--- old/src/share/vm/memory/genMarkSweep.cpp 2015-05-12 11:56:13.308233210 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,328 +0,0 @@ -/* - * 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_implementation/shared/gcHeapSummary.hpp" -#include "gc_implementation/shared/gcTimer.hpp" -#include "gc_implementation/shared/gcTrace.hpp" -#include "gc_implementation/shared/gcTraceTime.hpp" -#include "gc_interface/collectedHeap.inline.hpp" -#include "memory/genCollectedHeap.hpp" -#include "memory/genMarkSweep.hpp" -#include "memory/genOopClosures.inline.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/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(int level, ReferenceProcessor* rp, bool clear_all_softrefs) { - guarantee(level == 1, "We always collect both old and young."); - 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"); - _ref_processor = rp; - rp->setup_policy(clear_all_softrefs); - - GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, _gc_tracer->gc_id()); - - 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(level); - - allocate_stacks(); - - mark_sweep_phase1(level, 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(level); - - 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 - _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(int level, - bool clear_all_softrefs) { - // Recursively traverse all live objects and mark them - GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id()); - - 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. - assert(level == 1, "We don't use mark-sweep on young generations"); - follow_root_closure.set_orig_generation(gch->old_gen()); - - // Need new claim bits before marking starts. - ClassLoaderDataGraph::clear_claimed_marks(); - - gch->gen_process_roots(level, - false, // Younger gens are not roots. - true, // activate StrongRootsScope - GenCollectedHeap::SO_None, - GenCollectedHeap::StrongRootsOnly, - &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->gc_id()); - 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, _gc_tracer->gc_id()); - - gch->prepare_for_compaction(); -} - -class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { -public: - void do_generation(Generation* gen) { - gen->adjust_pointers(); - } -}; - -void GenMarkSweep::mark_sweep_phase3(int level) { - GenCollectedHeap* gch = GenCollectedHeap::heap(); - - // Adjust the pointers to reflect the new locations - GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id()); - - // 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. - assert(level == 1, "We don't use mark-sweep on young generations."); - adjust_pointer_closure.set_orig_generation(gch->old_gen()); - - gch->gen_process_roots(level, - false, // Younger gens are not roots. - true, // activate StrongRootsScope - 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, _gc_tracer->gc_id()); - - GenCompactClosure blk; - gch->generation_iterate(&blk, true); -} --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/serial/genMarkSweep.cpp 2015-05-12 11:56:13.115225078 +0200 @@ -0,0 +1,328 @@ +/* + * 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/genOopClosures.inline.hpp" +#include "gc/shared/modRefBarrierSet.hpp" +#include "gc/shared/referencePolicy.hpp" +#include "gc/shared/space.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(int level, ReferenceProcessor* rp, bool clear_all_softrefs) { + guarantee(level == 1, "We always collect both old and young."); + 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"); + _ref_processor = rp; + rp->setup_policy(clear_all_softrefs); + + GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, _gc_tracer->gc_id()); + + 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(level); + + allocate_stacks(); + + mark_sweep_phase1(level, 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(level); + + 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 + _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(int level, + bool clear_all_softrefs) { + // Recursively traverse all live objects and mark them + GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id()); + + 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. + assert(level == 1, "We don't use mark-sweep on young generations"); + follow_root_closure.set_orig_generation(gch->old_gen()); + + // Need new claim bits before marking starts. + ClassLoaderDataGraph::clear_claimed_marks(); + + gch->gen_process_roots(level, + false, // Younger gens are not roots. + true, // activate StrongRootsScope + GenCollectedHeap::SO_None, + GenCollectedHeap::StrongRootsOnly, + &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->gc_id()); + 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, _gc_tracer->gc_id()); + + gch->prepare_for_compaction(); +} + +class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { +public: + void do_generation(Generation* gen) { + gen->adjust_pointers(); + } +}; + +void GenMarkSweep::mark_sweep_phase3(int level) { + GenCollectedHeap* gch = GenCollectedHeap::heap(); + + // Adjust the pointers to reflect the new locations + GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id()); + + // 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. + assert(level == 1, "We don't use mark-sweep on young generations."); + adjust_pointer_closure.set_orig_generation(gch->old_gen()); + + gch->gen_process_roots(level, + false, // Younger gens are not roots. + true, // activate StrongRootsScope + 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, _gc_tracer->gc_id()); + + GenCompactClosure blk; + gch->generation_iterate(&blk, true); +}