| /* |
| * Copyright (c) 2001, 2015, 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/stringTable.hpp" |
| #include "classfile/systemDictionary.hpp" |
| #include "classfile/vmSymbols.hpp" |
| #include "code/codeCache.hpp" |
| #include "code/icBuffer.hpp" |
| #include "gc/serial/genMarkSweep.hpp" |
| #include "gc/shared/collectedHeap.inline.hpp" |
| #include "gc/shared/gcHeapSummary.hpp" |
| #include "gc/shared/gcTimer.hpp" |
| #include "gc/shared/gcTrace.hpp" |
| #include "gc/shared/gcTraceTime.hpp" |
| #include "gc/shared/genCollectedHeap.hpp" |
| #include "gc/shared/generation.hpp" |
| #include "gc/shared/genOopClosures.inline.hpp" |
| #include "gc/shared/modRefBarrierSet.hpp" |
| #include "gc/shared/referencePolicy.hpp" |
| #include "gc/shared/space.hpp" |
| #include "gc/shared/strongRootsScope.hpp" |
| #include "oops/instanceRefKlass.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "prims/jvmtiExport.hpp" |
| #include "runtime/fprofiler.hpp" |
| #include "runtime/handles.inline.hpp" |
| #include "runtime/synchronizer.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/copy.hpp" |
| #include "utilities/events.hpp" |
| #include "utilities/stack.inline.hpp" |
| |
| void GenMarkSweep::invoke_at_safepoint(ReferenceProcessor* rp, bool clear_all_softrefs) { |
| assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); |
| |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| #ifdef ASSERT |
| if (gch->collector_policy()->should_clear_all_soft_refs()) { |
| assert(clear_all_softrefs, "Policy should have been checked earlier"); |
| } |
| #endif |
| |
| // hook up weak ref data so it can be used during Mark-Sweep |
| assert(ref_processor() == NULL, "no stomping"); |
| assert(rp != NULL, "should be non-NULL"); |
| set_ref_processor(rp); |
| rp->setup_policy(clear_all_softrefs); |
| |
| GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL); |
| |
| gch->trace_heap_before_gc(_gc_tracer); |
| |
| // When collecting the permanent generation Method*s may be moving, |
| // so we either have to flush all bcp data or convert it into bci. |
| CodeCache::gc_prologue(); |
| |
| // Increment the invocation count |
| _total_invocations++; |
| |
| // Capture heap size before collection for printing. |
| size_t gch_prev_used = gch->used(); |
| |
| // Capture used regions for each generation that will be |
| // subject to collection, so that card table adjustments can |
| // be made intelligently (see clear / invalidate further below). |
| gch->save_used_regions(); |
| |
| allocate_stacks(); |
| |
| mark_sweep_phase1(clear_all_softrefs); |
| |
| mark_sweep_phase2(); |
| |
| // Don't add any more derived pointers during phase3 |
| COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); |
| COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); |
| |
| mark_sweep_phase3(); |
| |
| mark_sweep_phase4(); |
| |
| restore_marks(); |
| |
| // Set saved marks for allocation profiler (and other things? -- dld) |
| // (Should this be in general part?) |
| gch->save_marks(); |
| |
| deallocate_stacks(); |
| |
| // If compaction completely evacuated the young generation then we |
| // can clear the card table. Otherwise, we must invalidate |
| // it (consider all cards dirty). In the future, we might consider doing |
| // compaction within generations only, and doing card-table sliding. |
| GenRemSet* rs = gch->rem_set(); |
| Generation* old_gen = gch->old_gen(); |
| |
| // Clear/invalidate below make use of the "prev_used_regions" saved earlier. |
| if (gch->young_gen()->used() == 0) { |
| // We've evacuated the young generation. |
| rs->clear_into_younger(old_gen); |
| } else { |
| // Invalidate the cards corresponding to the currently used |
| // region and clear those corresponding to the evacuated region. |
| rs->invalidate_or_clear(old_gen); |
| } |
| |
| CodeCache::gc_epilogue(); |
| JvmtiExport::gc_epilogue(); |
| |
| if (PrintGC && !PrintGCDetails) { |
| gch->print_heap_change(gch_prev_used); |
| } |
| |
| // refs processing: clean slate |
| set_ref_processor(NULL); |
| |
| // Update heap occupancy information which is used as |
| // input to soft ref clearing policy at the next gc. |
| Universe::update_heap_info_at_gc(); |
| |
| // Update time of last gc for all generations we collected |
| // (which currently is all the generations in the heap). |
| // We need to use a monotonically non-decreasing time in ms |
| // or we will see time-warp warnings and os::javaTimeMillis() |
| // does not guarantee monotonicity. |
| jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; |
| gch->update_time_of_last_gc(now); |
| |
| gch->trace_heap_after_gc(_gc_tracer); |
| } |
| |
| void GenMarkSweep::allocate_stacks() { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| // Scratch request on behalf of old generation; will do no allocation. |
| ScratchBlock* scratch = gch->gather_scratch(gch->old_gen(), 0); |
| |
| // $$$ To cut a corner, we'll only use the first scratch block, and then |
| // revert to malloc. |
| if (scratch != NULL) { |
| _preserved_count_max = |
| scratch->num_words * HeapWordSize / sizeof(PreservedMark); |
| } else { |
| _preserved_count_max = 0; |
| } |
| |
| _preserved_marks = (PreservedMark*)scratch; |
| _preserved_count = 0; |
| } |
| |
| |
| void GenMarkSweep::deallocate_stacks() { |
| if (!UseG1GC) { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| gch->release_scratch(); |
| } |
| |
| _preserved_mark_stack.clear(true); |
| _preserved_oop_stack.clear(true); |
| _marking_stack.clear(); |
| _objarray_stack.clear(true); |
| } |
| |
| void GenMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { |
| // Recursively traverse all live objects and mark them |
| GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer); |
| |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| |
| // Because follow_root_closure is created statically, cannot |
| // use OopsInGenClosure constructor which takes a generation, |
| // as the Universe has not been created when the static constructors |
| // are run. |
| follow_root_closure.set_orig_generation(gch->old_gen()); |
| |
| // Need new claim bits before marking starts. |
| ClassLoaderDataGraph::clear_claimed_marks(); |
| |
| { |
| StrongRootsScope srs(1); |
| |
| gch->gen_process_roots(&srs, |
| GenCollectedHeap::OldGen, |
| false, // Younger gens are not roots. |
| GenCollectedHeap::SO_None, |
| ClassUnloading, |
| &follow_root_closure, |
| &follow_root_closure, |
| &follow_cld_closure); |
| } |
| |
| // Process reference objects found during marking |
| { |
| ref_processor()->setup_policy(clear_all_softrefs); |
| const ReferenceProcessorStats& stats = |
| ref_processor()->process_discovered_references( |
| &is_alive, &keep_alive, &follow_stack_closure, NULL, _gc_timer); |
| gc_tracer()->report_gc_reference_stats(stats); |
| } |
| |
| // This is the point where the entire marking should have completed. |
| assert(_marking_stack.is_empty(), "Marking should have completed"); |
| |
| // Unload classes and purge the SystemDictionary. |
| bool purged_class = SystemDictionary::do_unloading(&is_alive); |
| |
| // Unload nmethods. |
| CodeCache::do_unloading(&is_alive, purged_class); |
| |
| // Prune dead klasses from subklass/sibling/implementor lists. |
| Klass::clean_weak_klass_links(&is_alive); |
| |
| // Delete entries for dead interned strings. |
| StringTable::unlink(&is_alive); |
| |
| // Clean up unreferenced symbols in symbol table. |
| SymbolTable::unlink(); |
| |
| gc_tracer()->report_object_count_after_gc(&is_alive); |
| } |
| |
| |
| void GenMarkSweep::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 Klass* 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 Klass*! |
| // |
| // 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. |
| |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| |
| GCTraceTime tm("phase 2", PrintGC && Verbose, true, _gc_timer); |
| |
| gch->prepare_for_compaction(); |
| } |
| |
| class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { |
| public: |
| void do_generation(Generation* gen) { |
| gen->adjust_pointers(); |
| } |
| }; |
| |
| void GenMarkSweep::mark_sweep_phase3() { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| |
| // Adjust the pointers to reflect the new locations |
| GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer); |
| |
| // Need new claim bits for the pointer adjustment tracing. |
| ClassLoaderDataGraph::clear_claimed_marks(); |
| |
| // Because the closure below is created statically, we cannot |
| // use OopsInGenClosure constructor which takes a generation, |
| // as the Universe has not been created when the static constructors |
| // are run. |
| adjust_pointer_closure.set_orig_generation(gch->old_gen()); |
| |
| { |
| StrongRootsScope srs(1); |
| |
| gch->gen_process_roots(&srs, |
| GenCollectedHeap::OldGen, |
| false, // Younger gens are not roots. |
| GenCollectedHeap::SO_AllCodeCache, |
| GenCollectedHeap::StrongAndWeakRoots, |
| &adjust_pointer_closure, |
| &adjust_pointer_closure, |
| &adjust_cld_closure); |
| } |
| |
| gch->gen_process_weak_roots(&adjust_pointer_closure); |
| |
| adjust_marks(); |
| GenAdjustPointersClosure blk; |
| gch->generation_iterate(&blk, true); |
| } |
| |
| class GenCompactClosure: public GenCollectedHeap::GenClosure { |
| public: |
| void do_generation(Generation* gen) { |
| gen->compact(); |
| } |
| }; |
| |
| void GenMarkSweep::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 Klass*s 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. |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| |
| GCTraceTime tm("phase 4", PrintGC && Verbose, true, _gc_timer); |
| |
| GenCompactClosure blk; |
| gch->generation_iterate(&blk, true); |
| } |