| /* |
| * Copyright (c) 2001, 2012, 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 |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "classfile/javaClasses.hpp" |
| #include "classfile/symbolTable.hpp" |
| #include "classfile/systemDictionary.hpp" |
| #include "classfile/vmSymbols.hpp" |
| #include "code/codeCache.hpp" |
| #include "code/icBuffer.hpp" |
| #include "gc_implementation/g1/g1Log.hpp" |
| #include "gc_implementation/g1/g1MarkSweep.hpp" |
| #include "gc_implementation/shared/gcHeapSummary.hpp" |
| #include "gc_implementation/shared/gcTimer.hpp" |
| #include "gc_implementation/shared/gcTrace.hpp" |
| #include "gc_implementation/shared/gcTraceTime.hpp" |
| #include "memory/gcLocker.hpp" |
| #include "memory/genCollectedHeap.hpp" |
| #include "memory/modRefBarrierSet.hpp" |
| #include "memory/referencePolicy.hpp" |
| #include "memory/space.hpp" |
| #include "oops/instanceRefKlass.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "prims/jvmtiExport.hpp" |
| #include "runtime/aprofiler.hpp" |
| #include "runtime/biasedLocking.hpp" |
| #include "runtime/fprofiler.hpp" |
| #include "runtime/synchronizer.hpp" |
| #include "runtime/thread.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/copy.hpp" |
| #include "utilities/events.hpp" |
| |
| class HeapRegion; |
| |
| void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp, |
| bool clear_all_softrefs) { |
| assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); |
| |
| SharedHeap* sh = SharedHeap::heap(); |
| #ifdef ASSERT |
| if (sh->collector_policy()->should_clear_all_soft_refs()) { |
| assert(clear_all_softrefs, "Policy should have been checked earler"); |
| } |
| #endif |
| // hook up weak ref data so it can be used during Mark-Sweep |
| assert(GenMarkSweep::ref_processor() == NULL, "no stomping"); |
| assert(rp != NULL, "should be non-NULL"); |
| assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition"); |
| |
| GenMarkSweep::_ref_processor = rp; |
| rp->setup_policy(clear_all_softrefs); |
| |
| // When collecting the permanent generation methodOops may be moving, |
| // so we either have to flush all bcp data or convert it into bci. |
| CodeCache::gc_prologue(); |
| Threads::gc_prologue(); |
| |
| // Increment the invocation count for the permanent generation, since it is |
| // implicitly collected whenever we do a full mark sweep collection. |
| sh->perm_gen()->stat_record()->invocations++; |
| |
| bool marked_for_unloading = false; |
| |
| allocate_stacks(); |
| |
| // We should save the marks of the currently locked biased monitors. |
| // The marking doesn't preserve the marks of biased objects. |
| BiasedLocking::preserve_marks(); |
| |
| mark_sweep_phase1(marked_for_unloading, clear_all_softrefs); |
| |
| mark_sweep_phase2(); |
| |
| // Don't add any more derived pointers during phase3 |
| COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); |
| |
| mark_sweep_phase3(); |
| |
| mark_sweep_phase4(); |
| |
| GenMarkSweep::restore_marks(); |
| BiasedLocking::restore_marks(); |
| GenMarkSweep::deallocate_stacks(); |
| |
| // We must invalidate the perm-gen rs, so that it gets rebuilt. |
| GenRemSet* rs = sh->rem_set(); |
| rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/); |
| |
| // "free at last gc" is calculated from these. |
| // CHF: cheating for now!!! |
| // Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity()); |
| // Universe::set_heap_used_at_last_gc(Universe::heap()->used()); |
| |
| Threads::gc_epilogue(); |
| CodeCache::gc_epilogue(); |
| JvmtiExport::gc_epilogue(); |
| |
| // refs processing: clean slate |
| GenMarkSweep::_ref_processor = NULL; |
| } |
| |
| |
| void G1MarkSweep::allocate_stacks() { |
| GenMarkSweep::_preserved_count_max = 0; |
| GenMarkSweep::_preserved_marks = NULL; |
| GenMarkSweep::_preserved_count = 0; |
| } |
| |
| void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading, |
| bool clear_all_softrefs) { |
| // Recursively traverse all live objects and mark them |
| GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer()); |
| GenMarkSweep::trace(" 1"); |
| |
| SharedHeap* sh = SharedHeap::heap(); |
| |
| sh->process_strong_roots(true, // activeate StrongRootsScope |
| true, // Collecting permanent generation. |
| SharedHeap::SO_SystemClasses, |
| &GenMarkSweep::follow_root_closure, |
| &GenMarkSweep::follow_code_root_closure, |
| &GenMarkSweep::follow_root_closure); |
| |
| // Process reference objects found during marking |
| ReferenceProcessor* rp = GenMarkSweep::ref_processor(); |
| assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Sanity"); |
| |
| rp->setup_policy(clear_all_softrefs); |
| const ReferenceProcessorStats& stats = |
| rp->process_discovered_references(&GenMarkSweep::is_alive, |
| &GenMarkSweep::keep_alive, |
| &GenMarkSweep::follow_stack_closure, |
| NULL, |
| gc_timer()); |
| gc_tracer()->report_gc_reference_stats(stats); |
| |
| // Follow system dictionary roots and unload classes |
| bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive); |
| assert(GenMarkSweep::_marking_stack.is_empty(), |
| "stack should be empty by now"); |
| |
| // Follow code cache roots (has to be done after system dictionary, |
| // assumes all live klasses are marked) |
| CodeCache::do_unloading(&GenMarkSweep::is_alive, |
| &GenMarkSweep::keep_alive, |
| purged_class); |
| GenMarkSweep::follow_stack(); |
| |
| // Update subklass/sibling/implementor links of live klasses |
| GenMarkSweep::follow_weak_klass_links(); |
| assert(GenMarkSweep::_marking_stack.is_empty(), |
| "stack should be empty by now"); |
| |
| // Visit memoized MDO's and clear any unmarked weak refs |
| GenMarkSweep::follow_mdo_weak_refs(); |
| assert(GenMarkSweep::_marking_stack.is_empty(), "just drained"); |
| |
| // Visit interned string tables and delete unmarked oops |
| StringTable::unlink(&GenMarkSweep::is_alive); |
| // Clean up unreferenced symbols in symbol table. |
| SymbolTable::unlink(); |
| |
| assert(GenMarkSweep::_marking_stack.is_empty(), |
| "stack should be empty by now"); |
| |
| if (VerifyDuringGC) { |
| HandleMark hm; // handle scope |
| COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); |
| gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying "); |
| Universe::heap()->prepare_for_verify(); |
| // Note: we can verify only the heap here. When an object is |
| // marked, the previous value of the mark word (including |
| // identity hash values, ages, etc) is preserved, and the mark |
| // word is set to markOop::marked_value - effectively removing |
| // any hash values from the mark word. These hash values are |
| // used when verifying the dictionaries and so removing them |
| // from the mark word can make verification of the dictionaries |
| // fail. At the end of the GC, the orginal mark word values |
| // (including hash values) are restored to the appropriate |
| // objects. |
| Universe::heap()->verify(/* silent */ false, |
| /* option */ VerifyOption_G1UseMarkWord); |
| |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| gclog_or_tty->print_cr("]"); |
| } |
| } |
| |
| class G1PrepareCompactClosure: public HeapRegionClosure { |
| G1CollectedHeap* _g1h; |
| ModRefBarrierSet* _mrbs; |
| CompactPoint _cp; |
| HumongousRegionSet _humongous_proxy_set; |
| |
| void free_humongous_region(HeapRegion* hr) { |
| HeapWord* end = hr->end(); |
| size_t dummy_pre_used; |
| FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep"); |
| |
| assert(hr->startsHumongous(), |
| "Only the start of a humongous region should be freed."); |
| _g1h->free_humongous_region(hr, &dummy_pre_used, &dummy_free_list, |
| &_humongous_proxy_set, false /* par */); |
| hr->prepare_for_compaction(&_cp); |
| // Also clear the part of the card table that will be unused after |
| // compaction. |
| _mrbs->clear(MemRegion(hr->compaction_top(), end)); |
| dummy_free_list.remove_all(); |
| } |
| |
| public: |
| G1PrepareCompactClosure(CompactibleSpace* cs) |
| : _g1h(G1CollectedHeap::heap()), |
| _mrbs(G1CollectedHeap::heap()->mr_bs()), |
| _cp(NULL, cs, cs->initialize_threshold()), |
| _humongous_proxy_set("G1MarkSweep Humongous Proxy Set") { } |
| |
| void update_sets() { |
| // We'll recalculate total used bytes and recreate the free list |
| // at the end of the GC, so no point in updating those values here. |
| _g1h->update_sets_after_freeing_regions(0, /* pre_used */ |
| NULL, /* free_list */ |
| NULL, /* old_proxy_set */ |
| &_humongous_proxy_set, |
| false /* par */); |
| } |
| |
| bool doHeapRegion(HeapRegion* hr) { |
| if (hr->isHumongous()) { |
| if (hr->startsHumongous()) { |
| oop obj = oop(hr->bottom()); |
| if (obj->is_gc_marked()) { |
| obj->forward_to(obj); |
| } else { |
| free_humongous_region(hr); |
| } |
| } else { |
| assert(hr->continuesHumongous(), "Invalid humongous."); |
| } |
| } else { |
| hr->prepare_for_compaction(&_cp); |
| // Also clear the part of the card table that will be unused after |
| // compaction. |
| _mrbs->clear(MemRegion(hr->compaction_top(), hr->end())); |
| } |
| return false; |
| } |
| }; |
| |
| void G1MarkSweep::mark_sweep_phase2() { |
| // Now all live objects are marked, compute the new object addresses. |
| |
| // It is imperative that we traverse perm_gen LAST. If dead space is |
| // allowed a range of dead object may get overwritten by a dead int |
| // array. If perm_gen is not traversed last a klassOop may get |
| // overwritten. This is fine since it is dead, but if the class has dead |
| // instances we have to skip them, and in order to find their size we |
| // need the klassOop! |
| // |
| // It is not required that we traverse spaces in the same order in |
| // phase2, phase3 and phase4, but the ValidateMarkSweep live oops |
| // tracking expects us to do so. See comment under phase4. |
| |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| Generation* pg = g1h->perm_gen(); |
| |
| GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer()); |
| GenMarkSweep::trace("2"); |
| |
| // find the first region |
| HeapRegion* r = g1h->region_at(0); |
| CompactibleSpace* sp = r; |
| if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) { |
| sp = r->next_compaction_space(); |
| } |
| |
| G1PrepareCompactClosure blk(sp); |
| g1h->heap_region_iterate(&blk); |
| blk.update_sets(); |
| |
| CompactPoint perm_cp(pg, NULL, NULL); |
| pg->prepare_for_compaction(&perm_cp); |
| } |
| |
| class G1AdjustPointersClosure: public HeapRegionClosure { |
| public: |
| bool doHeapRegion(HeapRegion* r) { |
| if (r->isHumongous()) { |
| if (r->startsHumongous()) { |
| // We must adjust the pointers on the single H object. |
| oop obj = oop(r->bottom()); |
| debug_only(GenMarkSweep::track_interior_pointers(obj)); |
| // point all the oops to the new location |
| obj->adjust_pointers(); |
| debug_only(GenMarkSweep::check_interior_pointers()); |
| } |
| } else { |
| // This really ought to be "as_CompactibleSpace"... |
| r->adjust_pointers(); |
| } |
| return false; |
| } |
| }; |
| |
| void G1MarkSweep::mark_sweep_phase3() { |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| Generation* pg = g1h->perm_gen(); |
| |
| // Adjust the pointers to reflect the new locations |
| GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer()); |
| GenMarkSweep::trace("3"); |
| |
| SharedHeap* sh = SharedHeap::heap(); |
| |
| sh->process_strong_roots(true, // activate StrongRootsScope |
| true, // Collecting permanent generation. |
| SharedHeap::SO_AllClasses, |
| &GenMarkSweep::adjust_root_pointer_closure, |
| NULL, // do not touch code cache here |
| &GenMarkSweep::adjust_pointer_closure); |
| |
| assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity"); |
| g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_root_pointer_closure); |
| |
| // Now adjust pointers in remaining weak roots. (All of which should |
| // have been cleared if they pointed to non-surviving objects.) |
| g1h->g1_process_weak_roots(&GenMarkSweep::adjust_root_pointer_closure, |
| &GenMarkSweep::adjust_pointer_closure); |
| |
| GenMarkSweep::adjust_marks(); |
| |
| G1AdjustPointersClosure blk; |
| g1h->heap_region_iterate(&blk); |
| pg->adjust_pointers(); |
| } |
| |
| class G1SpaceCompactClosure: public HeapRegionClosure { |
| public: |
| G1SpaceCompactClosure() {} |
| |
| bool doHeapRegion(HeapRegion* hr) { |
| if (hr->isHumongous()) { |
| if (hr->startsHumongous()) { |
| oop obj = oop(hr->bottom()); |
| if (obj->is_gc_marked()) { |
| obj->init_mark(); |
| } else { |
| assert(hr->is_empty(), "Should have been cleared in phase 2."); |
| } |
| hr->reset_during_compaction(); |
| } |
| } else { |
| hr->compact(); |
| } |
| return false; |
| } |
| }; |
| |
| void G1MarkSweep::mark_sweep_phase4() { |
| // All pointers are now adjusted, move objects accordingly |
| |
| // It is imperative that we traverse perm_gen first in phase4. All |
| // classes must be allocated earlier than their instances, and traversing |
| // perm_gen first makes sure that all klassOops have moved to their new |
| // location before any instance does a dispatch through it's klass! |
| |
| // The ValidateMarkSweep live oops tracking expects us to traverse spaces |
| // in the same order in phase2, phase3 and phase4. We don't quite do that |
| // here (perm_gen first rather than last), so we tell the validate code |
| // to use a higher index (saved from phase2) when verifying perm_gen. |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| Generation* pg = g1h->perm_gen(); |
| |
| GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer()); |
| GenMarkSweep::trace("4"); |
| |
| pg->compact(); |
| |
| G1SpaceCompactClosure blk; |
| g1h->heap_region_iterate(&blk); |
| |
| } |