| /* |
| * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| # include "incls/_precompiled.incl" |
| # include "incls/_parNewGeneration.cpp.incl" |
| |
| #ifdef _MSC_VER |
| #pragma warning( push ) |
| #pragma warning( disable:4355 ) // 'this' : used in base member initializer list |
| #endif |
| ParScanThreadState::ParScanThreadState(Space* to_space_, |
| ParNewGeneration* gen_, |
| Generation* old_gen_, |
| int thread_num_, |
| ObjToScanQueueSet* work_queue_set_, |
| size_t desired_plab_sz_, |
| ParallelTaskTerminator& term_) : |
| _to_space(to_space_), _old_gen(old_gen_), _thread_num(thread_num_), |
| _work_queue(work_queue_set_->queue(thread_num_)), _to_space_full(false), |
| _ageTable(false), // false ==> not the global age table, no perf data. |
| _to_space_alloc_buffer(desired_plab_sz_), |
| _to_space_closure(gen_, this), _old_gen_closure(gen_, this), |
| _to_space_root_closure(gen_, this), _old_gen_root_closure(gen_, this), |
| _older_gen_closure(gen_, this), |
| _evacuate_followers(this, &_to_space_closure, &_old_gen_closure, |
| &_to_space_root_closure, gen_, &_old_gen_root_closure, |
| work_queue_set_, &term_), |
| _is_alive_closure(gen_), _scan_weak_ref_closure(gen_, this), |
| _keep_alive_closure(&_scan_weak_ref_closure), |
| _pushes(0), _pops(0), _steals(0), _steal_attempts(0), _term_attempts(0), |
| _strong_roots_time(0.0), _term_time(0.0) |
| { |
| _survivor_chunk_array = |
| (ChunkArray*) old_gen()->get_data_recorder(thread_num()); |
| _hash_seed = 17; // Might want to take time-based random value. |
| _start = os::elapsedTime(); |
| _old_gen_closure.set_generation(old_gen_); |
| _old_gen_root_closure.set_generation(old_gen_); |
| } |
| #ifdef _MSC_VER |
| #pragma warning( pop ) |
| #endif |
| |
| void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, |
| size_t plab_word_size) { |
| ChunkArray* sca = survivor_chunk_array(); |
| if (sca != NULL) { |
| // A non-null SCA implies that we want the PLAB data recorded. |
| sca->record_sample(plab_start, plab_word_size); |
| } |
| } |
| |
| bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { |
| return new_obj->is_objArray() && |
| arrayOop(new_obj)->length() > ParGCArrayScanChunk && |
| new_obj != old_obj; |
| } |
| |
| void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { |
| assert(old->is_objArray(), "must be obj array"); |
| assert(old->is_forwarded(), "must be forwarded"); |
| assert(Universe::heap()->is_in_reserved(old), "must be in heap."); |
| assert(!_old_gen->is_in(old), "must be in young generation."); |
| |
| objArrayOop obj = objArrayOop(old->forwardee()); |
| // Process ParGCArrayScanChunk elements now |
| // and push the remainder back onto queue |
| int start = arrayOop(old)->length(); |
| int end = obj->length(); |
| int remainder = end - start; |
| assert(start <= end, "just checking"); |
| if (remainder > 2 * ParGCArrayScanChunk) { |
| // Test above combines last partial chunk with a full chunk |
| end = start + ParGCArrayScanChunk; |
| arrayOop(old)->set_length(end); |
| // Push remainder. |
| bool ok = work_queue()->push(old); |
| assert(ok, "just popped, push must be okay"); |
| note_push(); |
| } else { |
| // Restore length so that it can be used if there |
| // is a promotion failure and forwarding pointers |
| // must be removed. |
| arrayOop(old)->set_length(end); |
| } |
| // process our set of indices (include header in first chunk) |
| oop* start_addr = start == 0 ? (oop*)obj : obj->obj_at_addr(start); |
| oop* end_addr = obj->base() + end; // obj_at_addr(end) asserts end < length |
| MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr); |
| if ((HeapWord *)obj < young_old_boundary()) { |
| // object is in to_space |
| obj->oop_iterate(&_to_space_closure, mr); |
| } else { |
| // object is in old generation |
| obj->oop_iterate(&_old_gen_closure, mr); |
| } |
| } |
| |
| |
| void ParScanThreadState::trim_queues(int max_size) { |
| ObjToScanQueue* queue = work_queue(); |
| while (queue->size() > (juint)max_size) { |
| oop obj_to_scan; |
| if (queue->pop_local(obj_to_scan)) { |
| note_pop(); |
| |
| if ((HeapWord *)obj_to_scan < young_old_boundary()) { |
| if (obj_to_scan->is_objArray() && |
| obj_to_scan->is_forwarded() && |
| obj_to_scan->forwardee() != obj_to_scan) { |
| scan_partial_array_and_push_remainder(obj_to_scan); |
| } else { |
| // object is in to_space |
| obj_to_scan->oop_iterate(&_to_space_closure); |
| } |
| } else { |
| // object is in old generation |
| obj_to_scan->oop_iterate(&_old_gen_closure); |
| } |
| } |
| } |
| } |
| |
| HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { |
| |
| // Otherwise, if the object is small enough, try to reallocate the |
| // buffer. |
| HeapWord* obj = NULL; |
| if (!_to_space_full) { |
| ParGCAllocBuffer* const plab = to_space_alloc_buffer(); |
| Space* const sp = to_space(); |
| if (word_sz * 100 < |
| ParallelGCBufferWastePct * plab->word_sz()) { |
| // Is small enough; abandon this buffer and start a new one. |
| plab->retire(false, false); |
| size_t buf_size = plab->word_sz(); |
| HeapWord* buf_space = sp->par_allocate(buf_size); |
| if (buf_space == NULL) { |
| const size_t min_bytes = |
| ParGCAllocBuffer::min_size() << LogHeapWordSize; |
| size_t free_bytes = sp->free(); |
| while(buf_space == NULL && free_bytes >= min_bytes) { |
| buf_size = free_bytes >> LogHeapWordSize; |
| assert(buf_size == (size_t)align_object_size(buf_size), |
| "Invariant"); |
| buf_space = sp->par_allocate(buf_size); |
| free_bytes = sp->free(); |
| } |
| } |
| if (buf_space != NULL) { |
| plab->set_word_size(buf_size); |
| plab->set_buf(buf_space); |
| record_survivor_plab(buf_space, buf_size); |
| obj = plab->allocate(word_sz); |
| // Note that we cannot compare buf_size < word_sz below |
| // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). |
| assert(obj != NULL || plab->words_remaining() < word_sz, |
| "Else should have been able to allocate"); |
| // It's conceivable that we may be able to use the |
| // buffer we just grabbed for subsequent small requests |
| // even if not for this one. |
| } else { |
| // We're used up. |
| _to_space_full = true; |
| } |
| |
| } else { |
| // Too large; allocate the object individually. |
| obj = sp->par_allocate(word_sz); |
| } |
| } |
| return obj; |
| } |
| |
| |
| void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, |
| size_t word_sz) { |
| // Is the alloc in the current alloc buffer? |
| if (to_space_alloc_buffer()->contains(obj)) { |
| assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), |
| "Should contain whole object."); |
| to_space_alloc_buffer()->undo_allocation(obj, word_sz); |
| } else { |
| SharedHeap::fill_region_with_object(MemRegion(obj, word_sz)); |
| } |
| } |
| |
| class ParScanThreadStateSet: private ResourceArray { |
| public: |
| // Initializes states for the specified number of threads; |
| ParScanThreadStateSet(int num_threads, |
| Space& to_space, |
| ParNewGeneration& gen, |
| Generation& old_gen, |
| ObjToScanQueueSet& queue_set, |
| size_t desired_plab_sz, |
| ParallelTaskTerminator& term); |
| inline ParScanThreadState& thread_sate(int i); |
| int pushes() { return _pushes; } |
| int pops() { return _pops; } |
| int steals() { return _steals; } |
| void reset(); |
| void flush(); |
| private: |
| ParallelTaskTerminator& _term; |
| ParNewGeneration& _gen; |
| Generation& _next_gen; |
| // staticstics |
| int _pushes; |
| int _pops; |
| int _steals; |
| }; |
| |
| |
| ParScanThreadStateSet::ParScanThreadStateSet( |
| int num_threads, Space& to_space, ParNewGeneration& gen, |
| Generation& old_gen, ObjToScanQueueSet& queue_set, |
| size_t desired_plab_sz, ParallelTaskTerminator& term) |
| : ResourceArray(sizeof(ParScanThreadState), num_threads), |
| _gen(gen), _next_gen(old_gen), _term(term), |
| _pushes(0), _pops(0), _steals(0) |
| { |
| assert(num_threads > 0, "sanity check!"); |
| // Initialize states. |
| for (int i = 0; i < num_threads; ++i) { |
| new ((ParScanThreadState*)_data + i) |
| ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, |
| desired_plab_sz, term); |
| } |
| } |
| |
| inline ParScanThreadState& ParScanThreadStateSet::thread_sate(int i) |
| { |
| assert(i >= 0 && i < length(), "sanity check!"); |
| return ((ParScanThreadState*)_data)[i]; |
| } |
| |
| |
| void ParScanThreadStateSet::reset() |
| { |
| _term.reset_for_reuse(); |
| } |
| |
| void ParScanThreadStateSet::flush() |
| { |
| for (int i = 0; i < length(); ++i) { |
| ParScanThreadState& par_scan_state = thread_sate(i); |
| |
| // Flush stats related to To-space PLAB activity and |
| // retire the last buffer. |
| par_scan_state.to_space_alloc_buffer()-> |
| flush_stats_and_retire(_gen.plab_stats(), |
| false /* !retain */); |
| |
| // Every thread has its own age table. We need to merge |
| // them all into one. |
| ageTable *local_table = par_scan_state.age_table(); |
| _gen.age_table()->merge(local_table); |
| |
| // Inform old gen that we're done. |
| _next_gen.par_promote_alloc_done(i); |
| _next_gen.par_oop_since_save_marks_iterate_done(i); |
| |
| // Flush stats related to work queue activity (push/pop/steal) |
| // This could conceivably become a bottleneck; if so, we'll put the |
| // stat's gathering under the flag. |
| if (PAR_STATS_ENABLED) { |
| _pushes += par_scan_state.pushes(); |
| _pops += par_scan_state.pops(); |
| _steals += par_scan_state.steals(); |
| if (ParallelGCVerbose) { |
| gclog_or_tty->print("Thread %d complete:\n" |
| " Pushes: %7d Pops: %7d Steals %7d (in %d attempts)\n", |
| i, par_scan_state.pushes(), par_scan_state.pops(), |
| par_scan_state.steals(), par_scan_state.steal_attempts()); |
| if (par_scan_state.overflow_pushes() > 0 || |
| par_scan_state.overflow_refills() > 0) { |
| gclog_or_tty->print(" Overflow pushes: %7d " |
| "Overflow refills: %7d for %d objs.\n", |
| par_scan_state.overflow_pushes(), |
| par_scan_state.overflow_refills(), |
| par_scan_state.overflow_refill_objs()); |
| } |
| |
| double elapsed = par_scan_state.elapsed(); |
| double strong_roots = par_scan_state.strong_roots_time(); |
| double term = par_scan_state.term_time(); |
| gclog_or_tty->print( |
| " Elapsed: %7.2f ms.\n" |
| " Strong roots: %7.2f ms (%6.2f%%)\n" |
| " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n", |
| elapsed * 1000.0, |
| strong_roots * 1000.0, (strong_roots*100.0/elapsed), |
| term * 1000.0, (term*100.0/elapsed), |
| par_scan_state.term_attempts()); |
| } |
| } |
| } |
| } |
| |
| |
| ParScanClosure::ParScanClosure(ParNewGeneration* g, |
| ParScanThreadState* par_scan_state) : |
| OopsInGenClosure(g), _par_scan_state(par_scan_state), _g(g) |
| { |
| assert(_g->level() == 0, "Optimized for youngest generation"); |
| _boundary = _g->reserved().end(); |
| } |
| |
| ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
| ParScanThreadState* par_scan_state) |
| : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) |
| { |
| } |
| |
| #ifdef WIN32 |
| #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ |
| #endif |
| |
| ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( |
| ParScanThreadState* par_scan_state_, |
| ParScanWithoutBarrierClosure* to_space_closure_, |
| ParScanWithBarrierClosure* old_gen_closure_, |
| ParRootScanWithoutBarrierClosure* to_space_root_closure_, |
| ParNewGeneration* par_gen_, |
| ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, |
| ObjToScanQueueSet* task_queues_, |
| ParallelTaskTerminator* terminator_) : |
| |
| _par_scan_state(par_scan_state_), |
| _to_space_closure(to_space_closure_), |
| _old_gen_closure(old_gen_closure_), |
| _to_space_root_closure(to_space_root_closure_), |
| _old_gen_root_closure(old_gen_root_closure_), |
| _par_gen(par_gen_), |
| _task_queues(task_queues_), |
| _terminator(terminator_) |
| {} |
| |
| void ParEvacuateFollowersClosure::do_void() { |
| ObjToScanQueue* work_q = par_scan_state()->work_queue(); |
| |
| while (true) { |
| |
| // Scan to-space and old-gen objs until we run out of both. |
| oop obj_to_scan; |
| par_scan_state()->trim_queues(0); |
| |
| // We have no local work, attempt to steal from other threads. |
| |
| // attempt to steal work from promoted. |
| par_scan_state()->note_steal_attempt(); |
| if (task_queues()->steal(par_scan_state()->thread_num(), |
| par_scan_state()->hash_seed(), |
| obj_to_scan)) { |
| par_scan_state()->note_steal(); |
| bool res = work_q->push(obj_to_scan); |
| assert(res, "Empty queue should have room for a push."); |
| |
| par_scan_state()->note_push(); |
| // if successful, goto Start. |
| continue; |
| |
| // try global overflow list. |
| } else if (par_gen()->take_from_overflow_list(par_scan_state())) { |
| continue; |
| } |
| |
| // Otherwise, offer termination. |
| par_scan_state()->start_term_time(); |
| if (terminator()->offer_termination()) break; |
| par_scan_state()->end_term_time(); |
| } |
| // Finish the last termination pause. |
| par_scan_state()->end_term_time(); |
| } |
| |
| ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, |
| HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : |
| AbstractGangTask("ParNewGeneration collection"), |
| _gen(gen), _next_gen(next_gen), |
| _young_old_boundary(young_old_boundary), |
| _state_set(state_set) |
| {} |
| |
| void ParNewGenTask::work(int i) { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| // Since this is being done in a separate thread, need new resource |
| // and handle marks. |
| ResourceMark rm; |
| HandleMark hm; |
| // We would need multiple old-gen queues otherwise. |
| guarantee(gch->n_gens() == 2, |
| "Par young collection currently only works with one older gen."); |
| |
| Generation* old_gen = gch->next_gen(_gen); |
| |
| ParScanThreadState& par_scan_state = _state_set->thread_sate(i); |
| par_scan_state.set_young_old_boundary(_young_old_boundary); |
| |
| par_scan_state.start_strong_roots(); |
| gch->gen_process_strong_roots(_gen->level(), |
| true, // Process younger gens, if any, |
| // as strong roots. |
| false,// not collecting perm generation. |
| SharedHeap::SO_AllClasses, |
| &par_scan_state.older_gen_closure(), |
| &par_scan_state.to_space_root_closure()); |
| par_scan_state.end_strong_roots(); |
| |
| // "evacuate followers". |
| par_scan_state.evacuate_followers_closure().do_void(); |
| } |
| |
| #ifdef _MSC_VER |
| #pragma warning( push ) |
| #pragma warning( disable:4355 ) // 'this' : used in base member initializer list |
| #endif |
| ParNewGeneration:: |
| ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) |
| : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), |
| _overflow_list(NULL), |
| _is_alive_closure(this), |
| _plab_stats(YoungPLABSize, PLABWeight) |
| { |
| _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
| guarantee(_task_queues != NULL, "task_queues allocation failure."); |
| |
| for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { |
| ObjToScanQueuePadded *q_padded = new ObjToScanQueuePadded(); |
| guarantee(q_padded != NULL, "work_queue Allocation failure."); |
| |
| _task_queues->register_queue(i1, &q_padded->work_queue); |
| } |
| |
| for (uint i2 = 0; i2 < ParallelGCThreads; i2++) |
| _task_queues->queue(i2)->initialize(); |
| |
| if (UsePerfData) { |
| EXCEPTION_MARK; |
| ResourceMark rm; |
| |
| const char* cname = |
| PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); |
| PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, |
| ParallelGCThreads, CHECK); |
| } |
| } |
| #ifdef _MSC_VER |
| #pragma warning( pop ) |
| #endif |
| |
| // ParNewGeneration:: |
| ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : |
| DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} |
| |
| void |
| // ParNewGeneration:: |
| ParKeepAliveClosure::do_oop(oop* p) { |
| // We never expect to see a null reference being processed |
| // as a weak reference. |
| assert (*p != NULL, "expected non-null ref"); |
| assert ((*p)->is_oop(), "expected an oop while scanning weak refs"); |
| |
| _par_cl->do_oop_nv(p); |
| |
| if (Universe::heap()->is_in_reserved(p)) { |
| _rs->write_ref_field_gc_par(p, *p); |
| } |
| } |
| |
| // ParNewGeneration:: |
| KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : |
| DefNewGeneration::KeepAliveClosure(cl) {} |
| |
| void |
| // ParNewGeneration:: |
| KeepAliveClosure::do_oop(oop* p) { |
| // We never expect to see a null reference being processed |
| // as a weak reference. |
| assert (*p != NULL, "expected non-null ref"); |
| assert ((*p)->is_oop(), "expected an oop while scanning weak refs"); |
| |
| _cl->do_oop_nv(p); |
| |
| if (Universe::heap()->is_in_reserved(p)) { |
| _rs->write_ref_field_gc_par(p, *p); |
| } |
| } |
| |
| void ScanClosureWithParBarrier::do_oop(oop* p) { |
| oop obj = *p; |
| // Should we copy the obj? |
| if (obj != NULL) { |
| if ((HeapWord*)obj < _boundary) { |
| assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); |
| if (obj->is_forwarded()) { |
| *p = obj->forwardee(); |
| } else { |
| *p = _g->DefNewGeneration::copy_to_survivor_space(obj, p); |
| } |
| } |
| if (_gc_barrier) { |
| // If p points to a younger generation, mark the card. |
| if ((HeapWord*)obj < _gen_boundary) { |
| _rs->write_ref_field_gc_par(p, obj); |
| } |
| } |
| } |
| } |
| |
| class ParNewRefProcTaskProxy: public AbstractGangTask { |
| typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| public: |
| ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, |
| Generation& next_gen, |
| HeapWord* young_old_boundary, |
| ParScanThreadStateSet& state_set); |
| |
| private: |
| virtual void work(int i); |
| |
| private: |
| ParNewGeneration& _gen; |
| ProcessTask& _task; |
| Generation& _next_gen; |
| HeapWord* _young_old_boundary; |
| ParScanThreadStateSet& _state_set; |
| }; |
| |
| ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( |
| ProcessTask& task, ParNewGeneration& gen, |
| Generation& next_gen, |
| HeapWord* young_old_boundary, |
| ParScanThreadStateSet& state_set) |
| : AbstractGangTask("ParNewGeneration parallel reference processing"), |
| _gen(gen), |
| _task(task), |
| _next_gen(next_gen), |
| _young_old_boundary(young_old_boundary), |
| _state_set(state_set) |
| { |
| } |
| |
| void ParNewRefProcTaskProxy::work(int i) |
| { |
| ResourceMark rm; |
| HandleMark hm; |
| ParScanThreadState& par_scan_state = _state_set.thread_sate(i); |
| par_scan_state.set_young_old_boundary(_young_old_boundary); |
| _task.work(i, par_scan_state.is_alive_closure(), |
| par_scan_state.keep_alive_closure(), |
| par_scan_state.evacuate_followers_closure()); |
| } |
| |
| class ParNewRefEnqueueTaskProxy: public AbstractGangTask { |
| typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; |
| EnqueueTask& _task; |
| |
| public: |
| ParNewRefEnqueueTaskProxy(EnqueueTask& task) |
| : AbstractGangTask("ParNewGeneration parallel reference enqueue"), |
| _task(task) |
| { } |
| |
| virtual void work(int i) |
| { |
| _task.work(i); |
| } |
| }; |
| |
| |
| void ParNewRefProcTaskExecutor::execute(ProcessTask& task) |
| { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| assert(gch->kind() == CollectedHeap::GenCollectedHeap, |
| "not a generational heap"); |
| WorkGang* workers = gch->workers(); |
| assert(workers != NULL, "Need parallel worker threads."); |
| ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), |
| _generation.reserved().end(), _state_set); |
| workers->run_task(&rp_task); |
| _state_set.reset(); |
| } |
| |
| void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) |
| { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| WorkGang* workers = gch->workers(); |
| assert(workers != NULL, "Need parallel worker threads."); |
| ParNewRefEnqueueTaskProxy enq_task(task); |
| workers->run_task(&enq_task); |
| } |
| |
| void ParNewRefProcTaskExecutor::set_single_threaded_mode() |
| { |
| _state_set.flush(); |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| gch->set_par_threads(0); // 0 ==> non-parallel. |
| gch->save_marks(); |
| } |
| |
| ScanClosureWithParBarrier:: |
| ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : |
| ScanClosure(g, gc_barrier) {} |
| |
| EvacuateFollowersClosureGeneral:: |
| EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, |
| OopsInGenClosure* cur, |
| OopsInGenClosure* older) : |
| _gch(gch), _level(level), |
| _scan_cur_or_nonheap(cur), _scan_older(older) |
| {} |
| |
| void EvacuateFollowersClosureGeneral::do_void() { |
| do { |
| // Beware: this call will lead to closure applications via virtual |
| // calls. |
| _gch->oop_since_save_marks_iterate(_level, |
| _scan_cur_or_nonheap, |
| _scan_older); |
| } while (!_gch->no_allocs_since_save_marks(_level)); |
| } |
| |
| |
| bool ParNewGeneration::_avoid_promotion_undo = false; |
| |
| void ParNewGeneration::adjust_desired_tenuring_threshold() { |
| // Set the desired survivor size to half the real survivor space |
| _tenuring_threshold = |
| age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); |
| } |
| |
| // A Generation that does parallel young-gen collection. |
| |
| void ParNewGeneration::collect(bool full, |
| bool clear_all_soft_refs, |
| size_t size, |
| bool is_tlab) { |
| assert(full || size > 0, "otherwise we don't want to collect"); |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| assert(gch->kind() == CollectedHeap::GenCollectedHeap, |
| "not a CMS generational heap"); |
| AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); |
| WorkGang* workers = gch->workers(); |
| _next_gen = gch->next_gen(this); |
| assert(_next_gen != NULL, |
| "This must be the youngest gen, and not the only gen"); |
| assert(gch->n_gens() == 2, |
| "Par collection currently only works with single older gen."); |
| // Do we have to avoid promotion_undo? |
| if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { |
| set_avoid_promotion_undo(true); |
| } |
| |
| // If the next generation is too full to accomodate worst-case promotion |
| // from this generation, pass on collection; let the next generation |
| // do it. |
| if (!collection_attempt_is_safe()) { |
| gch->set_incremental_collection_will_fail(); |
| return; |
| } |
| assert(to()->is_empty(), "Else not collection_attempt_is_safe"); |
| |
| init_assuming_no_promotion_failure(); |
| |
| if (UseAdaptiveSizePolicy) { |
| set_survivor_overflow(false); |
| size_policy->minor_collection_begin(); |
| } |
| |
| TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); |
| // Capture heap used before collection (for printing). |
| size_t gch_prev_used = gch->used(); |
| |
| SpecializationStats::clear(); |
| |
| age_table()->clear(); |
| to()->clear(); |
| |
| gch->save_marks(); |
| assert(workers != NULL, "Need parallel worker threads."); |
| ParallelTaskTerminator _term(workers->total_workers(), task_queues()); |
| ParScanThreadStateSet thread_state_set(workers->total_workers(), |
| *to(), *this, *_next_gen, *task_queues(), |
| desired_plab_sz(), _term); |
| |
| ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); |
| int n_workers = workers->total_workers(); |
| gch->set_par_threads(n_workers); |
| gch->change_strong_roots_parity(); |
| gch->rem_set()->prepare_for_younger_refs_iterate(true); |
| // It turns out that even when we're using 1 thread, doing the work in a |
| // separate thread causes wide variance in run times. We can't help this |
| // in the multi-threaded case, but we special-case n=1 here to get |
| // repeatable measurements of the 1-thread overhead of the parallel code. |
| if (n_workers > 1) { |
| workers->run_task(&tsk); |
| } else { |
| tsk.work(0); |
| } |
| thread_state_set.reset(); |
| |
| if (PAR_STATS_ENABLED && ParallelGCVerbose) { |
| gclog_or_tty->print("Thread totals:\n" |
| " Pushes: %7d Pops: %7d Steals %7d (sum = %7d).\n", |
| thread_state_set.pushes(), thread_state_set.pops(), |
| thread_state_set.steals(), |
| thread_state_set.pops()+thread_state_set.steals()); |
| } |
| assert(thread_state_set.pushes() == thread_state_set.pops() + thread_state_set.steals(), |
| "Or else the queues are leaky."); |
| |
| // For now, process discovered weak refs sequentially. |
| #ifdef COMPILER2 |
| ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy(); |
| #else |
| ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy(); |
| #endif // COMPILER2 |
| |
| // Process (weak) reference objects found during scavenge. |
| IsAliveClosure is_alive(this); |
| ScanWeakRefClosure scan_weak_ref(this); |
| KeepAliveClosure keep_alive(&scan_weak_ref); |
| ScanClosure scan_without_gc_barrier(this, false); |
| ScanClosureWithParBarrier scan_with_gc_barrier(this, true); |
| set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); |
| EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, |
| &scan_without_gc_barrier, &scan_with_gc_barrier); |
| if (ref_processor()->processing_is_mt()) { |
| ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
| ref_processor()->process_discovered_references( |
| soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, |
| &task_executor); |
| } else { |
| thread_state_set.flush(); |
| gch->set_par_threads(0); // 0 ==> non-parallel. |
| gch->save_marks(); |
| ref_processor()->process_discovered_references( |
| soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, |
| NULL); |
| } |
| if (!promotion_failed()) { |
| // Swap the survivor spaces. |
| eden()->clear(); |
| from()->clear(); |
| swap_spaces(); |
| |
| assert(to()->is_empty(), "to space should be empty now"); |
| } else { |
| assert(HandlePromotionFailure, |
| "Should only be here if promotion failure handling is on"); |
| if (_promo_failure_scan_stack != NULL) { |
| // Can be non-null because of reference processing. |
| // Free stack with its elements. |
| delete _promo_failure_scan_stack; |
| _promo_failure_scan_stack = NULL; |
| } |
| remove_forwarding_pointers(); |
| if (PrintGCDetails) { |
| gclog_or_tty->print(" (promotion failed)"); |
| } |
| // All the spaces are in play for mark-sweep. |
| swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. |
| from()->set_next_compaction_space(to()); |
| gch->set_incremental_collection_will_fail(); |
| } |
| // set new iteration safe limit for the survivor spaces |
| from()->set_concurrent_iteration_safe_limit(from()->top()); |
| to()->set_concurrent_iteration_safe_limit(to()->top()); |
| |
| adjust_desired_tenuring_threshold(); |
| if (ResizePLAB) { |
| plab_stats()->adjust_desired_plab_sz(); |
| } |
| |
| if (PrintGC && !PrintGCDetails) { |
| gch->print_heap_change(gch_prev_used); |
| } |
| |
| if (UseAdaptiveSizePolicy) { |
| size_policy->minor_collection_end(gch->gc_cause()); |
| size_policy->avg_survived()->sample(from()->used()); |
| } |
| |
| update_time_of_last_gc(os::javaTimeMillis()); |
| |
| SpecializationStats::print(); |
| |
| ref_processor()->set_enqueuing_is_done(true); |
| if (ref_processor()->processing_is_mt()) { |
| ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
| ref_processor()->enqueue_discovered_references(&task_executor); |
| } else { |
| ref_processor()->enqueue_discovered_references(NULL); |
| } |
| ref_processor()->verify_no_references_recorded(); |
| } |
| |
| static int sum; |
| void ParNewGeneration::waste_some_time() { |
| for (int i = 0; i < 100; i++) { |
| sum += i; |
| } |
| } |
| |
| static const oop ClaimedForwardPtr = oop(0x4); |
| |
| // Because of concurrency, there are times where an object for which |
| // "is_forwarded()" is true contains an "interim" forwarding pointer |
| // value. Such a value will soon be overwritten with a real value. |
| // This method requires "obj" to have a forwarding pointer, and waits, if |
| // necessary for a real one to be inserted, and returns it. |
| |
| oop ParNewGeneration::real_forwardee(oop obj) { |
| oop forward_ptr = obj->forwardee(); |
| if (forward_ptr != ClaimedForwardPtr) { |
| return forward_ptr; |
| } else { |
| return real_forwardee_slow(obj); |
| } |
| } |
| |
| oop ParNewGeneration::real_forwardee_slow(oop obj) { |
| // Spin-read if it is claimed but not yet written by another thread. |
| oop forward_ptr = obj->forwardee(); |
| while (forward_ptr == ClaimedForwardPtr) { |
| waste_some_time(); |
| assert(obj->is_forwarded(), "precondition"); |
| forward_ptr = obj->forwardee(); |
| } |
| return forward_ptr; |
| } |
| |
| #ifdef ASSERT |
| bool ParNewGeneration::is_legal_forward_ptr(oop p) { |
| return |
| (_avoid_promotion_undo && p == ClaimedForwardPtr) |
| || Universe::heap()->is_in_reserved(p); |
| } |
| #endif |
| |
| void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { |
| if ((m != markOopDesc::prototype()) && |
| (!UseBiasedLocking || (m != markOopDesc::biased_locking_prototype()))) { |
| MutexLocker ml(ParGCRareEvent_lock); |
| DefNewGeneration::preserve_mark_if_necessary(obj, m); |
| } |
| } |
| |
| // Multiple GC threads may try to promote an object. If the object |
| // is successfully promoted, a forwarding pointer will be installed in |
| // the object in the young generation. This method claims the right |
| // to install the forwarding pointer before it copies the object, |
| // thus avoiding the need to undo the copy as in |
| // copy_to_survivor_space_avoiding_with_undo. |
| |
| oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( |
| ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { |
| // In the sequential version, this assert also says that the object is |
| // not forwarded. That might not be the case here. It is the case that |
| // the caller observed it to be not forwarded at some time in the past. |
| assert(is_in_reserved(old), "shouldn't be scavenging this oop"); |
| |
| // The sequential code read "old->age()" below. That doesn't work here, |
| // since the age is in the mark word, and that might be overwritten with |
| // a forwarding pointer by a parallel thread. So we must save the mark |
| // word in a local and then analyze it. |
| oopDesc dummyOld; |
| dummyOld.set_mark(m); |
| assert(!dummyOld.is_forwarded(), |
| "should not be called with forwarding pointer mark word."); |
| |
| oop new_obj = NULL; |
| oop forward_ptr; |
| |
| // Try allocating obj in to-space (unless too old) |
| if (dummyOld.age() < tenuring_threshold()) { |
| new_obj = (oop)par_scan_state->alloc_in_to_space(sz); |
| if (new_obj == NULL) { |
| set_survivor_overflow(true); |
| } |
| } |
| |
| if (new_obj == NULL) { |
| // Either to-space is full or we decided to promote |
| // try allocating obj tenured |
| |
| // Attempt to install a null forwarding pointer (atomically), |
| // to claim the right to install the real forwarding pointer. |
| forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); |
| if (forward_ptr != NULL) { |
| // someone else beat us to it. |
| return real_forwardee(old); |
| } |
| |
| new_obj = _next_gen->par_promote(par_scan_state->thread_num(), |
| old, m, sz); |
| |
| if (new_obj == NULL) { |
| if (!HandlePromotionFailure) { |
| // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag |
| // is incorrectly set. In any case, its seriously wrong to be here! |
| vm_exit_out_of_memory(sz*wordSize, "promotion"); |
| } |
| // promotion failed, forward to self |
| _promotion_failed = true; |
| new_obj = old; |
| |
| preserve_mark_if_necessary(old, m); |
| } |
| |
| old->forward_to(new_obj); |
| forward_ptr = NULL; |
| } else { |
| // Is in to-space; do copying ourselves. |
| Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); |
| forward_ptr = old->forward_to_atomic(new_obj); |
| // Restore the mark word copied above. |
| new_obj->set_mark(m); |
| // Increment age if obj still in new generation |
| new_obj->incr_age(); |
| par_scan_state->age_table()->add(new_obj, sz); |
| } |
| assert(new_obj != NULL, "just checking"); |
| |
| if (forward_ptr == NULL) { |
| oop obj_to_push = new_obj; |
| if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { |
| // Length field used as index of next element to be scanned. |
| // Real length can be obtained from real_forwardee() |
| arrayOop(old)->set_length(0); |
| obj_to_push = old; |
| assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, |
| "push forwarded object"); |
| } |
| // Push it on one of the queues of to-be-scanned objects. |
| if (!par_scan_state->work_queue()->push(obj_to_push)) { |
| // Add stats for overflow pushes. |
| if (Verbose && PrintGCDetails) { |
| gclog_or_tty->print("queue overflow!\n"); |
| } |
| push_on_overflow_list(old); |
| par_scan_state->note_overflow_push(); |
| } |
| par_scan_state->note_push(); |
| |
| return new_obj; |
| } |
| |
| // Oops. Someone beat us to it. Undo the allocation. Where did we |
| // allocate it? |
| if (is_in_reserved(new_obj)) { |
| // Must be in to_space. |
| assert(to()->is_in_reserved(new_obj), "Checking"); |
| if (forward_ptr == ClaimedForwardPtr) { |
| // Wait to get the real forwarding pointer value. |
| forward_ptr = real_forwardee(old); |
| } |
| par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); |
| } |
| |
| return forward_ptr; |
| } |
| |
| |
| // Multiple GC threads may try to promote the same object. If two |
| // or more GC threads copy the object, only one wins the race to install |
| // the forwarding pointer. The other threads have to undo their copy. |
| |
| oop ParNewGeneration::copy_to_survivor_space_with_undo( |
| ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { |
| |
| // In the sequential version, this assert also says that the object is |
| // not forwarded. That might not be the case here. It is the case that |
| // the caller observed it to be not forwarded at some time in the past. |
| assert(is_in_reserved(old), "shouldn't be scavenging this oop"); |
| |
| // The sequential code read "old->age()" below. That doesn't work here, |
| // since the age is in the mark word, and that might be overwritten with |
| // a forwarding pointer by a parallel thread. So we must save the mark |
| // word here, install it in a local oopDesc, and then analyze it. |
| oopDesc dummyOld; |
| dummyOld.set_mark(m); |
| assert(!dummyOld.is_forwarded(), |
| "should not be called with forwarding pointer mark word."); |
| |
| bool failed_to_promote = false; |
| oop new_obj = NULL; |
| oop forward_ptr; |
| |
| // Try allocating obj in to-space (unless too old) |
| if (dummyOld.age() < tenuring_threshold()) { |
| new_obj = (oop)par_scan_state->alloc_in_to_space(sz); |
| if (new_obj == NULL) { |
| set_survivor_overflow(true); |
| } |
| } |
| |
| if (new_obj == NULL) { |
| // Either to-space is full or we decided to promote |
| // try allocating obj tenured |
| new_obj = _next_gen->par_promote(par_scan_state->thread_num(), |
| old, m, sz); |
| |
| if (new_obj == NULL) { |
| if (!HandlePromotionFailure) { |
| // A failed promotion likely means the MaxLiveObjectEvacuationRatio |
| // flag is incorrectly set. In any case, its seriously wrong to be |
| // here! |
| vm_exit_out_of_memory(sz*wordSize, "promotion"); |
| } |
| // promotion failed, forward to self |
| forward_ptr = old->forward_to_atomic(old); |
| new_obj = old; |
| |
| if (forward_ptr != NULL) { |
| return forward_ptr; // someone else succeeded |
| } |
| |
| _promotion_failed = true; |
| failed_to_promote = true; |
| |
| preserve_mark_if_necessary(old, m); |
| } |
| } else { |
| // Is in to-space; do copying ourselves. |
| Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); |
| // Restore the mark word copied above. |
| new_obj->set_mark(m); |
| // Increment age if new_obj still in new generation |
| new_obj->incr_age(); |
| par_scan_state->age_table()->add(new_obj, sz); |
| } |
| assert(new_obj != NULL, "just checking"); |
| |
| // Now attempt to install the forwarding pointer (atomically). |
| // We have to copy the mark word before overwriting with forwarding |
| // ptr, so we can restore it below in the copy. |
| if (!failed_to_promote) { |
| forward_ptr = old->forward_to_atomic(new_obj); |
| } |
| |
| if (forward_ptr == NULL) { |
| oop obj_to_push = new_obj; |
| if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { |
| // Length field used as index of next element to be scanned. |
| // Real length can be obtained from real_forwardee() |
| arrayOop(old)->set_length(0); |
| obj_to_push = old; |
| assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, |
| "push forwarded object"); |
| } |
| // Push it on one of the queues of to-be-scanned objects. |
| if (!par_scan_state->work_queue()->push(obj_to_push)) { |
| // Add stats for overflow pushes. |
| push_on_overflow_list(old); |
| par_scan_state->note_overflow_push(); |
| } |
| par_scan_state->note_push(); |
| |
| return new_obj; |
| } |
| |
| // Oops. Someone beat us to it. Undo the allocation. Where did we |
| // allocate it? |
| if (is_in_reserved(new_obj)) { |
| // Must be in to_space. |
| assert(to()->is_in_reserved(new_obj), "Checking"); |
| par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); |
| } else { |
| assert(!_avoid_promotion_undo, "Should not be here if avoiding."); |
| _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), |
| (HeapWord*)new_obj, sz); |
| } |
| |
| return forward_ptr; |
| } |
| |
| void ParNewGeneration::push_on_overflow_list(oop from_space_obj) { |
| oop cur_overflow_list = _overflow_list; |
| // if the object has been forwarded to itself, then we cannot |
| // use the klass pointer for the linked list. Instead we have |
| // to allocate an oopDesc in the C-Heap and use that for the linked list. |
| if (from_space_obj->forwardee() == from_space_obj) { |
| oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1); |
| listhead->forward_to(from_space_obj); |
| from_space_obj = listhead; |
| } |
| while (true) { |
| from_space_obj->set_klass_to_list_ptr(cur_overflow_list); |
| oop observed_overflow_list = |
| (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
| if (observed_overflow_list == cur_overflow_list) break; |
| // Otherwise... |
| cur_overflow_list = observed_overflow_list; |
| } |
| } |
| |
| bool |
| ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { |
| ObjToScanQueue* work_q = par_scan_state->work_queue(); |
| // How many to take? |
| int objsFromOverflow = MIN2(work_q->max_elems()/4, |
| (juint)ParGCDesiredObjsFromOverflowList); |
| |
| if (_overflow_list == NULL) return false; |
| |
| // Otherwise, there was something there; try claiming the list. |
| oop prefix = (oop)Atomic::xchg_ptr(NULL, &_overflow_list); |
| |
| if (prefix == NULL) { |
| return false; |
| } |
| // Trim off a prefix of at most objsFromOverflow items |
| int i = 1; |
| oop cur = prefix; |
| while (i < objsFromOverflow && cur->klass() != NULL) { |
| i++; cur = oop(cur->klass()); |
| } |
| |
| // Reattach remaining (suffix) to overflow list |
| if (cur->klass() != NULL) { |
| oop suffix = oop(cur->klass()); |
| cur->set_klass_to_list_ptr(NULL); |
| |
| // Find last item of suffix list |
| oop last = suffix; |
| while (last->klass() != NULL) { |
| last = oop(last->klass()); |
| } |
| // Atomically prepend suffix to current overflow list |
| oop cur_overflow_list = _overflow_list; |
| while (true) { |
| last->set_klass_to_list_ptr(cur_overflow_list); |
| oop observed_overflow_list = |
| (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); |
| if (observed_overflow_list == cur_overflow_list) break; |
| // Otherwise... |
| cur_overflow_list = observed_overflow_list; |
| } |
| } |
| |
| // Push objects on prefix list onto this thread's work queue |
| assert(cur != NULL, "program logic"); |
| cur = prefix; |
| int n = 0; |
| while (cur != NULL) { |
| oop obj_to_push = cur->forwardee(); |
| oop next = oop(cur->klass()); |
| cur->set_klass(obj_to_push->klass()); |
| if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { |
| obj_to_push = cur; |
| assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
| } |
| work_q->push(obj_to_push); |
| cur = next; |
| n++; |
| } |
| par_scan_state->note_overflow_refill(n); |
| return true; |
| } |
| |
| void ParNewGeneration::ref_processor_init() |
| { |
| if (_ref_processor == NULL) { |
| // Allocate and initialize a reference processor |
| _ref_processor = ReferenceProcessor::create_ref_processor( |
| _reserved, // span |
| refs_discovery_is_atomic(), // atomic_discovery |
| refs_discovery_is_mt(), // mt_discovery |
| NULL, // is_alive_non_header |
| ParallelGCThreads, |
| ParallelRefProcEnabled); |
| } |
| } |
| |
| const char* ParNewGeneration::name() const { |
| return "par new generation"; |
| } |
