr@777:     if (hr->isHumongous()) {
ysr@777:       if (hr->startsHumongous()) {
ysr@777:         oop obj = oop(hr->bottom());
ysr@777:         if (obj->is_gc_marked()) {
ysr@777:           obj->forward_to(obj);
ysr@777:         } else  {
ysr@777:           free_humongous_region(hr);
ysr@777:         }
ysr@777:       } else {
ysr@777:         assert(hr->continuesHumongous(), "Invalid humongous.");
ysr@777:       }
ysr@777:     } else {
ysr@777:       hr->prepare_for_compaction(&_cp);
ysr@777:       // Also clear the part of the card table that will be unused after
ysr@777:       // compaction.
ysr@777:       _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
ysr@777:     }
ysr@777:     return false;
ysr@777:   }
ysr@777: };
apetrusenko@1112: 
ysr@777: void G1MarkSweep::mark_sweep_phase2() {
ysr@777:   // Now all live objects are marked, compute the new object addresses.
ysr@777: 
ysr@777:   // It is not required that we traverse spaces in the same order in
ysr@777:   // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
ysr@777:   // tracking expects us to do so. See comment under phase4.
ysr@777: 
ysr@777:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777: 
sla@5237:   GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer());
ysr@777:   GenMarkSweep::trace("2");
ysr@777: 
tonyp@3957:   // find the first region
tonyp@3957:   HeapRegion* r = g1h->region_at(0);
ysr@777:   CompactibleSpace* sp = r;
ysr@777:   if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
ysr@777:     sp = r->next_compaction_space();
ysr@777:   }
ysr@777: 
apetrusenko@1112:   G1PrepareCompactClosure blk(sp);
ysr@777:   g1h->heap_region_iterate(&blk);
tonyp@2472:   blk.update_sets();
ysr@777: }
ysr@777: 
ysr@777: class G1AdjustPointersClosure: public HeapRegionClosure {
ysr@777:  public:
ysr@777:   bool doHeapRegion(HeapRegion* r) {
ysr@777:     if (r->isHumongous()) {
ysr@777:       if (r->startsHumongous()) {
ysr@777:         // We must adjust the pointers on the single H object.
ysr@777:         oop obj = oop(r->bottom());
ysr@777:         // point all the oops to the new location
ysr@777:         obj->adjust_pointers();
ysr@777:       }
ysr@777:     } else {
ysr@777:       // This really ought to be "as_CompactibleSpace"...
ysr@777:       r->adjust_pointers();
ysr@777:     }
ysr@777:     return false;
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase3() {
ysr@777:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777: 
ysr@777:   // Adjust the pointers to reflect the new locations
sla@5237:   GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer());
ysr@777:   GenMarkSweep::trace("3");
ysr@777: 
ysr@777:   SharedHeap* sh = SharedHeap::heap();
ysr@777: 
coleenp@4037:   // Need cleared claim bits for the strong roots processing
coleenp@4037:   ClassLoaderDataGraph::clear_claimed_marks();
coleenp@4037: 
jrose@1424:   sh->process_strong_roots(true,  // activate StrongRootsScope
coleenp@4037:                            false, // not scavenging.
ysr@777:                            SharedHeap::SO_AllClasses,
stefank@5011:                            &GenMarkSweep::adjust_pointer_closure,
jrose@1424:                            NULL,  // do not touch code cache here
coleenp@4037:                            &GenMarkSweep::adjust_klass_closure);
ysr@777: 
johnc@3175:   assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity");
stefank@5011:   g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
ysr@777: 
ysr@777:   // Now adjust pointers in remaining weak roots.  (All of which should
ysr@777:   // have been cleared if they pointed to non-surviving objects.)
stefank@5011:   g1h->g1_process_weak_roots(&GenMarkSweep::adjust_pointer_closure);
ysr@777: 
pliden@6413:   if (G1StringDedup::is_enabled()) {
pliden@6413:     G1StringDedup::oops_do(&GenMarkSweep::adjust_pointer_closure);
pliden@6413:   }
pliden@6413: 
ysr@777:   GenMarkSweep::adjust_marks();
ysr@777: 
ysr@777:   G1AdjustPointersClosure blk;
ysr@777:   g1h->heap_region_iterate(&blk);
ysr@777: }
ysr@777: 
ysr@777: class G1SpaceCompactClosure: public HeapRegionClosure {
ysr@777: public:
ysr@777:   G1SpaceCompactClosure() {}
ysr@777: 
ysr@777:   bool doHeapRegion(HeapRegion* hr) {
ysr@777:     if (hr->isHumongous()) {
ysr@777:       if (hr->startsHumongous()) {
ysr@777:         oop obj = oop(hr->bottom());
ysr@777:         if (obj->is_gc_marked()) {
ysr@777:           obj->init_mark();
ysr@777:         } else {
ysr@777:           assert(hr->is_empty(), "Should have been cleared in phase 2.");
ysr@777:         }
ysr@777:         hr->reset_during_compaction();
ysr@777:       }
ysr@777:     } else {
ysr@777:       hr->compact();
ysr@777:     }
ysr@777:     return false;
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase4() {
ysr@777:   // All pointers are now adjusted, move objects accordingly
ysr@777: 
ysr@777:   // The ValidateMarkSweep live oops tracking expects us to traverse spaces
ysr@777:   // in the same order in phase2, phase3 and phase4. We don't quite do that
coleenp@4037:   // here (code and comment not fixed for perm removal), so we tell the validate code
ysr@777:   // to use a higher index (saved from phase2) when verifying perm_gen.
ysr@777:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777: 
sla@5237:   GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer());
ysr@777:   GenMarkSweep::trace("4");
ysr@777: 
ysr@777:   G1SpaceCompactClosure blk;
ysr@777:   g1h->heap_region_iterate(&blk);
ysr@777: 
ysr@777: }