| /* |
| * 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_interface/collectedHeap.inline.hpp" |
| #include "memory/genCollectedHeap.hpp" |
| #include "memory/genMarkSweep.hpp" |
| #include "memory/genOopClosures.inline.hpp" |
| #include "memory/generation.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/vmThread.hpp" |
| #include "utilities/copy.hpp" |
| #include "utilities/events.hpp" |
| #ifdef TARGET_OS_FAMILY_linux |
| # include "thread_linux.inline.hpp" |
| #endif |
| #ifdef TARGET_OS_FAMILY_solaris |
| # include "thread_solaris.inline.hpp" |
| #endif |
| #ifdef TARGET_OS_FAMILY_windows |
| # include "thread_windows.inline.hpp" |
| #endif |
| #ifdef TARGET_OS_FAMILY_bsd |
| # include "thread_bsd.inline.hpp" |
| #endif |
| |
| void GenMarkSweep::invoke_at_safepoint(int level, 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"); |
| _ref_processor = rp; |
| rp->setup_policy(clear_all_softrefs); |
| |
| TraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, gclog_or_tty); |
| |
| // 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. |
| gch->perm_gen()->stat_record()->invocations++; |
| |
| // Capture heap size before collection for printing. |
| size_t gch_prev_used = gch->used(); |
| |
| // Some of the card table updates below assume that the perm gen is |
| // also being collected. |
| assert(level == gch->n_gens() - 1, |
| "All generations are being collected, ergo perm gen too."); |
| |
| // 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, true /* perm */); |
| |
| 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); |
| |
| VALIDATE_MARK_SWEEP_ONLY( |
| if (ValidateMarkSweep) { |
| guarantee(_root_refs_stack->length() == 0, "should be empty by now"); |
| } |
| ) |
| |
| mark_sweep_phase4(); |
| |
| VALIDATE_MARK_SWEEP_ONLY( |
| if (ValidateMarkSweep) { |
| guarantee(_live_oops->length() == _live_oops_moved_to->length(), |
| "should be the same size"); |
| } |
| ) |
| |
| 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 all generations younger than this |
| // one, 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. |
| bool all_empty = true; |
| for (int i = 0; all_empty && i < level; i++) { |
| Generation* g = gch->get_gen(i); |
| all_empty = all_empty && gch->get_gen(i)->used() == 0; |
| } |
| GenRemSet* rs = gch->rem_set(); |
| // Clear/invalidate below make use of the "prev_used_regions" saved earlier. |
| if (all_empty) { |
| // We've evacuated all generations below us. |
| Generation* g = gch->get_gen(level); |
| rs->clear_into_younger(g, true /* perm */); |
| } else { |
| // Invalidate the cards corresponding to the currently used |
| // region and clear those corresponding to the evacuated region |
| // of all generations just collected (i.e. level and younger). |
| rs->invalidate_or_clear(gch->get_gen(level), |
| true /* younger */, |
| true /* perm */); |
| } |
| |
| Threads::gc_epilogue(); |
| 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 curently is all the generations in the heap). |
| // We need to use a monotonically non-deccreasing 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); |
| } |
| |
| void GenMarkSweep::allocate_stacks() { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| // Scratch request on behalf of oldest generation; will do no |
| // allocation. |
| ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 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; |
| |
| #ifdef VALIDATE_MARK_SWEEP |
| if (ValidateMarkSweep) { |
| _root_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
| _other_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
| _adjusted_pointers = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
| _live_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); |
| _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); |
| _live_oops_size = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); |
| } |
| if (RecordMarkSweepCompaction) { |
| if (_cur_gc_live_oops == NULL) { |
| _cur_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
| _cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
| _cur_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); |
| _last_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
| _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
| _last_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); |
| } else { |
| _cur_gc_live_oops->clear(); |
| _cur_gc_live_oops_moved_to->clear(); |
| _cur_gc_live_oops_size->clear(); |
| } |
| } |
| #endif |
| } |
| |
| |
| 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); |
| _revisit_klass_stack.clear(true); |
| _revisit_mdo_stack.clear(true); |
| |
| #ifdef VALIDATE_MARK_SWEEP |
| if (ValidateMarkSweep) { |
| delete _root_refs_stack; |
| delete _other_refs_stack; |
| delete _adjusted_pointers; |
| delete _live_oops; |
| delete _live_oops_size; |
| delete _live_oops_moved_to; |
| _live_oops_index = 0; |
| _live_oops_index_at_perm = 0; |
| } |
| #endif |
| } |
| |
| void GenMarkSweep::mark_sweep_phase1(int level, |
| bool clear_all_softrefs) { |
| // Recursively traverse all live objects and mark them |
| TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty); |
| trace(" 1"); |
| |
| VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
| |
| 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->get_gen(level)); |
| |
| gch->gen_process_strong_roots(level, |
| false, // Younger gens are not roots. |
| true, // activate StrongRootsScope |
| true, // Collecting permanent generation. |
| SharedHeap::SO_SystemClasses, |
| &follow_root_closure, |
| true, // walk code active on stacks |
| &follow_root_closure); |
| |
| // Process reference objects found during marking |
| { |
| ref_processor()->setup_policy(clear_all_softrefs); |
| ref_processor()->process_discovered_references( |
| &is_alive, &keep_alive, &follow_stack_closure, NULL); |
| } |
| |
| // Follow system dictionary roots and unload classes |
| bool purged_class = SystemDictionary::do_unloading(&is_alive); |
| |
| // Follow code cache roots |
| CodeCache::do_unloading(&is_alive, &keep_alive, purged_class); |
| follow_stack(); // Flush marking stack |
| |
| // Update subklass/sibling/implementor links of live klasses |
| follow_weak_klass_links(); |
| assert(_marking_stack.is_empty(), "just drained"); |
| |
| // Visit memoized MDO's and clear any unmarked weak refs |
| follow_mdo_weak_refs(); |
| assert(_marking_stack.is_empty(), "just drained"); |
| |
| // Visit interned string tables and delete unmarked oops |
| StringTable::unlink(&is_alive); |
| // Clean up unreferenced symbols in symbol table. |
| SymbolTable::unlink(); |
| |
| assert(_marking_stack.is_empty(), "stack should be empty by now"); |
| } |
| |
| |
| 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 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. |
| |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| Generation* pg = gch->perm_gen(); |
| |
| TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty); |
| trace("2"); |
| |
| VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
| |
| gch->prepare_for_compaction(); |
| |
| VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index); |
| CompactPoint perm_cp(pg, NULL, NULL); |
| pg->prepare_for_compaction(&perm_cp); |
| } |
| |
| 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(); |
| Generation* pg = gch->perm_gen(); |
| |
| // Adjust the pointers to reflect the new locations |
| TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty); |
| trace("3"); |
| |
| VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
| |
| // Needs to be done before the system dictionary is adjusted. |
| pg->pre_adjust_pointers(); |
| |
| // Because the two closures below are created statically, cannot |
| // use OopsInGenClosure constructor which takes a generation, |
| // as the Universe has not been created when the static constructors |
| // are run. |
| adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level)); |
| adjust_pointer_closure.set_orig_generation(gch->get_gen(level)); |
| |
| gch->gen_process_strong_roots(level, |
| false, // Younger gens are not roots. |
| true, // activate StrongRootsScope |
| true, // Collecting permanent generation. |
| SharedHeap::SO_AllClasses, |
| &adjust_root_pointer_closure, |
| false, // do not walk code |
| &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.) |
| CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure, |
| /*do_marking=*/ false); |
| gch->gen_process_weak_roots(&adjust_root_pointer_closure, |
| &adjust_code_pointer_closure, |
| &adjust_pointer_closure); |
| |
| adjust_marks(); |
| GenAdjustPointersClosure blk; |
| gch->generation_iterate(&blk, true); |
| pg->adjust_pointers(); |
| } |
| |
| 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 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. |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| Generation* pg = gch->perm_gen(); |
| |
| TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty); |
| trace("4"); |
| |
| VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true)); |
| |
| pg->compact(); |
| |
| VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
| |
| GenCompactClosure blk; |
| gch->generation_iterate(&blk, true); |
| |
| VALIDATE_MARK_SWEEP_ONLY(compaction_complete()); |
| |
| pg->post_compact(); // Shared spaces verification. |
| } |