Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @ 2388:006b3750a4d4
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author | jcoomes |
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date | Thu, 24 Mar 2011 23:06:13 -0700 |
parents | 92da084fefc9 |
children | 455328d90876 |
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/* * Copyright (c) 2001, 2011, 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 "code/icBuffer.hpp" #include "gc_implementation/g1/bufferingOopClosure.hpp" #include "gc_implementation/g1/concurrentG1Refine.hpp" #include "gc_implementation/g1/concurrentG1RefineThread.hpp" #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" #include "gc_implementation/g1/g1CollectorPolicy.hpp" #include "gc_implementation/g1/g1MarkSweep.hpp" #include "gc_implementation/g1/g1OopClosures.inline.hpp" #include "gc_implementation/g1/g1RemSet.inline.hpp" #include "gc_implementation/g1/heapRegionRemSet.hpp" #include "gc_implementation/g1/heapRegionSeq.inline.hpp" #include "gc_implementation/g1/vm_operations_g1.hpp" #include "gc_implementation/shared/isGCActiveMark.hpp" #include "memory/gcLocker.inline.hpp" #include "memory/genOopClosures.inline.hpp" #include "memory/generationSpec.hpp" #include "oops/oop.inline.hpp" #include "oops/oop.pcgc.inline.hpp" #include "runtime/aprofiler.hpp" #include "runtime/vmThread.hpp" size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; // turn it on so that the contents of the young list (scan-only / // to-be-collected) are printed at "strategic" points before / during // / after the collection --- this is useful for debugging #define YOUNG_LIST_VERBOSE 0 // CURRENT STATUS // This file is under construction. Search for "FIXME". // INVARIANTS/NOTES // // All allocation activity covered by the G1CollectedHeap interface is // serialized by acquiring the HeapLock. This happens in mem_allocate // and allocate_new_tlab, which are the "entry" points to the // allocation code from the rest of the JVM. (Note that this does not // apply to TLAB allocation, which is not part of this interface: it // is done by clients of this interface.) // Local to this file. class RefineCardTableEntryClosure: public CardTableEntryClosure { SuspendibleThreadSet* _sts; G1RemSet* _g1rs; ConcurrentG1Refine* _cg1r; bool _concurrent; public: RefineCardTableEntryClosure(SuspendibleThreadSet* sts, G1RemSet* g1rs, ConcurrentG1Refine* cg1r) : _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true) {} bool do_card_ptr(jbyte* card_ptr, int worker_i) { bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false); // This path is executed by the concurrent refine or mutator threads, // concurrently, and so we do not care if card_ptr contains references // that point into the collection set. assert(!oops_into_cset, "should be"); if (_concurrent && _sts->should_yield()) { // Caller will actually yield. return false; } // Otherwise, we finished successfully; return true. return true; } void set_concurrent(bool b) { _concurrent = b; } }; class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure { int _calls; G1CollectedHeap* _g1h; CardTableModRefBS* _ctbs; int _histo[256]; public: ClearLoggedCardTableEntryClosure() : _calls(0) { _g1h = G1CollectedHeap::heap(); _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); for (int i = 0; i < 256; i++) _histo[i] = 0; } bool do_card_ptr(jbyte* card_ptr, int worker_i) { if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { _calls++; unsigned char* ujb = (unsigned char*)card_ptr; int ind = (int)(*ujb); _histo[ind]++; *card_ptr = -1; } return true; } int calls() { return _calls; } void print_histo() { gclog_or_tty->print_cr("Card table value histogram:"); for (int i = 0; i < 256; i++) { if (_histo[i] != 0) { gclog_or_tty->print_cr(" %d: %d", i, _histo[i]); } } } }; class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure { int _calls; G1CollectedHeap* _g1h; CardTableModRefBS* _ctbs; public: RedirtyLoggedCardTableEntryClosure() : _calls(0) { _g1h = G1CollectedHeap::heap(); _ctbs = (CardTableModRefBS*)_g1h->barrier_set(); } bool do_card_ptr(jbyte* card_ptr, int worker_i) { if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) { _calls++; *card_ptr = 0; } return true; } int calls() { return _calls; } }; class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure { public: bool do_card_ptr(jbyte* card_ptr, int worker_i) { *card_ptr = CardTableModRefBS::dirty_card_val(); return true; } }; YoungList::YoungList(G1CollectedHeap* g1h) : _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { guarantee( check_list_empty(false), "just making sure..." ); } void YoungList::push_region(HeapRegion *hr) { assert(!hr->is_young(), "should not already be young"); assert(hr->get_next_young_region() == NULL, "cause it should!"); hr->set_next_young_region(_head); _head = hr; hr->set_young(); double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length); ++_length; } void YoungList::add_survivor_region(HeapRegion* hr) { assert(hr->is_survivor(), "should be flagged as survivor region"); assert(hr->get_next_young_region() == NULL, "cause it should!"); hr->set_next_young_region(_survivor_head); if (_survivor_head == NULL) { _survivor_tail = hr; } _survivor_head = hr; ++_survivor_length; } void YoungList::empty_list(HeapRegion* list) { while (list != NULL) { HeapRegion* next = list->get_next_young_region(); list->set_next_young_region(NULL); list->uninstall_surv_rate_group(); list->set_not_young(); list = next; } } void YoungList::empty_list() { assert(check_list_well_formed(), "young list should be well formed"); empty_list(_head); _head = NULL; _length = 0; empty_list(_survivor_head); _survivor_head = NULL; _survivor_tail = NULL; _survivor_length = 0; _last_sampled_rs_lengths = 0; assert(check_list_empty(false), "just making sure..."); } bool YoungList::check_list_well_formed() { bool ret = true; size_t length = 0; HeapRegion* curr = _head; HeapRegion* last = NULL; while (curr != NULL) { if (!curr->is_young()) { gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " "incorrectly tagged (y: %d, surv: %d)", curr->bottom(), curr->end(), curr->is_young(), curr->is_survivor()); ret = false; } ++length; last = curr; curr = curr->get_next_young_region(); } ret = ret && (length == _length); if (!ret) { gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); gclog_or_tty->print_cr("### list has %d entries, _length is %d", length, _length); } return ret; } bool YoungList::check_list_empty(bool check_sample) { bool ret = true; if (_length != 0) { gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d", _length); ret = false; } if (check_sample && _last_sampled_rs_lengths != 0) { gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); ret = false; } if (_head != NULL) { gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); ret = false; } if (!ret) { gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); } return ret; } void YoungList::rs_length_sampling_init() { _sampled_rs_lengths = 0; _curr = _head; } bool YoungList::rs_length_sampling_more() { return _curr != NULL; } void YoungList::rs_length_sampling_next() { assert( _curr != NULL, "invariant" ); size_t rs_length = _curr->rem_set()->occupied(); _sampled_rs_lengths += rs_length; // The current region may not yet have been added to the // incremental collection set (it gets added when it is // retired as the current allocation region). if (_curr->in_collection_set()) { // Update the collection set policy information for this region _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); } _curr = _curr->get_next_young_region(); if (_curr == NULL) { _last_sampled_rs_lengths = _sampled_rs_lengths; // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); } } void YoungList::reset_auxilary_lists() { guarantee( is_empty(), "young list should be empty" ); assert(check_list_well_formed(), "young list should be well formed"); // Add survivor regions to SurvRateGroup. _g1h->g1_policy()->note_start_adding_survivor_regions(); _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); for (HeapRegion* curr = _survivor_head; curr != NULL; curr = curr->get_next_young_region()) { _g1h->g1_policy()->set_region_survivors(curr); // The region is a non-empty survivor so let's add it to // the incremental collection set for the next evacuation // pause. _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); } _g1h->g1_policy()->note_stop_adding_survivor_regions(); _head = _survivor_head; _length = _survivor_length; if (_survivor_head != NULL) { assert(_survivor_tail != NULL, "cause it shouldn't be"); assert(_survivor_length > 0, "invariant"); _survivor_tail->set_next_young_region(NULL); } // Don't clear the survivor list handles until the start of // the next evacuation pause - we need it in order to re-tag // the survivor regions from this evacuation pause as 'young' // at the start of the next. _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); assert(check_list_well_formed(), "young list should be well formed"); } void YoungList::print() { HeapRegion* lists[] = {_head, _survivor_head}; const char* names[] = {"YOUNG", "SURVIVOR"}; for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) { gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); HeapRegion *curr = lists[list]; if (curr == NULL) gclog_or_tty->print_cr(" empty"); while (curr != NULL) { gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, " "age: %4d, y: %d, surv: %d", curr->bottom(), curr->end(), curr->top(), curr->prev_top_at_mark_start(), curr->next_top_at_mark_start(), curr->top_at_conc_mark_count(), curr->age_in_surv_rate_group_cond(), curr->is_young(), curr->is_survivor()); curr = curr->get_next_young_region(); } } gclog_or_tty->print_cr(""); } void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) { // Claim the right to put the region on the dirty cards region list // by installing a self pointer. HeapRegion* next = hr->get_next_dirty_cards_region(); if (next == NULL) { HeapRegion* res = (HeapRegion*) Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), NULL); if (res == NULL) { HeapRegion* head; do { // Put the region to the dirty cards region list. head = _dirty_cards_region_list; next = (HeapRegion*) Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); if (next == head) { assert(hr->get_next_dirty_cards_region() == hr, "hr->get_next_dirty_cards_region() != hr"); if (next == NULL) { // The last region in the list points to itself. hr->set_next_dirty_cards_region(hr); } else { hr->set_next_dirty_cards_region(next); } } } while (next != head); } } } HeapRegion* G1CollectedHeap::pop_dirty_cards_region() { HeapRegion* head; HeapRegion* hr; do { head = _dirty_cards_region_list; if (head == NULL) { return NULL; } HeapRegion* new_head = head->get_next_dirty_cards_region(); if (head == new_head) { // The last region. new_head = NULL; } hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, head); } while (hr != head); assert(hr != NULL, "invariant"); hr->set_next_dirty_cards_region(NULL); return hr; } void G1CollectedHeap::stop_conc_gc_threads() { _cg1r->stop(); _cmThread->stop(); } void G1CollectedHeap::check_ct_logs_at_safepoint() { DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set(); // Count the dirty cards at the start. CountNonCleanMemRegionClosure count1(this); ct_bs->mod_card_iterate(&count1); int orig_count = count1.n(); // First clear the logged cards. ClearLoggedCardTableEntryClosure clear; dcqs.set_closure(&clear); dcqs.apply_closure_to_all_completed_buffers(); dcqs.iterate_closure_all_threads(false); clear.print_histo(); // Now ensure that there's no dirty cards. CountNonCleanMemRegionClosure count2(this); ct_bs->mod_card_iterate(&count2); if (count2.n() != 0) { gclog_or_tty->print_cr("Card table has %d entries; %d originally", count2.n(), orig_count); } guarantee(count2.n() == 0, "Card table should be clean."); RedirtyLoggedCardTableEntryClosure redirty; JavaThread::dirty_card_queue_set().set_closure(&redirty); dcqs.apply_closure_to_all_completed_buffers(); dcqs.iterate_closure_all_threads(false); gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.", clear.calls(), orig_count); guarantee(redirty.calls() == clear.calls(), "Or else mechanism is broken."); CountNonCleanMemRegionClosure count3(this); ct_bs->mod_card_iterate(&count3); if (count3.n() != orig_count) { gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.", orig_count, count3.n()); guarantee(count3.n() >= orig_count, "Should have restored them all."); } JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); } // Private class members. G1CollectedHeap* G1CollectedHeap::_g1h; // Private methods. HeapRegion* G1CollectedHeap::new_region_try_secondary_free_list() { MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); while (!_secondary_free_list.is_empty() || free_regions_coming()) { if (!_secondary_free_list.is_empty()) { if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " "secondary_free_list has "SIZE_FORMAT" entries", _secondary_free_list.length()); } // It looks as if there are free regions available on the // secondary_free_list. Let's move them to the free_list and try // again to allocate from it. append_secondary_free_list(); assert(!_free_list.is_empty(), "if the secondary_free_list was not " "empty we should have moved at least one entry to the free_list"); HeapRegion* res = _free_list.remove_head(); if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " "allocated "HR_FORMAT" from secondary_free_list", HR_FORMAT_PARAMS(res)); } return res; } // Wait here until we get notifed either when (a) there are no // more free regions coming or (b) some regions have been moved on // the secondary_free_list. SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); } if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " "could not allocate from secondary_free_list"); } return NULL; } HeapRegion* G1CollectedHeap::new_region_work(size_t word_size, bool do_expand) { assert(!isHumongous(word_size) || word_size <= (size_t) HeapRegion::GrainWords, "the only time we use this to allocate a humongous region is " "when we are allocating a single humongous region"); HeapRegion* res; if (G1StressConcRegionFreeing) { if (!_secondary_free_list.is_empty()) { if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " "forced to look at the secondary_free_list"); } res = new_region_try_secondary_free_list(); if (res != NULL) { return res; } } } res = _free_list.remove_head_or_null(); if (res == NULL) { if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " "res == NULL, trying the secondary_free_list"); } res = new_region_try_secondary_free_list(); } if (res == NULL && do_expand) { if (expand(word_size * HeapWordSize)) { // The expansion succeeded and so we should have at least one // region on the free list. res = _free_list.remove_head(); } } if (res != NULL) { if (G1PrintHeapRegions) { gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT","PTR_FORMAT"], " "top "PTR_FORMAT, res->hrs_index(), res->bottom(), res->end(), res->top()); } } return res; } HeapRegion* G1CollectedHeap::new_gc_alloc_region(int purpose, size_t word_size) { HeapRegion* alloc_region = NULL; if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) { alloc_region = new_region_work(word_size, true /* do_expand */); if (purpose == GCAllocForSurvived && alloc_region != NULL) { alloc_region->set_survivor(); } ++_gc_alloc_region_counts[purpose]; } else { g1_policy()->note_alloc_region_limit_reached(purpose); } return alloc_region; } int G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions, size_t word_size) { assert(isHumongous(word_size), "word_size should be humongous"); assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); int first = -1; if (num_regions == 1) { // Only one region to allocate, no need to go through the slower // path. The caller will attempt the expasion if this fails, so // let's not try to expand here too. HeapRegion* hr = new_region_work(word_size, false /* do_expand */); if (hr != NULL) { first = hr->hrs_index(); } else { first = -1; } } else { // We can't allocate humongous regions while cleanupComplete() is // running, since some of the regions we find to be empty might not // yet be added to the free list and it is not straightforward to // know which list they are on so that we can remove them. Note // that we only need to do this if we need to allocate more than // one region to satisfy the current humongous allocation // request. If we are only allocating one region we use the common // region allocation code (see above). wait_while_free_regions_coming(); append_secondary_free_list_if_not_empty_with_lock(); if (free_regions() >= num_regions) { first = _hrs->find_contiguous(num_regions); if (first != -1) { for (int i = first; i < first + (int) num_regions; ++i) { HeapRegion* hr = _hrs->at(i); assert(hr->is_empty(), "sanity"); assert(is_on_master_free_list(hr), "sanity"); hr->set_pending_removal(true); } _free_list.remove_all_pending(num_regions); } } } return first; } HeapWord* G1CollectedHeap::humongous_obj_allocate_initialize_regions(int first, size_t num_regions, size_t word_size) { assert(first != -1, "pre-condition"); assert(isHumongous(word_size), "word_size should be humongous"); assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); // Index of last region in the series + 1. int last = first + (int) num_regions; // We need to initialize the region(s) we just discovered. This is // a bit tricky given that it can happen concurrently with // refinement threads refining cards on these regions and // potentially wanting to refine the BOT as they are scanning // those cards (this can happen shortly after a cleanup; see CR // 6991377). So we have to set up the region(s) carefully and in // a specific order. // The word size sum of all the regions we will allocate. size_t word_size_sum = num_regions * HeapRegion::GrainWords; assert(word_size <= word_size_sum, "sanity"); // This will be the "starts humongous" region. HeapRegion* first_hr = _hrs->at(first); // The header of the new object will be placed at the bottom of // the first region. HeapWord* new_obj = first_hr->bottom(); // This will be the new end of the first region in the series that // should also match the end of the last region in the seriers. HeapWord* new_end = new_obj + word_size_sum; // This will be the new top of the first region that will reflect // this allocation. HeapWord* new_top = new_obj + word_size; // First, we need to zero the header of the space that we will be // allocating. When we update top further down, some refinement // threads might try to scan the region. By zeroing the header we // ensure that any thread that will try to scan the region will // come across the zero klass word and bail out. // // NOTE: It would not have been correct to have used // CollectedHeap::fill_with_object() and make the space look like // an int array. The thread that is doing the allocation will // later update the object header to a potentially different array // type and, for a very short period of time, the klass and length // fields will be inconsistent. This could cause a refinement // thread to calculate the object size incorrectly. Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); // We will set up the first region as "starts humongous". This // will also update the BOT covering all the regions to reflect // that there is a single object that starts at the bottom of the // first region. first_hr->set_startsHumongous(new_top, new_end); // Then, if there are any, we will set up the "continues // humongous" regions. HeapRegion* hr = NULL; for (int i = first + 1; i < last; ++i) { hr = _hrs->at(i); hr->set_continuesHumongous(first_hr); } // If we have "continues humongous" regions (hr != NULL), then the // end of the last one should match new_end. assert(hr == NULL || hr->end() == new_end, "sanity"); // Up to this point no concurrent thread would have been able to // do any scanning on any region in this series. All the top // fields still point to bottom, so the intersection between // [bottom,top] and [card_start,card_end] will be empty. Before we // update the top fields, we'll do a storestore to make sure that // no thread sees the update to top before the zeroing of the // object header and the BOT initialization. OrderAccess::storestore(); // Now that the BOT and the object header have been initialized, // we can update top of the "starts humongous" region. assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), "new_top should be in this region"); first_hr->set_top(new_top); // Now, we will update the top fields of the "continues humongous" // regions. The reason we need to do this is that, otherwise, // these regions would look empty and this will confuse parts of // G1. For example, the code that looks for a consecutive number // of empty regions will consider them empty and try to // re-allocate them. We can extend is_empty() to also include // !continuesHumongous(), but it is easier to just update the top // fields here. The way we set top for all regions (i.e., top == // end for all regions but the last one, top == new_top for the // last one) is actually used when we will free up the humongous // region in free_humongous_region(). hr = NULL; for (int i = first + 1; i < last; ++i) { hr = _hrs->at(i); if ((i + 1) == last) { // last continues humongous region assert(hr->bottom() < new_top && new_top <= hr->end(), "new_top should fall on this region"); hr->set_top(new_top); } else { // not last one assert(new_top > hr->end(), "new_top should be above this region"); hr->set_top(hr->end()); } } // If we have continues humongous regions (hr != NULL), then the // end of the last one should match new_end and its top should // match new_top. assert(hr == NULL || (hr->end() == new_end && hr->top() == new_top), "sanity"); assert(first_hr->used() == word_size * HeapWordSize, "invariant"); _summary_bytes_used += first_hr->used(); _humongous_set.add(first_hr); return new_obj; } // If could fit into free regions w/o expansion, try. // Otherwise, if can expand, do so. // Otherwise, if using ex regions might help, try with ex given back. HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); verify_region_sets_optional(); size_t num_regions = round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; size_t x_size = expansion_regions(); size_t fs = _hrs->free_suffix(); int first = humongous_obj_allocate_find_first(num_regions, word_size); if (first == -1) { // The only thing we can do now is attempt expansion. if (fs + x_size >= num_regions) { // If the number of regions we're trying to allocate for this // object is at most the number of regions in the free suffix, // then the call to humongous_obj_allocate_find_first() above // should have succeeded and we wouldn't be here. // // We should only be trying to expand when the free suffix is // not sufficient for the object _and_ we have some expansion // room available. assert(num_regions > fs, "earlier allocation should have succeeded"); if (expand((num_regions - fs) * HeapRegion::GrainBytes)) { first = humongous_obj_allocate_find_first(num_regions, word_size); // If the expansion was successful then the allocation // should have been successful. assert(first != -1, "this should have worked"); } } } HeapWord* result = NULL; if (first != -1) { result = humongous_obj_allocate_initialize_regions(first, num_regions, word_size); assert(result != NULL, "it should always return a valid result"); } verify_region_sets_optional(); return result; } void G1CollectedHeap::retire_cur_alloc_region(HeapRegion* cur_alloc_region) { // Other threads might still be trying to allocate using CASes out // of the region we are retiring, as they can do so without holding // the Heap_lock. So we first have to make sure that noone else can // allocate in it by doing a maximal allocation. Even if our CAS // attempt fails a few times, we'll succeed sooner or later given // that a failed CAS attempt mean that the region is getting closed // to being full (someone else succeeded in allocating into it). size_t free_word_size = cur_alloc_region->free() / HeapWordSize; // This is the minimum free chunk we can turn into a dummy // object. If the free space falls below this, then noone can // allocate in this region anyway (all allocation requests will be // of a size larger than this) so we won't have to perform the dummy // allocation. size_t min_word_size_to_fill = CollectedHeap::min_fill_size(); while (free_word_size >= min_word_size_to_fill) { HeapWord* dummy = cur_alloc_region->par_allocate_no_bot_updates(free_word_size); if (dummy != NULL) { // If the allocation was successful we should fill in the space. CollectedHeap::fill_with_object(dummy, free_word_size); break; } free_word_size = cur_alloc_region->free() / HeapWordSize; // It's also possible that someone else beats us to the // allocation and they fill up the region. In that case, we can // just get out of the loop } assert(cur_alloc_region->free() / HeapWordSize < min_word_size_to_fill, "sanity"); retire_cur_alloc_region_common(cur_alloc_region); assert(_cur_alloc_region == NULL, "post-condition"); } // See the comment in the .hpp file about the locking protocol and // assumptions of this method (and other related ones). HeapWord* G1CollectedHeap::replace_cur_alloc_region_and_allocate(size_t word_size, bool at_safepoint, bool do_dirtying, bool can_expand) { assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); assert(_cur_alloc_region == NULL, "replace_cur_alloc_region_and_allocate() should only be called " "after retiring the previous current alloc region"); assert(SafepointSynchronize::is_at_safepoint() == at_safepoint, "at_safepoint and is_at_safepoint() should be a tautology"); assert(!can_expand || g1_policy()->can_expand_young_list(), "we should not call this method with can_expand == true if " "we are not allowed to expand the young gen"); if (can_expand || !g1_policy()->is_young_list_full()) { HeapRegion* new_cur_alloc_region = new_alloc_region(word_size); if (new_cur_alloc_region != NULL) { assert(new_cur_alloc_region->is_empty(), "the newly-allocated region should be empty, " "as right now we only allocate new regions out of the free list"); g1_policy()->update_region_num(true /* next_is_young */); set_region_short_lived_locked(new_cur_alloc_region); assert(!new_cur_alloc_region->isHumongous(), "Catch a regression of this bug."); // We need to ensure that the stores to _cur_alloc_region and, // subsequently, to top do not float above the setting of the // young type. OrderAccess::storestore(); // Now, perform the allocation out of the region we just // allocated. Note that noone else can access that region at // this point (as _cur_alloc_region has not been updated yet), // so we can just go ahead and do the allocation without any // atomics (and we expect this allocation attempt to // suceeded). Given that other threads can attempt an allocation // with a CAS and without needing the Heap_lock, if we assigned // the new region to _cur_alloc_region before first allocating // into it other threads might have filled up the new region // before we got a chance to do the allocation ourselves. In // that case, we would have needed to retire the region, grab a // new one, and go through all this again. Allocating out of the // new region before assigning it to _cur_alloc_region avoids // all this. HeapWord* result = new_cur_alloc_region->allocate_no_bot_updates(word_size); assert(result != NULL, "we just allocate out of an empty region " "so allocation should have been successful"); assert(is_in(result), "result should be in the heap"); // Now make sure that the store to _cur_alloc_region does not // float above the store to top. OrderAccess::storestore(); _cur_alloc_region = new_cur_alloc_region; if (!at_safepoint) { Heap_lock->unlock(); } // do the dirtying, if necessary, after we release the Heap_lock if (do_dirtying) { dirty_young_block(result, word_size); } return result; } } assert(_cur_alloc_region == NULL, "we failed to allocate a new current " "alloc region, it should still be NULL"); assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); return NULL; } // See the comment in the .hpp file about the locking protocol and // assumptions of this method (and other related ones). HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { assert_heap_locked_and_not_at_safepoint(); assert(!isHumongous(word_size), "attempt_allocation_slow() should not be " "used for humongous allocations"); // We should only reach here when we were unable to allocate // otherwise. So, we should have not active current alloc region. assert(_cur_alloc_region == NULL, "current alloc region should be NULL"); // We will loop while succeeded is false, which means that we tried // to do a collection, but the VM op did not succeed. So, when we // exit the loop, either one of the allocation attempts was // successful, or we succeeded in doing the VM op but which was // unable to allocate after the collection. for (int try_count = 1; /* we'll return or break */; try_count += 1) { bool succeeded = true; // Every time we go round the loop we should be holding the Heap_lock. assert_heap_locked(); if (GC_locker::is_active_and_needs_gc()) { // We are locked out of GC because of the GC locker. We can // allocate a new region only if we can expand the young gen. if (g1_policy()->can_expand_young_list()) { // Yes, we are allowed to expand the young gen. Let's try to // allocate a new current alloc region. HeapWord* result = replace_cur_alloc_region_and_allocate(word_size, false, /* at_safepoint */ true, /* do_dirtying */ true /* can_expand */); if (result != NULL) { assert_heap_not_locked(); return result; } } // We could not expand the young gen further (or we could but we // failed to allocate a new region). We'll stall until the GC // locker forces a GC. // If this thread is not in a jni critical section, we stall // the requestor until the critical section has cleared and // GC allowed. When the critical section clears, a GC is // initiated by the last thread exiting the critical section; so // we retry the allocation sequence from the beginning of the loop, // rather than causing more, now probably unnecessary, GC attempts. JavaThread* jthr = JavaThread::current(); assert(jthr != NULL, "sanity"); if (jthr->in_critical()) { if (CheckJNICalls) { fatal("Possible deadlock due to allocating while" " in jni critical section"); } // We are returning NULL so the protocol is that we're still // holding the Heap_lock. assert_heap_locked(); return NULL; } Heap_lock->unlock(); GC_locker::stall_until_clear(); // No need to relock the Heap_lock. We'll fall off to the code // below the else-statement which assumes that we are not // holding the Heap_lock. } else { // We are not locked out. So, let's try to do a GC. The VM op // will retry the allocation before it completes. // Read the GC count while holding the Heap_lock unsigned int gc_count_before = SharedHeap::heap()->total_collections(); Heap_lock->unlock(); HeapWord* result = do_collection_pause(word_size, gc_count_before, &succeeded); assert_heap_not_locked(); if (result != NULL) { assert(succeeded, "the VM op should have succeeded"); // Allocations that take place on VM operations do not do any // card dirtying and we have to do it here. dirty_young_block(result, word_size); return result; } } // Both paths that get us here from above unlock the Heap_lock. assert_heap_not_locked(); // We can reach here when we were unsuccessful in doing a GC, // because another thread beat us to it, or because we were locked // out of GC due to the GC locker. In either case a new alloc // region might be available so we will retry the allocation. HeapWord* result = attempt_allocation(word_size); if (result != NULL) { assert_heap_not_locked(); return result; } // So far our attempts to allocate failed. The only time we'll go // around the loop and try again is if we tried to do a GC and the // VM op that we tried to schedule was not successful because // another thread beat us to it. If that happened it's possible // that by the time we grabbed the Heap_lock again and tried to // allocate other threads filled up the young generation, which // means that the allocation attempt after the GC also failed. So, // it's worth trying to schedule another GC pause. if (succeeded) { break; } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { warning("G1CollectedHeap::attempt_allocation_slow() " "retries %d times", try_count); } } assert_heap_locked(); return NULL; } // See the comment in the .hpp file about the locking protocol and // assumptions of this method (and other related ones). HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, bool at_safepoint) { // This is the method that will allocate a humongous object. All // allocation paths that attempt to allocate a humongous object // should eventually reach here. Currently, the only paths are from // mem_allocate() and attempt_allocation_at_safepoint(). assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); assert(isHumongous(word_size), "attempt_allocation_humongous() " "should only be used for humongous allocations"); assert(SafepointSynchronize::is_at_safepoint() == at_safepoint, "at_safepoint and is_at_safepoint() should be a tautology"); HeapWord* result = NULL; // We will loop while succeeded is false, which means that we tried // to do a collection, but the VM op did not succeed. So, when we // exit the loop, either one of the allocation attempts was // successful, or we succeeded in doing the VM op but which was // unable to allocate after the collection. for (int try_count = 1; /* we'll return or break */; try_count += 1) { bool succeeded = true; // Given that humongous objects are not allocated in young // regions, we'll first try to do the allocation without doing a // collection hoping that there's enough space in the heap. result = humongous_obj_allocate(word_size); assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(), "catch a regression of this bug."); if (result != NULL) { if (!at_safepoint) { // If we're not at a safepoint, unlock the Heap_lock. Heap_lock->unlock(); } return result; } // If we failed to allocate the humongous object, we should try to // do a collection pause (if we're allowed) in case it reclaims // enough space for the allocation to succeed after the pause. if (!at_safepoint) { // Read the GC count while holding the Heap_lock unsigned int gc_count_before = SharedHeap::heap()->total_collections(); // If we're allowed to do a collection we're not at a // safepoint, so it is safe to unlock the Heap_lock. Heap_lock->unlock(); result = do_collection_pause(word_size, gc_count_before, &succeeded); assert_heap_not_locked(); if (result != NULL) { assert(succeeded, "the VM op should have succeeded"); return result; } // If we get here, the VM operation either did not succeed // (i.e., another thread beat us to it) or it succeeded but // failed to allocate the object. // If we're allowed to do a collection we're not at a // safepoint, so it is safe to lock the Heap_lock. Heap_lock->lock(); } assert(result == NULL, "otherwise we should have exited the loop earlier"); // So far our attempts to allocate failed. The only time we'll go // around the loop and try again is if we tried to do a GC and the // VM op that we tried to schedule was not successful because // another thread beat us to it. That way it's possible that some // space was freed up by the thread that successfully scheduled a // GC. So it's worth trying to allocate again. if (succeeded) { break; } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { warning("G1CollectedHeap::attempt_allocation_humongous " "retries %d times", try_count); } } assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); return NULL; } HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, bool expect_null_cur_alloc_region) { assert_at_safepoint(true /* should_be_vm_thread */); assert(_cur_alloc_region == NULL || !expect_null_cur_alloc_region, err_msg("the current alloc region was unexpectedly found " "to be non-NULL, cur alloc region: "PTR_FORMAT" " "expect_null_cur_alloc_region: %d word_size: "SIZE_FORMAT, _cur_alloc_region, expect_null_cur_alloc_region, word_size)); if (!isHumongous(word_size)) { if (!expect_null_cur_alloc_region) { HeapRegion* cur_alloc_region = _cur_alloc_region; if (cur_alloc_region != NULL) { // We are at a safepoint so no reason to use the MT-safe version. HeapWord* result = cur_alloc_region->allocate_no_bot_updates(word_size); if (result != NULL) { assert(is_in(result), "result should be in the heap"); // We will not do any dirtying here. This is guaranteed to be // called during a safepoint and the thread that scheduled the // pause will do the dirtying if we return a non-NULL result. return result; } retire_cur_alloc_region_common(cur_alloc_region); } } assert(_cur_alloc_region == NULL, "at this point we should have no cur alloc region"); return replace_cur_alloc_region_and_allocate(word_size, true, /* at_safepoint */ false /* do_dirtying */, false /* can_expand */); } else { return attempt_allocation_humongous(word_size, true /* at_safepoint */); } ShouldNotReachHere(); } HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { assert_heap_not_locked_and_not_at_safepoint(); assert(!isHumongous(word_size), "we do not allow TLABs of humongous size"); // First attempt: Try allocating out of the current alloc region // using a CAS. If that fails, take the Heap_lock and retry the // allocation, potentially replacing the current alloc region. HeapWord* result = attempt_allocation(word_size); if (result != NULL) { assert_heap_not_locked(); return result; } // Second attempt: Go to the slower path where we might try to // schedule a collection. result = attempt_allocation_slow(word_size); if (result != NULL) { assert_heap_not_locked(); return result; } assert_heap_locked(); // Need to unlock the Heap_lock before returning. Heap_lock->unlock(); return NULL; } HeapWord* G1CollectedHeap::mem_allocate(size_t word_size, bool is_noref, bool is_tlab, bool* gc_overhead_limit_was_exceeded) { assert_heap_not_locked_and_not_at_safepoint(); assert(!is_tlab, "mem_allocate() this should not be called directly " "to allocate TLABs"); // Loop until the allocation is satisified, // or unsatisfied after GC. for (int try_count = 1; /* we'll return */; try_count += 1) { unsigned int gc_count_before; { if (!isHumongous(word_size)) { // First attempt: Try allocating out of the current alloc region // using a CAS. If that fails, take the Heap_lock and retry the // allocation, potentially replacing the current alloc region. HeapWord* result = attempt_allocation(word_size); if (result != NULL) { assert_heap_not_locked(); return result; } assert_heap_locked(); // Second attempt: Go to the slower path where we might try to // schedule a collection. result = attempt_allocation_slow(word_size); if (result != NULL) { assert_heap_not_locked(); return result; } } else { // attempt_allocation_humongous() requires the Heap_lock to be held. Heap_lock->lock(); HeapWord* result = attempt_allocation_humongous(word_size, false /* at_safepoint */); if (result != NULL) { assert_heap_not_locked(); return result; } } assert_heap_locked(); // Read the gc count while the heap lock is held. gc_count_before = SharedHeap::heap()->total_collections(); // Release the Heap_lock before attempting the collection. Heap_lock->unlock(); } // Create the garbage collection operation... VM_G1CollectForAllocation op(gc_count_before, word_size); // ...and get the VM thread to execute it. VMThread::execute(&op); assert_heap_not_locked(); if (op.prologue_succeeded() && op.pause_succeeded()) { // If the operation was successful we'll return the result even // if it is NULL. If the allocation attempt failed immediately // after a Full GC, it's unlikely we'll be able to allocate now. HeapWord* result = op.result(); if (result != NULL && !isHumongous(word_size)) { // Allocations that take place on VM operations do not do any // card dirtying and we have to do it here. We only have to do // this for non-humongous allocations, though. dirty_young_block(result, word_size); } return result; } else { assert(op.result() == NULL, "the result should be NULL if the VM op did not succeed"); } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { warning("G1CollectedHeap::mem_allocate retries %d times", try_count); } } ShouldNotReachHere(); } void G1CollectedHeap::abandon_cur_alloc_region() { assert_at_safepoint(true /* should_be_vm_thread */); HeapRegion* cur_alloc_region = _cur_alloc_region; if (cur_alloc_region != NULL) { assert(!cur_alloc_region->is_empty(), "the current alloc region can never be empty"); assert(cur_alloc_region->is_young(), "the current alloc region should be young"); retire_cur_alloc_region_common(cur_alloc_region); } assert(_cur_alloc_region == NULL, "post-condition"); } void G1CollectedHeap::abandon_gc_alloc_regions() { // first, make sure that the GC alloc region list is empty (it should!) assert(_gc_alloc_region_list == NULL, "invariant"); release_gc_alloc_regions(true /* totally */); } class PostMCRemSetClearClosure: public HeapRegionClosure { ModRefBarrierSet* _mr_bs; public: PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {} bool doHeapRegion(HeapRegion* r) { r->reset_gc_time_stamp(); if (r->continuesHumongous()) return false; HeapRegionRemSet* hrrs = r->rem_set(); if (hrrs != NULL) hrrs->clear(); // You might think here that we could clear just the cards // corresponding to the used region. But no: if we leave a dirty card // in a region we might allocate into, then it would prevent that card // from being enqueued, and cause it to be missed. // Re: the performance cost: we shouldn't be doing full GC anyway! _mr_bs->clear(MemRegion(r->bottom(), r->end())); return false; } }; class PostMCRemSetInvalidateClosure: public HeapRegionClosure { ModRefBarrierSet* _mr_bs; public: PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {} bool doHeapRegion(HeapRegion* r) { if (r->continuesHumongous()) return false; if (r->used_region().word_size() != 0) { _mr_bs->invalidate(r->used_region(), true /*whole heap*/); } return false; } }; class RebuildRSOutOfRegionClosure: public HeapRegionClosure { G1CollectedHeap* _g1h; UpdateRSOopClosure _cl; int _worker_i; public: RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) : _cl(g1->g1_rem_set(), worker_i), _worker_i(worker_i), _g1h(g1) { } bool doHeapRegion(HeapRegion* r) { if (!r->continuesHumongous()) { _cl.set_from(r); r->oop_iterate(&_cl); } return false; } }; class ParRebuildRSTask: public AbstractGangTask { G1CollectedHeap* _g1; public: ParRebuildRSTask(G1CollectedHeap* g1) : AbstractGangTask("ParRebuildRSTask"), _g1(g1) { } void work(int i) { RebuildRSOutOfRegionClosure rebuild_rs(_g1, i); _g1->heap_region_par_iterate_chunked(&rebuild_rs, i, HeapRegion::RebuildRSClaimValue); } }; bool G1CollectedHeap::do_collection(bool explicit_gc, bool clear_all_soft_refs, size_t word_size) { assert_at_safepoint(true /* should_be_vm_thread */); if (GC_locker::check_active_before_gc()) { return false; } SvcGCMarker sgcm(SvcGCMarker::FULL); ResourceMark rm; if (PrintHeapAtGC) { Universe::print_heap_before_gc(); } verify_region_sets_optional(); const bool do_clear_all_soft_refs = clear_all_soft_refs || collector_policy()->should_clear_all_soft_refs(); ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); { IsGCActiveMark x; // Timing bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc); assert(!system_gc || explicit_gc, "invariant"); gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty); TraceMemoryManagerStats tms(true /* fullGC */); double start = os::elapsedTime(); g1_policy()->record_full_collection_start(); wait_while_free_regions_coming(); append_secondary_free_list_if_not_empty_with_lock(); gc_prologue(true); increment_total_collections(true /* full gc */); size_t g1h_prev_used = used(); assert(used() == recalculate_used(), "Should be equal"); if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification prepare_for_verify(); gclog_or_tty->print(" VerifyBeforeGC:"); Universe::verify(true); } COMPILER2_PRESENT(DerivedPointerTable::clear()); // We want to discover references, but not process them yet. // This mode is disabled in // instanceRefKlass::process_discovered_references if the // generation does some collection work, or // instanceRefKlass::enqueue_discovered_references if the // generation returns without doing any work. ref_processor()->disable_discovery(); ref_processor()->abandon_partial_discovery(); ref_processor()->verify_no_references_recorded(); // Abandon current iterations of concurrent marking and concurrent // refinement, if any are in progress. concurrent_mark()->abort(); // Make sure we'll choose a new allocation region afterwards. abandon_cur_alloc_region(); abandon_gc_alloc_regions(); assert(_cur_alloc_region == NULL, "Invariant."); g1_rem_set()->cleanupHRRS(); tear_down_region_lists(); // We may have added regions to the current incremental collection // set between the last GC or pause and now. We need to clear the // incremental collection set and then start rebuilding it afresh // after this full GC. abandon_collection_set(g1_policy()->inc_cset_head()); g1_policy()->clear_incremental_cset(); g1_policy()->stop_incremental_cset_building(); if (g1_policy()->in_young_gc_mode()) { empty_young_list(); g1_policy()->set_full_young_gcs(true); } // See the comment in G1CollectedHeap::ref_processing_init() about // how reference processing currently works in G1. // Temporarily make reference _discovery_ single threaded (non-MT). ReferenceProcessorMTDiscoveryMutator rp_disc_ser(ref_processor(), false); // Temporarily make refs discovery atomic ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true); // Temporarily clear _is_alive_non_header ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL); ref_processor()->enable_discovery(); ref_processor()->setup_policy(do_clear_all_soft_refs); // Do collection work { HandleMark hm; // Discard invalid handles created during gc G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs); } assert(free_regions() == 0, "we should not have added any free regions"); rebuild_region_lists(); _summary_bytes_used = recalculate_used(); ref_processor()->enqueue_discovered_references(); COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); MemoryService::track_memory_usage(); if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification gclog_or_tty->print(" VerifyAfterGC:"); prepare_for_verify(); Universe::verify(false); } NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); reset_gc_time_stamp(); // Since everything potentially moved, we will clear all remembered // sets, and clear all cards. Later we will rebuild remebered // sets. We will also reset the GC time stamps of the regions. PostMCRemSetClearClosure rs_clear(mr_bs()); heap_region_iterate(&rs_clear); // Resize the heap if necessary. resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); if (_cg1r->use_cache()) { _cg1r->clear_and_record_card_counts(); _cg1r->clear_hot_cache(); } // Rebuild remembered sets of all regions. if (G1CollectedHeap::use_parallel_gc_threads()) { ParRebuildRSTask rebuild_rs_task(this); assert(check_heap_region_claim_values( HeapRegion::InitialClaimValue), "sanity check"); set_par_threads(workers()->total_workers()); workers()->run_task(&rebuild_rs_task); set_par_threads(0); assert(check_heap_region_claim_values( HeapRegion::RebuildRSClaimValue), "sanity check"); reset_heap_region_claim_values(); } else { RebuildRSOutOfRegionClosure rebuild_rs(this); heap_region_iterate(&rebuild_rs); } if (PrintGC) { print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity()); } if (true) { // FIXME // Ask the permanent generation to adjust size for full collections perm()->compute_new_size(); } // Start a new incremental collection set for the next pause assert(g1_policy()->collection_set() == NULL, "must be"); g1_policy()->start_incremental_cset_building(); // Clear the _cset_fast_test bitmap in anticipation of adding // regions to the incremental collection set for the next // evacuation pause. clear_cset_fast_test(); double end = os::elapsedTime(); g1_policy()->record_full_collection_end(); #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif gc_epilogue(true); // Discard all rset updates JavaThread::dirty_card_queue_set().abandon_logs(); assert(!G1DeferredRSUpdate || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); } if (g1_policy()->in_young_gc_mode()) { _young_list->reset_sampled_info(); // At this point there should be no regions in the // entire heap tagged as young. assert( check_young_list_empty(true /* check_heap */), "young list should be empty at this point"); } // Update the number of full collections that have been completed. increment_full_collections_completed(false /* concurrent */); verify_region_sets_optional(); if (PrintHeapAtGC) { Universe::print_heap_after_gc(); } return true; } void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { // do_collection() will return whether it succeeded in performing // the GC. Currently, there is no facility on the // do_full_collection() API to notify the caller than the collection // did not succeed (e.g., because it was locked out by the GC // locker). So, right now, we'll ignore the return value. bool dummy = do_collection(true, /* explicit_gc */ clear_all_soft_refs, 0 /* word_size */); } // This code is mostly copied from TenuredGeneration. void G1CollectedHeap:: resize_if_necessary_after_full_collection(size_t word_size) { assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check"); // Include the current allocation, if any, and bytes that will be // pre-allocated to support collections, as "used". const size_t used_after_gc = used(); const size_t capacity_after_gc = capacity(); const size_t free_after_gc = capacity_after_gc - used_after_gc; // This is enforced in arguments.cpp. assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "otherwise the code below doesn't make sense"); // We don't have floating point command-line arguments const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; const double maximum_used_percentage = 1.0 - minimum_free_percentage; const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; const double minimum_used_percentage = 1.0 - maximum_free_percentage; const size_t min_heap_size = collector_policy()->min_heap_byte_size(); const size_t max_heap_size = collector_policy()->max_heap_byte_size(); // We have to be careful here as these two calculations can overflow // 32-bit size_t's. double used_after_gc_d = (double) used_after_gc; double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; // Let's make sure that they are both under the max heap size, which // by default will make them fit into a size_t. double desired_capacity_upper_bound = (double) max_heap_size; minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, desired_capacity_upper_bound); maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, desired_capacity_upper_bound); // We can now safely turn them into size_t's. size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; // This assert only makes sense here, before we adjust them // with respect to the min and max heap size. assert(minimum_desired_capacity <= maximum_desired_capacity, err_msg("minimum_desired_capacity = "SIZE_FORMAT", " "maximum_desired_capacity = "SIZE_FORMAT, minimum_desired_capacity, maximum_desired_capacity)); // Should not be greater than the heap max size. No need to adjust // it with respect to the heap min size as it's a lower bound (i.e., // we'll try to make the capacity larger than it, not smaller). minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); // Should not be less than the heap min size. No need to adjust it // with respect to the heap max size as it's an upper bound (i.e., // we'll try to make the capacity smaller than it, not greater). maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); if (PrintGC && Verbose) { const double free_percentage = (double) free_after_gc / (double) capacity_after_gc; gclog_or_tty->print_cr("Computing new size after full GC "); gclog_or_tty->print_cr(" " " minimum_free_percentage: %6.2f", minimum_free_percentage); gclog_or_tty->print_cr(" " " maximum_free_percentage: %6.2f", maximum_free_percentage); gclog_or_tty->print_cr(" " " capacity: %6.1fK" " minimum_desired_capacity: %6.1fK" " maximum_desired_capacity: %6.1fK", (double) capacity_after_gc / (double) K, (double) minimum_desired_capacity / (double) K, (double) maximum_desired_capacity / (double) K); gclog_or_tty->print_cr(" " " free_after_gc: %6.1fK" " used_after_gc: %6.1fK", (double) free_after_gc / (double) K, (double) used_after_gc / (double) K); gclog_or_tty->print_cr(" " " free_percentage: %6.2f", free_percentage); } if (capacity_after_gc < minimum_desired_capacity) { // Don't expand unless it's significant size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; if (expand(expand_bytes)) { if (PrintGC && Verbose) { gclog_or_tty->print_cr(" " " expanding:" " max_heap_size: %6.1fK" " minimum_desired_capacity: %6.1fK" " expand_bytes: %6.1fK", (double) max_heap_size / (double) K, (double) minimum_desired_capacity / (double) K, (double) expand_bytes / (double) K); } } // No expansion, now see if we want to shrink } else if (capacity_after_gc > maximum_desired_capacity) { // Capacity too large, compute shrinking size size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; shrink(shrink_bytes); if (PrintGC && Verbose) { gclog_or_tty->print_cr(" " " shrinking:" " min_heap_size: %6.1fK" " maximum_desired_capacity: %6.1fK" " shrink_bytes: %6.1fK", (double) min_heap_size / (double) K, (double) maximum_desired_capacity / (double) K, (double) shrink_bytes / (double) K); } } } HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, bool* succeeded) { assert_at_safepoint(true /* should_be_vm_thread */); *succeeded = true; // Let's attempt the allocation first. HeapWord* result = attempt_allocation_at_safepoint(word_size, false /* expect_null_cur_alloc_region */); if (result != NULL) { assert(*succeeded, "sanity"); return result; } // In a G1 heap, we're supposed to keep allocation from failing by // incremental pauses. Therefore, at least for now, we'll favor // expansion over collection. (This might change in the future if we can // do something smarter than full collection to satisfy a failed alloc.) result = expand_and_allocate(word_size); if (result != NULL) { assert(*succeeded, "sanity"); return result; } // Expansion didn't work, we'll try to do a Full GC. bool gc_succeeded = do_collection(false, /* explicit_gc */ false, /* clear_all_soft_refs */ word_size); if (!gc_succeeded) { *succeeded = false; return NULL; } // Retry the allocation result = attempt_allocation_at_safepoint(word_size, true /* expect_null_cur_alloc_region */); if (result != NULL) { assert(*succeeded, "sanity"); return result; } // Then, try a Full GC that will collect all soft references. gc_succeeded = do_collection(false, /* explicit_gc */ true, /* clear_all_soft_refs */ word_size); if (!gc_succeeded) { *succeeded = false; return NULL; } // Retry the allocation once more result = attempt_allocation_at_safepoint(word_size, true /* expect_null_cur_alloc_region */); if (result != NULL) { assert(*succeeded, "sanity"); return result; } assert(!collector_policy()->should_clear_all_soft_refs(), "Flag should have been handled and cleared prior to this point"); // What else? We might try synchronous finalization later. If the total // space available is large enough for the allocation, then a more // complete compaction phase than we've tried so far might be // appropriate. assert(*succeeded, "sanity"); return NULL; } // Attempting to expand the heap sufficiently // to support an allocation of the given "word_size". If // successful, perform the allocation and return the address of the // allocated block, or else "NULL". HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { assert_at_safepoint(true /* should_be_vm_thread */); verify_region_sets_optional(); size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); if (expand(expand_bytes)) { verify_region_sets_optional(); return attempt_allocation_at_safepoint(word_size, false /* expect_null_cur_alloc_region */); } return NULL; } bool G1CollectedHeap::expand(size_t expand_bytes) { size_t old_mem_size = _g1_storage.committed_size(); size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); aligned_expand_bytes = align_size_up(aligned_expand_bytes, HeapRegion::GrainBytes); if (Verbose && PrintGC) { gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK", old_mem_size/K, aligned_expand_bytes/K); } HeapWord* old_end = (HeapWord*)_g1_storage.high(); bool successful = _g1_storage.expand_by(aligned_expand_bytes); if (successful) { HeapWord* new_end = (HeapWord*)_g1_storage.high(); // Expand the committed region. _g1_committed.set_end(new_end); // Tell the cardtable about the expansion. Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); // And the offset table as well. _bot_shared->resize(_g1_committed.word_size()); expand_bytes = aligned_expand_bytes; HeapWord* base = old_end; // Create the heap regions for [old_end, new_end) while (expand_bytes > 0) { HeapWord* high = base + HeapRegion::GrainWords; // Create a new HeapRegion. MemRegion mr(base, high); bool is_zeroed = !_g1_max_committed.contains(base); HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed); // Add it to the HeapRegionSeq. _hrs->insert(hr); _free_list.add_as_tail(hr); // And we used up an expansion region to create it. _expansion_regions--; expand_bytes -= HeapRegion::GrainBytes; base += HeapRegion::GrainWords; } assert(base == new_end, "sanity"); // Now update max_committed if necessary. _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), new_end)); } else { // The expansion of the virtual storage space was unsuccessful. // Let's see if it was because we ran out of swap. if (G1ExitOnExpansionFailure && _g1_storage.uncommitted_size() >= aligned_expand_bytes) { // We had head room... vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion"); } } if (Verbose && PrintGC) { size_t new_mem_size = _g1_storage.committed_size(); gclog_or_tty->print_cr("...%s, expanded to %ldK", (successful ? "Successful" : "Failed"), new_mem_size/K); } return successful; } void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { size_t old_mem_size = _g1_storage.committed_size(); size_t aligned_shrink_bytes = ReservedSpace::page_align_size_down(shrink_bytes); aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, HeapRegion::GrainBytes); size_t num_regions_deleted = 0; MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted); assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!"); if (mr.byte_size() > 0) _g1_storage.shrink_by(mr.byte_size()); assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!"); _g1_committed.set_end(mr.start()); _expansion_regions += num_regions_deleted; // Tell the cardtable about it. Universe::heap()->barrier_set()->resize_covered_region(_g1_committed); // And the offset table as well. _bot_shared->resize(_g1_committed.word_size()); HeapRegionRemSet::shrink_heap(n_regions()); if (Verbose && PrintGC) { size_t new_mem_size = _g1_storage.committed_size(); gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK", old_mem_size/K, aligned_shrink_bytes/K, new_mem_size/K); } } void G1CollectedHeap::shrink(size_t shrink_bytes) { verify_region_sets_optional(); release_gc_alloc_regions(true /* totally */); // Instead of tearing down / rebuilding the free lists here, we // could instead use the remove_all_pending() method on free_list to // remove only the ones that we need to remove. tear_down_region_lists(); // We will rebuild them in a moment. shrink_helper(shrink_bytes); rebuild_region_lists(); verify_region_sets_optional(); } // Public methods. #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away #pragma warning( disable:4355 ) // 'this' : used in base member initializer list #endif // _MSC_VER G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : SharedHeap(policy_), _g1_policy(policy_), _dirty_card_queue_set(false), _into_cset_dirty_card_queue_set(false), _is_alive_closure(this), _ref_processor(NULL), _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), _bot_shared(NULL), _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL), _evac_failure_scan_stack(NULL) , _mark_in_progress(false), _cg1r(NULL), _summary_bytes_used(0), _cur_alloc_region(NULL), _refine_cte_cl(NULL), _full_collection(false), _free_list("Master Free List"), _secondary_free_list("Secondary Free List"), _humongous_set("Master Humongous Set"), _free_regions_coming(false), _young_list(new YoungList(this)), _gc_time_stamp(0), _surviving_young_words(NULL), _full_collections_completed(0), _in_cset_fast_test(NULL), _in_cset_fast_test_base(NULL), _dirty_cards_region_list(NULL) { _g1h = this; // To catch bugs. if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { vm_exit_during_initialization("Failed necessary allocation."); } _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; int n_queues = MAX2((int)ParallelGCThreads, 1); _task_queues = new RefToScanQueueSet(n_queues); int n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); assert(n_rem_sets > 0, "Invariant."); HeapRegionRemSetIterator** iter_arr = NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues); for (int i = 0; i < n_queues; i++) { iter_arr[i] = new HeapRegionRemSetIterator(); } _rem_set_iterator = iter_arr; for (int i = 0; i < n_queues; i++) { RefToScanQueue* q = new RefToScanQueue(); q->initialize(); _task_queues->register_queue(i, q); } for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { _gc_alloc_regions[ap] = NULL; _gc_alloc_region_counts[ap] = 0; _retained_gc_alloc_regions[ap] = NULL; // by default, we do not retain a GC alloc region for each ap; // we'll override this, when appropriate, below _retain_gc_alloc_region[ap] = false; } // We will try to remember the last half-full tenured region we // allocated to at the end of a collection so that we can re-use it // during the next collection. _retain_gc_alloc_region[GCAllocForTenured] = true; guarantee(_task_queues != NULL, "task_queues allocation failure."); } jint G1CollectedHeap::initialize() { CollectedHeap::pre_initialize(); os::enable_vtime(); // Necessary to satisfy locking discipline assertions. MutexLocker x(Heap_lock); // While there are no constraints in the GC code that HeapWordSize // be any particular value, there are multiple other areas in the // system which believe this to be true (e.g. oop->object_size in some // cases incorrectly returns the size in wordSize units rather than // HeapWordSize). guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); size_t init_byte_size = collector_policy()->initial_heap_byte_size(); size_t max_byte_size = collector_policy()->max_heap_byte_size(); // Ensure that the sizes are properly aligned. Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); _cg1r = new ConcurrentG1Refine(); // Reserve the maximum. PermanentGenerationSpec* pgs = collector_policy()->permanent_generation(); // Includes the perm-gen. const size_t total_reserved = max_byte_size + pgs->max_size(); char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop); ReservedSpace heap_rs(max_byte_size + pgs->max_size(), HeapRegion::GrainBytes, UseLargePages, addr); if (UseCompressedOops) { if (addr != NULL && !heap_rs.is_reserved()) { // Failed to reserve at specified address - the requested memory // region is taken already, for example, by 'java' launcher. // Try again to reserver heap higher. addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop); ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes, UseLargePages, addr); if (addr != NULL && !heap_rs0.is_reserved()) { // Failed to reserve at specified address again - give up. addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop); assert(addr == NULL, ""); ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes, UseLargePages, addr); heap_rs = heap_rs1; } else { heap_rs = heap_rs0; } } } if (!heap_rs.is_reserved()) { vm_exit_during_initialization("Could not reserve enough space for object heap"); return JNI_ENOMEM; } // It is important to do this in a way such that concurrent readers can't // temporarily think somethings in the heap. (I've actually seen this // happen in asserts: DLD.) _reserved.set_word_size(0); _reserved.set_start((HeapWord*)heap_rs.base()); _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size())); _expansion_regions = max_byte_size/HeapRegion::GrainBytes; // Create the gen rem set (and barrier set) for the entire reserved region. _rem_set = collector_policy()->create_rem_set(_reserved, 2); set_barrier_set(rem_set()->bs()); if (barrier_set()->is_a(BarrierSet::ModRef)) { _mr_bs = (ModRefBarrierSet*)_barrier_set; } else { vm_exit_during_initialization("G1 requires a mod ref bs."); return JNI_ENOMEM; } // Also create a G1 rem set. if (mr_bs()->is_a(BarrierSet::CardTableModRef)) { _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs()); } else { vm_exit_during_initialization("G1 requires a cardtable mod ref bs."); return JNI_ENOMEM; } // Carve out the G1 part of the heap. ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); _g1_reserved = MemRegion((HeapWord*)g1_rs.base(), g1_rs.size()/HeapWordSize); ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size); _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set()); _g1_storage.initialize(g1_rs, 0); _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0); _g1_max_committed = _g1_committed; _hrs = new HeapRegionSeq(_expansion_regions); guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq"); guarantee(_cur_alloc_region == NULL, "from constructor"); // 6843694 - ensure that the maximum region index can fit // in the remembered set structures. const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region, "too many cards per region"); HeapRegionSet::set_unrealistically_long_length(max_regions() + 1); _bot_shared = new G1BlockOffsetSharedArray(_reserved, heap_word_size(init_byte_size)); _g1h = this; _in_cset_fast_test_length = max_regions(); _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length); // We're biasing _in_cset_fast_test to avoid subtracting the // beginning of the heap every time we want to index; basically // it's the same with what we do with the card table. _in_cset_fast_test = _in_cset_fast_test_base - ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes); // Clear the _cset_fast_test bitmap in anticipation of adding // regions to the incremental collection set for the first // evacuation pause. clear_cset_fast_test(); // Create the ConcurrentMark data structure and thread. // (Must do this late, so that "max_regions" is defined.) _cm = new ConcurrentMark(heap_rs, (int) max_regions()); _cmThread = _cm->cmThread(); // Initialize the from_card cache structure of HeapRegionRemSet. HeapRegionRemSet::init_heap(max_regions()); // Now expand into the initial heap size. if (!expand(init_byte_size)) { vm_exit_during_initialization("Failed to allocate initial heap."); return JNI_ENOMEM; } // Perform any initialization actions delegated to the policy. g1_policy()->init(); g1_policy()->note_start_of_mark_thread(); _refine_cte_cl = new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(), g1_rem_set(), concurrent_g1_refine()); JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl); JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, SATB_Q_FL_lock, G1SATBProcessCompletedThreshold, Shared_SATB_Q_lock); JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, DirtyCardQ_FL_lock, concurrent_g1_refine()->yellow_zone(), concurrent_g1_refine()->red_zone(), Shared_DirtyCardQ_lock); if (G1DeferredRSUpdate) { dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, DirtyCardQ_FL_lock, -1, // never trigger processing -1, // no limit on length Shared_DirtyCardQ_lock, &JavaThread::dirty_card_queue_set()); } // Initialize the card queue set used to hold cards containing // references into the collection set. _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon, DirtyCardQ_FL_lock, -1, // never trigger processing -1, // no limit on length Shared_DirtyCardQ_lock, &JavaThread::dirty_card_queue_set()); // In case we're keeping closure specialization stats, initialize those // counts and that mechanism. SpecializationStats::clear(); _gc_alloc_region_list = NULL; // Do later initialization work for concurrent refinement. _cg1r->init(); return JNI_OK; } void G1CollectedHeap::ref_processing_init() { // Reference processing in G1 currently works as follows: // // * There is only one reference processor instance that // 'spans' the entire heap. It is created by the code // below. // * Reference discovery is not enabled during an incremental // pause (see 6484982). // * Discoverered refs are not enqueued nor are they processed // during an incremental pause (see 6484982). // * Reference discovery is enabled at initial marking. // * Reference discovery is disabled and the discovered // references processed etc during remarking. // * Reference discovery is MT (see below). // * Reference discovery requires a barrier (see below). // * Reference processing is currently not MT (see 6608385). // * A full GC enables (non-MT) reference discovery and // processes any discovered references. SharedHeap::ref_processing_init(); MemRegion mr = reserved_region(); _ref_processor = new ReferenceProcessor(mr, // span ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing (int) ParallelGCThreads, // degree of mt processing ParallelGCThreads > 1 || ConcGCThreads > 1, // mt discovery (int) MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery false, // Reference discovery is not atomic &_is_alive_closure, // is alive closure for efficiency true); // Setting next fields of discovered // lists requires a barrier. } size_t G1CollectedHeap::capacity() const { return _g1_committed.byte_size(); } void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, DirtyCardQueue* into_cset_dcq, bool concurrent, int worker_i) { // Clean cards in the hot card cache concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq); DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); int n_completed_buffers = 0; while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { n_completed_buffers++; } g1_policy()->record_update_rs_processed_buffers(worker_i, (double) n_completed_buffers); dcqs.clear_n_completed_buffers(); assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); } // Computes the sum of the storage used by the various regions. size_t G1CollectedHeap::used() const { assert(Heap_lock->owner() != NULL, "Should be owned on this thread's behalf."); size_t result = _summary_bytes_used; // Read only once in case it is set to NULL concurrently HeapRegion* hr = _cur_alloc_region; if (hr != NULL) result += hr->used(); return result; } size_t G1CollectedHeap::used_unlocked() const { size_t result = _summary_bytes_used; return result; } class SumUsedClosure: public HeapRegionClosure { size_t _used; public: SumUsedClosure() : _used(0) {} bool doHeapRegion(HeapRegion* r) { if (!r->continuesHumongous()) { _used += r->used(); } return false; } size_t result() { return _used; } }; size_t G1CollectedHeap::recalculate_used() const { SumUsedClosure blk; _hrs->iterate(&blk); return blk.result(); } #ifndef PRODUCT class SumUsedRegionsClosure: public HeapRegionClosure { size_t _num; public: SumUsedRegionsClosure() : _num(0) {} bool doHeapRegion(HeapRegion* r) { if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) { _num += 1; } return false; } size_t result() { return _num; } }; size_t G1CollectedHeap::recalculate_used_regions() const { SumUsedRegionsClosure blk; _hrs->iterate(&blk); return blk.result(); } #endif // PRODUCT size_t G1CollectedHeap::unsafe_max_alloc() { if (free_regions() > 0) return HeapRegion::GrainBytes; // otherwise, is there space in the current allocation region? // We need to store the current allocation region in a local variable // here. The problem is that this method doesn't take any locks and // there may be other threads which overwrite the current allocation // region field. attempt_allocation(), for example, sets it to NULL // and this can happen *after* the NULL check here but before the call // to free(), resulting in a SIGSEGV. Note that this doesn't appear // to be a problem in the optimized build, since the two loads of the // current allocation region field are optimized away. HeapRegion* car = _cur_alloc_region; // FIXME: should iterate over all regions? if (car == NULL) { return 0; } return car->free(); } bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { return ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)); } void G1CollectedHeap::increment_full_collections_completed(bool concurrent) { MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); // We assume that if concurrent == true, then the caller is a // concurrent thread that was joined the Suspendible Thread // Set. If there's ever a cheap way to check this, we should add an // assert here. // We have already incremented _total_full_collections at the start // of the GC, so total_full_collections() represents how many full // collections have been started. unsigned int full_collections_started = total_full_collections(); // Given that this method is called at the end of a Full GC or of a // concurrent cycle, and those can be nested (i.e., a Full GC can // interrupt a concurrent cycle), the number of full collections // completed should be either one (in the case where there was no // nesting) or two (when a Full GC interrupted a concurrent cycle) // behind the number of full collections started. // This is the case for the inner caller, i.e. a Full GC. assert(concurrent || (full_collections_started == _full_collections_completed + 1) || (full_collections_started == _full_collections_completed + 2), err_msg("for inner caller (Full GC): full_collections_started = %u " "is inconsistent with _full_collections_completed = %u", full_collections_started, _full_collections_completed)); // This is the case for the outer caller, i.e. the concurrent cycle. assert(!concurrent || (full_collections_started == _full_collections_completed + 1), err_msg("for outer caller (concurrent cycle): " "full_collections_started = %u " "is inconsistent with _full_collections_completed = %u", full_collections_started, _full_collections_completed)); _full_collections_completed += 1; // We need to clear the "in_progress" flag in the CM thread before // we wake up any waiters (especially when ExplicitInvokesConcurrent // is set) so that if a waiter requests another System.gc() it doesn't // incorrectly see that a marking cyle is still in progress. if (concurrent) { _cmThread->clear_in_progress(); } // This notify_all() will ensure that a thread that called // System.gc() with (with ExplicitGCInvokesConcurrent set or not) // and it's waiting for a full GC to finish will be woken up. It is // waiting in VM_G1IncCollectionPause::doit_epilogue(). FullGCCount_lock->notify_all(); } void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { assert_at_safepoint(true /* should_be_vm_thread */); GCCauseSetter gcs(this, cause); switch (cause) { case GCCause::_heap_inspection: case GCCause::_heap_dump: { HandleMark hm; do_full_collection(false); // don't clear all soft refs break; } default: // XXX FIX ME ShouldNotReachHere(); // Unexpected use of this function } } void G1CollectedHeap::collect(GCCause::Cause cause) { // The caller doesn't have the Heap_lock assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); unsigned int gc_count_before; unsigned int full_gc_count_before; { MutexLocker ml(Heap_lock); // Read the GC count while holding the Heap_lock gc_count_before = SharedHeap::heap()->total_collections(); full_gc_count_before = SharedHeap::heap()->total_full_collections(); } if (should_do_concurrent_full_gc(cause)) { // Schedule an initial-mark evacuation pause that will start a // concurrent cycle. We're setting word_size to 0 which means that // we are not requesting a post-GC allocation. VM_G1IncCollectionPause op(gc_count_before, 0, /* word_size */ true, /* should_initiate_conc_mark */ g1_policy()->max_pause_time_ms(), cause); VMThread::execute(&op); } else { if (cause == GCCause::_gc_locker DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { // Schedule a standard evacuation pause. We're setting word_size // to 0 which means that we are not requesting a post-GC allocation. VM_G1IncCollectionPause op(gc_count_before, 0, /* word_size */ false, /* should_initiate_conc_mark */ g1_policy()->max_pause_time_ms(), cause); VMThread::execute(&op); } else { // Schedule a Full GC. VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); VMThread::execute(&op); } } } bool G1CollectedHeap::is_in(const void* p) const { if (_g1_committed.contains(p)) { HeapRegion* hr = _hrs->addr_to_region(p); return hr->is_in(p); } else { return _perm_gen->as_gen()->is_in(p); } } // Iteration functions. // Iterates an OopClosure over all ref-containing fields of objects // within a HeapRegion. class IterateOopClosureRegionClosure: public HeapRegionClosure { MemRegion _mr; OopClosure* _cl; public: IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl) : _mr(mr), _cl(cl) {} bool doHeapRegion(HeapRegion* r) { if (! r->continuesHumongous()) { r->oop_iterate(_cl); } return false; } }; void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) { IterateOopClosureRegionClosure blk(_g1_committed, cl); _hrs->iterate(&blk); if (do_perm) { perm_gen()->oop_iterate(cl); } } void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) { IterateOopClosureRegionClosure blk(mr, cl); _hrs->iterate(&blk); if (do_perm) { perm_gen()->oop_iterate(cl); } } // Iterates an ObjectClosure over all objects within a HeapRegion. class IterateObjectClosureRegionClosure: public HeapRegionClosure { ObjectClosure* _cl; public: IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} bool doHeapRegion(HeapRegion* r) { if (! r->continuesHumongous()) { r->object_iterate(_cl); } return false; } }; void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) { IterateObjectClosureRegionClosure blk(cl); _hrs->iterate(&blk); if (do_perm) { perm_gen()->object_iterate(cl); } } void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) { // FIXME: is this right? guarantee(false, "object_iterate_since_last_GC not supported by G1 heap"); } // Calls a SpaceClosure on a HeapRegion. class SpaceClosureRegionClosure: public HeapRegionClosure { SpaceClosure* _cl; public: SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {} bool doHeapRegion(HeapRegion* r) { _cl->do_space(r); return false; } }; void G1CollectedHeap::space_iterate(SpaceClosure* cl) { SpaceClosureRegionClosure blk(cl); _hrs->iterate(&blk); } void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) { _hrs->iterate(cl); } void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* cl) { _hrs->iterate_from(r, cl); } void G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) { _hrs->iterate_from(idx, cl); } HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); } void G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl, int worker, jint claim_value) { const size_t regions = n_regions(); const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1); // try to spread out the starting points of the workers const size_t start_index = regions / worker_num * (size_t) worker; // each worker will actually look at all regions for (size_t count = 0; count < regions; ++count) { const size_t index = (start_index + count) % regions; assert(0 <= index && index < regions, "sanity"); HeapRegion* r = region_at(index); // we'll ignore "continues humongous" regions (we'll process them // when we come across their corresponding "start humongous" // region) and regions already claimed if (r->claim_value() == claim_value || r->continuesHumongous()) { continue; } // OK, try to claim it if (r->claimHeapRegion(claim_value)) { // success! assert(!r->continuesHumongous(), "sanity"); if (r->startsHumongous()) { // If the region is "starts humongous" we'll iterate over its // "continues humongous" first; in fact we'll do them // first. The order is important. In on case, calling the // closure on the "starts humongous" region might de-allocate // and clear all its "continues humongous" regions and, as a // result, we might end up processing them twice. So, we'll do // them first (notice: most closures will ignore them anyway) and // then we'll do the "starts humongous" region. for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) { HeapRegion* chr = region_at(ch_index); // if the region has already been claimed or it's not // "continues humongous" we're done if (chr->claim_value() == claim_value || !chr->continuesHumongous()) { break; } // Noone should have claimed it directly. We can given // that we claimed its "starts humongous" region. assert(chr->claim_value() != claim_value, "sanity"); assert(chr->humongous_start_region() == r, "sanity"); if (chr->claimHeapRegion(claim_value)) { // we should always be able to claim it; noone else should // be trying to claim this region bool res2 = cl->doHeapRegion(chr); assert(!res2, "Should not abort"); // Right now, this holds (i.e., no closure that actually // does something with "continues humongous" regions // clears them). We might have to weaken it in the future, // but let's leave these two asserts here for extra safety. assert(chr->continuesHumongous(), "should still be the case"); assert(chr->humongous_start_region() == r, "sanity"); } else { guarantee(false, "we should not reach here"); } } } assert(!r->continuesHumongous(), "sanity"); bool res = cl->doHeapRegion(r); assert(!res, "Should not abort"); } } } class ResetClaimValuesClosure: public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* r) { r->set_claim_value(HeapRegion::InitialClaimValue); return false; } }; void G1CollectedHeap::reset_heap_region_claim_values() { ResetClaimValuesClosure blk; heap_region_iterate(&blk); } #ifdef ASSERT // This checks whether all regions in the heap have the correct claim // value. I also piggy-backed on this a check to ensure that the // humongous_start_region() information on "continues humongous" // regions is correct. class CheckClaimValuesClosure : public HeapRegionClosure { private: jint _claim_value; size_t _failures; HeapRegion* _sh_region; public: CheckClaimValuesClosure(jint claim_value) : _claim_value(claim_value), _failures(0), _sh_region(NULL) { } bool doHeapRegion(HeapRegion* r) { if (r->claim_value() != _claim_value) { gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), " "claim value = %d, should be %d", r->bottom(), r->end(), r->claim_value(), _claim_value); ++_failures; } if (!r->isHumongous()) { _sh_region = NULL; } else if (r->startsHumongous()) { _sh_region = r; } else if (r->continuesHumongous()) { if (r->humongous_start_region() != _sh_region) { gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), " "HS = "PTR_FORMAT", should be "PTR_FORMAT, r->bottom(), r->end(), r->humongous_start_region(), _sh_region); ++_failures; } } return false; } size_t failures() { return _failures; } }; bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) { CheckClaimValuesClosure cl(claim_value); heap_region_iterate(&cl); return cl.failures() == 0; } #endif // ASSERT void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { HeapRegion* r = g1_policy()->collection_set(); while (r != NULL) { HeapRegion* next = r->next_in_collection_set(); if (cl->doHeapRegion(r)) { cl->incomplete(); return; } r = next; } } void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *cl) { if (r == NULL) { // The CSet is empty so there's nothing to do. return; } assert(r->in_collection_set(), "Start region must be a member of the collection set."); HeapRegion* cur = r; while (cur != NULL) { HeapRegion* next = cur->next_in_collection_set(); if (cl->doHeapRegion(cur) && false) { cl->incomplete(); return; } cur = next; } cur = g1_policy()->collection_set(); while (cur != r) { HeapRegion* next = cur->next_in_collection_set(); if (cl->doHeapRegion(cur) && false) { cl->incomplete(); return; } cur = next; } } CompactibleSpace* G1CollectedHeap::first_compactible_space() { return _hrs->length() > 0 ? _hrs->at(0) : NULL; } Space* G1CollectedHeap::space_containing(const void* addr) const { Space* res = heap_region_containing(addr); if (res == NULL) res = perm_gen()->space_containing(addr); return res; } HeapWord* G1CollectedHeap::block_start(const void* addr) const { Space* sp = space_containing(addr); if (sp != NULL) { return sp->block_start(addr); } return NULL; } size_t G1CollectedHeap::block_size(const HeapWord* addr) const { Space* sp = space_containing(addr); assert(sp != NULL, "block_size of address outside of heap"); return sp->block_size(addr); } bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { Space* sp = space_containing(addr); return sp->block_is_obj(addr); } bool G1CollectedHeap::supports_tlab_allocation() const { return true; } size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { return HeapRegion::GrainBytes; } size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { // Return the remaining space in the cur alloc region, but not less than // the min TLAB size. // Also, this value can be at most the humongous object threshold, // since we can't allow tlabs to grow big enough to accomodate // humongous objects. // We need to store the cur alloc region locally, since it might change // between when we test for NULL and when we use it later. ContiguousSpace* cur_alloc_space = _cur_alloc_region; size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize; if (cur_alloc_space == NULL) { return max_tlab_size; } else { return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize), max_tlab_size); } } size_t G1CollectedHeap::large_typearray_limit() { // FIXME return HeapRegion::GrainBytes/HeapWordSize; } size_t G1CollectedHeap::max_capacity() const { return _g1_reserved.byte_size(); } jlong G1CollectedHeap::millis_since_last_gc() { // assert(false, "NYI"); return 0; } void G1CollectedHeap::prepare_for_verify() { if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { ensure_parsability(false); } g1_rem_set()->prepare_for_verify(); } class VerifyLivenessOopClosure: public OopClosure { G1CollectedHeap* g1h; public: VerifyLivenessOopClosure(G1CollectedHeap* _g1h) { g1h = _g1h; } void do_oop(narrowOop *p) { do_oop_work(p); } void do_oop( oop *p) { do_oop_work(p); } template <class T> void do_oop_work(T *p) { oop obj = oopDesc::load_decode_heap_oop(p); guarantee(obj == NULL || !g1h->is_obj_dead(obj), "Dead object referenced by a not dead object"); } }; class VerifyObjsInRegionClosure: public ObjectClosure { private: G1CollectedHeap* _g1h; size_t _live_bytes; HeapRegion *_hr; bool _use_prev_marking; public: // use_prev_marking == true -> use "prev" marking information, // use_prev_marking == false -> use "next" marking information VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking) : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) { _g1h = G1CollectedHeap::heap(); } void do_object(oop o) { VerifyLivenessOopClosure isLive(_g1h); assert(o != NULL, "Huh?"); if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) { o->oop_iterate(&isLive); if (!_hr->obj_allocated_since_prev_marking(o)) { size_t obj_size = o->size(); // Make sure we don't overflow _live_bytes += (obj_size * HeapWordSize); } } } size_t live_bytes() { return _live_bytes; } }; class PrintObjsInRegionClosure : public ObjectClosure { HeapRegion *_hr; G1CollectedHeap *_g1; public: PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) { _g1 = G1CollectedHeap::heap(); }; void do_object(oop o) { if (o != NULL) { HeapWord *start = (HeapWord *) o; size_t word_sz = o->size(); gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n", (void*) o, word_sz, _g1->isMarkedPrev(o), _g1->isMarkedNext(o), _hr->obj_allocated_since_prev_marking(o)); HeapWord *end = start + word_sz; HeapWord *cur; int *val; for (cur = start; cur < end; cur++) { val = (int *) cur; gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val); } } } }; class VerifyRegionClosure: public HeapRegionClosure { private: bool _allow_dirty; bool _par; bool _use_prev_marking; bool _failures; public: // use_prev_marking == true -> use "prev" marking information, // use_prev_marking == false -> use "next" marking information VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking) : _allow_dirty(allow_dirty), _par(par), _use_prev_marking(use_prev_marking), _failures(false) {} bool failures() { return _failures; } bool doHeapRegion(HeapRegion* r) { guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue, "Should be unclaimed at verify points."); if (!r->continuesHumongous()) { bool failures = false; r->verify(_allow_dirty, _use_prev_marking, &failures); if (failures) { _failures = true; } else { VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking); r->object_iterate(¬_dead_yet_cl); if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " "max_live_bytes "SIZE_FORMAT" " "< calculated "SIZE_FORMAT, r->bottom(), r->end(), r->max_live_bytes(), not_dead_yet_cl.live_bytes()); _failures = true; } } } return false; // stop the region iteration if we hit a failure } }; class VerifyRootsClosure: public OopsInGenClosure { private: G1CollectedHeap* _g1h; bool _use_prev_marking; bool _failures; public: // use_prev_marking == true -> use "prev" marking information, // use_prev_marking == false -> use "next" marking information VerifyRootsClosure(bool use_prev_marking) : _g1h(G1CollectedHeap::heap()), _use_prev_marking(use_prev_marking), _failures(false) { } bool failures() { return _failures; } template <class T> void do_oop_nv(T* p) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) { gclog_or_tty->print_cr("Root location "PTR_FORMAT" " "points to dead obj "PTR_FORMAT, p, (void*) obj); obj->print_on(gclog_or_tty); _failures = true; } } } void do_oop(oop* p) { do_oop_nv(p); } void do_oop(narrowOop* p) { do_oop_nv(p); } }; // This is the task used for parallel heap verification. class G1ParVerifyTask: public AbstractGangTask { private: G1CollectedHeap* _g1h; bool _allow_dirty; bool _use_prev_marking; bool _failures; public: // use_prev_marking == true -> use "prev" marking information, // use_prev_marking == false -> use "next" marking information G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, bool use_prev_marking) : AbstractGangTask("Parallel verify task"), _g1h(g1h), _allow_dirty(allow_dirty), _use_prev_marking(use_prev_marking), _failures(false) { } bool failures() { return _failures; } void work(int worker_i) { HandleMark hm; VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking); _g1h->heap_region_par_iterate_chunked(&blk, worker_i, HeapRegion::ParVerifyClaimValue); if (blk.failures()) { _failures = true; } } }; void G1CollectedHeap::verify(bool allow_dirty, bool silent) { verify(allow_dirty, silent, /* use_prev_marking */ true); } void G1CollectedHeap::verify(bool allow_dirty, bool silent, bool use_prev_marking) { if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { if (!silent) { gclog_or_tty->print("roots "); } VerifyRootsClosure rootsCl(use_prev_marking); CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false); process_strong_roots(true, // activate StrongRootsScope false, SharedHeap::SO_AllClasses, &rootsCl, &blobsCl, &rootsCl); bool failures = rootsCl.failures(); rem_set()->invalidate(perm_gen()->used_region(), false); if (!silent) { gclog_or_tty->print("HeapRegionSets "); } verify_region_sets(); if (!silent) { gclog_or_tty->print("HeapRegions "); } if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity check"); G1ParVerifyTask task(this, allow_dirty, use_prev_marking); int n_workers = workers()->total_workers(); set_par_threads(n_workers); workers()->run_task(&task); set_par_threads(0); if (task.failures()) { failures = true; } assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue), "sanity check"); reset_heap_region_claim_values(); assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity check"); } else { VerifyRegionClosure blk(allow_dirty, false, use_prev_marking); _hrs->iterate(&blk); if (blk.failures()) { failures = true; } } if (!silent) gclog_or_tty->print("RemSet "); rem_set()->verify(); if (failures) { gclog_or_tty->print_cr("Heap:"); print_on(gclog_or_tty, true /* extended */); gclog_or_tty->print_cr(""); #ifndef PRODUCT if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) { concurrent_mark()->print_reachable("at-verification-failure", use_prev_marking, false /* all */); } #endif gclog_or_tty->flush(); } guarantee(!failures, "there should not have been any failures"); } else { if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) "); } } class PrintRegionClosure: public HeapRegionClosure { outputStream* _st; public: PrintRegionClosure(outputStream* st) : _st(st) {} bool doHeapRegion(HeapRegion* r) { r->print_on(_st); return false; } }; void G1CollectedHeap::print() const { print_on(tty); } void G1CollectedHeap::print_on(outputStream* st) const { print_on(st, PrintHeapAtGCExtended); } void G1CollectedHeap::print_on(outputStream* st, bool extended) const { st->print(" %-20s", "garbage-first heap"); st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", capacity()/K, used_unlocked()/K); st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", _g1_storage.low_boundary(), _g1_storage.high(), _g1_storage.high_boundary()); st->cr(); st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes/K); size_t young_regions = _young_list->length(); st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ", young_regions, young_regions * HeapRegion::GrainBytes / K); size_t survivor_regions = g1_policy()->recorded_survivor_regions(); st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)", survivor_regions, survivor_regions * HeapRegion::GrainBytes / K); st->cr(); perm()->as_gen()->print_on(st); if (extended) { st->cr(); print_on_extended(st); } } void G1CollectedHeap::print_on_extended(outputStream* st) const { PrintRegionClosure blk(st); _hrs->iterate(&blk); } void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { if (G1CollectedHeap::use_parallel_gc_threads()) { workers()->print_worker_threads_on(st); } _cmThread->print_on(st); st->cr(); _cm->print_worker_threads_on(st); _cg1r->print_worker_threads_on(st); st->cr(); } void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { if (G1CollectedHeap::use_parallel_gc_threads()) { workers()->threads_do(tc); } tc->do_thread(_cmThread); _cg1r->threads_do(tc); } void G1CollectedHeap::print_tracing_info() const { // We'll overload this to mean "trace GC pause statistics." if (TraceGen0Time || TraceGen1Time) { // The "G1CollectorPolicy" is keeping track of these stats, so delegate // to that. g1_policy()->print_tracing_info(); } if (G1SummarizeRSetStats) { g1_rem_set()->print_summary_info(); } if (G1SummarizeConcMark) { concurrent_mark()->print_summary_info(); } g1_policy()->print_yg_surv_rate_info(); SpecializationStats::print(); } int G1CollectedHeap::addr_to_arena_id(void* addr) const { HeapRegion* hr = heap_region_containing(addr); if (hr == NULL) { return 0; } else { return 1; } } G1CollectedHeap* G1CollectedHeap::heap() { assert(_sh->kind() == CollectedHeap::G1CollectedHeap, "not a garbage-first heap"); return _g1h; } void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { // always_do_update_barrier = false; assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); // Call allocation profiler AllocationProfiler::iterate_since_last_gc(); // Fill TLAB's and such ensure_parsability(true); } void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) { // FIXME: what is this about? // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" // is set. COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), "derived pointer present")); // always_do_update_barrier = true; } HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, unsigned int gc_count_before, bool* succeeded) { assert_heap_not_locked_and_not_at_safepoint(); g1_policy()->record_stop_world_start(); VM_G1IncCollectionPause op(gc_count_before, word_size, false, /* should_initiate_conc_mark */ g1_policy()->max_pause_time_ms(), GCCause::_g1_inc_collection_pause); VMThread::execute(&op); HeapWord* result = op.result(); bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); assert(result == NULL || ret_succeeded, "the result should be NULL if the VM did not succeed"); *succeeded = ret_succeeded; assert_heap_not_locked(); return result; } void G1CollectedHeap::doConcurrentMark() { MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); if (!_cmThread->in_progress()) { _cmThread->set_started(); CGC_lock->notify(); } } class VerifyMarkedObjsClosure: public ObjectClosure { G1CollectedHeap* _g1h; public: VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} void do_object(oop obj) { assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true, "markandsweep mark should agree with concurrent deadness"); } }; void G1CollectedHeap::checkConcurrentMark() { VerifyMarkedObjsClosure verifycl(this); // MutexLockerEx x(getMarkBitMapLock(), // Mutex::_no_safepoint_check_flag); object_iterate(&verifycl, false); } void G1CollectedHeap::do_sync_mark() { _cm->checkpointRootsInitial(); _cm->markFromRoots(); _cm->checkpointRootsFinal(false); } // <NEW PREDICTION> double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr, bool young) { return _g1_policy->predict_region_elapsed_time_ms(hr, young); } void G1CollectedHeap::check_if_region_is_too_expensive(double predicted_time_ms) { _g1_policy->check_if_region_is_too_expensive(predicted_time_ms); } size_t G1CollectedHeap::pending_card_num() { size_t extra_cards = 0; JavaThread *curr = Threads::first(); while (curr != NULL) { DirtyCardQueue& dcq = curr->dirty_card_queue(); extra_cards += dcq.size(); curr = curr->next(); } DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); size_t buffer_size = dcqs.buffer_size(); size_t buffer_num = dcqs.completed_buffers_num(); return buffer_size * buffer_num + extra_cards; } size_t G1CollectedHeap::max_pending_card_num() { DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); size_t buffer_size = dcqs.buffer_size(); size_t buffer_num = dcqs.completed_buffers_num(); int thread_num = Threads::number_of_threads(); return (buffer_num + thread_num) * buffer_size; } size_t G1CollectedHeap::cards_scanned() { return g1_rem_set()->cardsScanned(); } void G1CollectedHeap::setup_surviving_young_words() { guarantee( _surviving_young_words == NULL, "pre-condition" ); size_t array_length = g1_policy()->young_cset_length(); _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length); if (_surviving_young_words == NULL) { vm_exit_out_of_memory(sizeof(size_t) * array_length, "Not enough space for young surv words summary."); } memset(_surviving_young_words, 0, array_length * sizeof(size_t)); #ifdef ASSERT for (size_t i = 0; i < array_length; ++i) { assert( _surviving_young_words[i] == 0, "memset above" ); } #endif // !ASSERT } void G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); size_t array_length = g1_policy()->young_cset_length(); for (size_t i = 0; i < array_length; ++i) _surviving_young_words[i] += surv_young_words[i]; } void G1CollectedHeap::cleanup_surviving_young_words() { guarantee( _surviving_young_words != NULL, "pre-condition" ); FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); _surviving_young_words = NULL; } // </NEW PREDICTION> struct PrepareForRSScanningClosure : public HeapRegionClosure { bool doHeapRegion(HeapRegion *r) { r->rem_set()->set_iter_claimed(0); return false; } }; #if TASKQUEUE_STATS void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { st->print_raw_cr("GC Task Stats"); st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); } void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { print_taskqueue_stats_hdr(st); TaskQueueStats totals; const int n = workers() != NULL ? workers()->total_workers() : 1; for (int i = 0; i < n; ++i) { st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr(); totals += task_queue(i)->stats; } st->print_raw("tot "); totals.print(st); st->cr(); DEBUG_ONLY(totals.verify()); } void G1CollectedHeap::reset_taskqueue_stats() { const int n = workers() != NULL ? workers()->total_workers() : 1; for (int i = 0; i < n; ++i) { task_queue(i)->stats.reset(); } } #endif // TASKQUEUE_STATS bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { assert_at_safepoint(true /* should_be_vm_thread */); guarantee(!is_gc_active(), "collection is not reentrant"); if (GC_locker::check_active_before_gc()) { return false; } SvcGCMarker sgcm(SvcGCMarker::MINOR); ResourceMark rm; if (PrintHeapAtGC) { Universe::print_heap_before_gc(); } verify_region_sets_optional(); { // This call will decide whether this pause is an initial-mark // pause. If it is, during_initial_mark_pause() will return true // for the duration of this pause. g1_policy()->decide_on_conc_mark_initiation(); char verbose_str[128]; sprintf(verbose_str, "GC pause "); if (g1_policy()->in_young_gc_mode()) { if (g1_policy()->full_young_gcs()) strcat(verbose_str, "(young)"); else strcat(verbose_str, "(partial)"); } if (g1_policy()->during_initial_mark_pause()) { strcat(verbose_str, " (initial-mark)"); // We are about to start a marking cycle, so we increment the // full collection counter. increment_total_full_collections(); } // if PrintGCDetails is on, we'll print long statistics information // in the collector policy code, so let's not print this as the output // is messy if we do. gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty); TraceMemoryManagerStats tms(false /* fullGC */); // If the secondary_free_list is not empty, append it to the // free_list. No need to wait for the cleanup operation to finish; // the region allocation code will check the secondary_free_list // and wait if necessary. If the G1StressConcRegionFreeing flag is // set, skip this step so that the region allocation code has to // get entries from the secondary_free_list. if (!G1StressConcRegionFreeing) { append_secondary_free_list_if_not_empty_with_lock(); } increment_gc_time_stamp(); if (g1_policy()->in_young_gc_mode()) { assert(check_young_list_well_formed(), "young list should be well formed"); } { // Call to jvmpi::post_class_unload_events must occur outside of active GC IsGCActiveMark x; gc_prologue(false); increment_total_collections(false /* full gc */); #if G1_REM_SET_LOGGING gclog_or_tty->print_cr("\nJust chose CS, heap:"); print(); #endif if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification prepare_for_verify(); gclog_or_tty->print(" VerifyBeforeGC:"); Universe::verify(false); } COMPILER2_PRESENT(DerivedPointerTable::clear()); // Please see comment in G1CollectedHeap::ref_processing_init() // to see how reference processing currently works in G1. // // We want to turn off ref discovery, if necessary, and turn it back on // on again later if we do. XXX Dubious: why is discovery disabled? bool was_enabled = ref_processor()->discovery_enabled(); if (was_enabled) ref_processor()->disable_discovery(); // Forget the current alloc region (we might even choose it to be part // of the collection set!). abandon_cur_alloc_region(); // The elapsed time induced by the start time below deliberately elides // the possible verification above. double start_time_sec = os::elapsedTime(); size_t start_used_bytes = used(); #if YOUNG_LIST_VERBOSE gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); _young_list->print(); g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); #endif // YOUNG_LIST_VERBOSE g1_policy()->record_collection_pause_start(start_time_sec, start_used_bytes); #if YOUNG_LIST_VERBOSE gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); _young_list->print(); #endif // YOUNG_LIST_VERBOSE if (g1_policy()->during_initial_mark_pause()) { concurrent_mark()->checkpointRootsInitialPre(); } save_marks(); // We must do this before any possible evacuation that should propagate // marks. if (mark_in_progress()) { double start_time_sec = os::elapsedTime(); _cm->drainAllSATBBuffers(); double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0; g1_policy()->record_satb_drain_time(finish_mark_ms); } // Record the number of elements currently on the mark stack, so we // only iterate over these. (Since evacuation may add to the mark // stack, doing more exposes race conditions.) If no mark is in // progress, this will be zero. _cm->set_oops_do_bound(); if (mark_in_progress()) concurrent_mark()->newCSet(); #if YOUNG_LIST_VERBOSE gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); _young_list->print(); g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); #endif // YOUNG_LIST_VERBOSE g1_policy()->choose_collection_set(target_pause_time_ms); // Nothing to do if we were unable to choose a collection set. #if G1_REM_SET_LOGGING gclog_or_tty->print_cr("\nAfter pause, heap:"); print(); #endif PrepareForRSScanningClosure prepare_for_rs_scan; collection_set_iterate(&prepare_for_rs_scan); setup_surviving_young_words(); // Set up the gc allocation regions. get_gc_alloc_regions(); // Actually do the work... evacuate_collection_set(); free_collection_set(g1_policy()->collection_set()); g1_policy()->clear_collection_set(); cleanup_surviving_young_words(); // Start a new incremental collection set for the next pause. g1_policy()->start_incremental_cset_building(); // Clear the _cset_fast_test bitmap in anticipation of adding // regions to the incremental collection set for the next // evacuation pause. clear_cset_fast_test(); if (g1_policy()->in_young_gc_mode()) { _young_list->reset_sampled_info(); // Don't check the whole heap at this point as the // GC alloc regions from this pause have been tagged // as survivors and moved on to the survivor list. // Survivor regions will fail the !is_young() check. assert(check_young_list_empty(false /* check_heap */), "young list should be empty"); #if YOUNG_LIST_VERBOSE gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); _young_list->print(); #endif // YOUNG_LIST_VERBOSE g1_policy()->record_survivor_regions(_young_list->survivor_length(), _young_list->first_survivor_region(), _young_list->last_survivor_region()); _young_list->reset_auxilary_lists(); } if (evacuation_failed()) { _summary_bytes_used = recalculate_used(); } else { // The "used" of the the collection set have already been subtracted // when they were freed. Add in the bytes evacuated. _summary_bytes_used += g1_policy()->bytes_in_to_space(); } if (g1_policy()->in_young_gc_mode() && g1_policy()->during_initial_mark_pause()) { concurrent_mark()->checkpointRootsInitialPost(); set_marking_started(); // CAUTION: after the doConcurrentMark() call below, // the concurrent marking thread(s) could be running // concurrently with us. Make sure that anything after // this point does not assume that we are the only GC thread // running. Note: of course, the actual marking work will // not start until the safepoint itself is released in // ConcurrentGCThread::safepoint_desynchronize(). doConcurrentMark(); } #if YOUNG_LIST_VERBOSE gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); _young_list->print(); g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); #endif // YOUNG_LIST_VERBOSE double end_time_sec = os::elapsedTime(); double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS; g1_policy()->record_pause_time_ms(pause_time_ms); g1_policy()->record_collection_pause_end(); MemoryService::track_memory_usage(); if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification gclog_or_tty->print(" VerifyAfterGC:"); prepare_for_verify(); Universe::verify(false); } if (was_enabled) ref_processor()->enable_discovery(); { size_t expand_bytes = g1_policy()->expansion_amount(); if (expand_bytes > 0) { size_t bytes_before = capacity(); if (!expand(expand_bytes)) { // We failed to expand the heap so let's verify that // committed/uncommitted amount match the backing store assert(capacity() == _g1_storage.committed_size(), "committed size mismatch"); assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch"); } } } if (mark_in_progress()) { concurrent_mark()->update_g1_committed(); } #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif gc_epilogue(false); } if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) { gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum); print_tracing_info(); vm_exit(-1); } } verify_region_sets_optional(); TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats()); TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); if (PrintHeapAtGC) { Universe::print_heap_after_gc(); } if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { g1_rem_set()->print_summary_info(); } return true; } size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose) { size_t gclab_word_size; switch (purpose) { case GCAllocForSurvived: gclab_word_size = YoungPLABSize; break; case GCAllocForTenured: gclab_word_size = OldPLABSize; break; default: assert(false, "unknown GCAllocPurpose"); gclab_word_size = OldPLABSize; break; } return gclab_word_size; } void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) { assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose"); // make sure we don't call set_gc_alloc_region() multiple times on // the same region assert(r == NULL || !r->is_gc_alloc_region(), "shouldn't already be a GC alloc region"); assert(r == NULL || !r->isHumongous(), "humongous regions shouldn't be used as GC alloc regions"); HeapWord* original_top = NULL; if (r != NULL) original_top = r->top(); // We will want to record the used space in r as being there before gc. // One we install it as a GC alloc region it's eligible for allocation. // So record it now and use it later. size_t r_used = 0; if (r != NULL) { r_used = r->used(); if (G1CollectedHeap::use_parallel_gc_threads()) { // need to take the lock to guard against two threads calling // get_gc_alloc_region concurrently (very unlikely but...) MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); r->save_marks(); } } HeapRegion* old_alloc_region = _gc_alloc_regions[purpose]; _gc_alloc_regions[purpose] = r; if (old_alloc_region != NULL) { // Replace aliases too. for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { if (_gc_alloc_regions[ap] == old_alloc_region) { _gc_alloc_regions[ap] = r; } } } if (r != NULL) { push_gc_alloc_region(r); if (mark_in_progress() && original_top != r->next_top_at_mark_start()) { // We are using a region as a GC alloc region after it has been used // as a mutator allocation region during the current marking cycle. // The mutator-allocated objects are currently implicitly marked, but // when we move hr->next_top_at_mark_start() forward at the the end // of the GC pause, they won't be. We therefore mark all objects in // the "gap". We do this object-by-object, since marking densely // does not currently work right with marking bitmap iteration. This // means we rely on TLAB filling at the start of pauses, and no // "resuscitation" of filled TLAB's. If we want to do this, we need // to fix the marking bitmap iteration. HeapWord* curhw = r->next_top_at_mark_start(); HeapWord* t = original_top; while (curhw < t) { oop cur = (oop)curhw; // We'll assume parallel for generality. This is rare code. concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them? curhw = curhw + cur->size(); } assert(curhw == t, "Should have parsed correctly."); } if (G1PolicyVerbose > 1) { gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") " "for survivors:", r->bottom(), original_top, r->end()); r->print(); } g1_policy()->record_before_bytes(r_used); } } void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) { assert(Thread::current()->is_VM_thread() || FreeList_lock->owned_by_self(), "Precondition"); assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(), "Precondition."); hr->set_is_gc_alloc_region(true); hr->set_next_gc_alloc_region(_gc_alloc_region_list); _gc_alloc_region_list = hr; } #ifdef G1_DEBUG class FindGCAllocRegion: public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* r) { if (r->is_gc_alloc_region()) { gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.", r->hrs_index(), r->bottom()); } return false; } }; #endif // G1_DEBUG void G1CollectedHeap::forget_alloc_region_list() { assert_at_safepoint(true /* should_be_vm_thread */); while (_gc_alloc_region_list != NULL) { HeapRegion* r = _gc_alloc_region_list; assert(r->is_gc_alloc_region(), "Invariant."); // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on // newly allocated data in order to be able to apply deferred updates // before the GC is done for verification purposes (i.e to allow // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the // collection. r->ContiguousSpace::set_saved_mark(); _gc_alloc_region_list = r->next_gc_alloc_region(); r->set_next_gc_alloc_region(NULL); r->set_is_gc_alloc_region(false); if (r->is_survivor()) { if (r->is_empty()) { r->set_not_young(); } else { _young_list->add_survivor_region(r); } } } #ifdef G1_DEBUG FindGCAllocRegion fa; heap_region_iterate(&fa); #endif // G1_DEBUG } bool G1CollectedHeap::check_gc_alloc_regions() { // TODO: allocation regions check return true; } void G1CollectedHeap::get_gc_alloc_regions() { // First, let's check that the GC alloc region list is empty (it should) assert(_gc_alloc_region_list == NULL, "invariant"); for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { assert(_gc_alloc_regions[ap] == NULL, "invariant"); assert(_gc_alloc_region_counts[ap] == 0, "invariant"); // Create new GC alloc regions. HeapRegion* alloc_region = _retained_gc_alloc_regions[ap]; _retained_gc_alloc_regions[ap] = NULL; if (alloc_region != NULL) { assert(_retain_gc_alloc_region[ap], "only way to retain a GC region"); // let's make sure that the GC alloc region is not tagged as such // outside a GC operation assert(!alloc_region->is_gc_alloc_region(), "sanity"); if (alloc_region->in_collection_set() || alloc_region->top() == alloc_region->end() || alloc_region->top() == alloc_region->bottom() || alloc_region->isHumongous()) { // we will discard the current GC alloc region if // * it's in the collection set (it can happen!), // * it's already full (no point in using it), // * it's empty (this means that it was emptied during // a cleanup and it should be on the free list now), or // * it's humongous (this means that it was emptied // during a cleanup and was added to the free list, but // has been subseqently used to allocate a humongous // object that may be less than the region size). alloc_region = NULL; } } if (alloc_region == NULL) { // we will get a new GC alloc region alloc_region = new_gc_alloc_region(ap, HeapRegion::GrainWords); } else { // the region was retained from the last collection ++_gc_alloc_region_counts[ap]; if (G1PrintHeapRegions) { gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], " "top "PTR_FORMAT, alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top()); } } if (alloc_region != NULL) { assert(_gc_alloc_regions[ap] == NULL, "pre-condition"); set_gc_alloc_region(ap, alloc_region); } assert(_gc_alloc_regions[ap] == NULL || _gc_alloc_regions[ap]->is_gc_alloc_region(), "the GC alloc region should be tagged as such"); assert(_gc_alloc_regions[ap] == NULL || _gc_alloc_regions[ap] == _gc_alloc_region_list, "the GC alloc region should be the same as the GC alloc list head"); } // Set alternative regions for allocation purposes that have reached // their limit. for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap); if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) { _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose]; } } assert(check_gc_alloc_regions(), "alloc regions messed up"); } void G1CollectedHeap::release_gc_alloc_regions(bool totally) { // We keep a separate list of all regions that have been alloc regions in // the current collection pause. Forget that now. This method will // untag the GC alloc regions and tear down the GC alloc region // list. It's desirable that no regions are tagged as GC alloc // outside GCs. forget_alloc_region_list(); // The current alloc regions contain objs that have survived // collection. Make them no longer GC alloc regions. for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { HeapRegion* r = _gc_alloc_regions[ap]; _retained_gc_alloc_regions[ap] = NULL; _gc_alloc_region_counts[ap] = 0; if (r != NULL) { // we retain nothing on _gc_alloc_regions between GCs set_gc_alloc_region(ap, NULL); if (r->is_empty()) { // We didn't actually allocate anything in it; let's just put // it back on the free list. _free_list.add_as_tail(r); } else if (_retain_gc_alloc_region[ap] && !totally) { // retain it so that we can use it at the beginning of the next GC _retained_gc_alloc_regions[ap] = r; } } } } #ifndef PRODUCT // Useful for debugging void G1CollectedHeap::print_gc_alloc_regions() { gclog_or_tty->print_cr("GC alloc regions"); for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { HeapRegion* r = _gc_alloc_regions[ap]; if (r == NULL) { gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL); } else { gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT, ap, r->bottom(), r->used()); } } } #endif // PRODUCT void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { _drain_in_progress = false; set_evac_failure_closure(cl); _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true); } void G1CollectedHeap::finalize_for_evac_failure() { assert(_evac_failure_scan_stack != NULL && _evac_failure_scan_stack->length() == 0, "Postcondition"); assert(!_drain_in_progress, "Postcondition"); delete _evac_failure_scan_stack; _evac_failure_scan_stack = NULL; } // *** Sequential G1 Evacuation class G1IsAliveClosure: public BoolObjectClosure { G1CollectedHeap* _g1; public: G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} void do_object(oop p) { assert(false, "Do not call."); } bool do_object_b(oop p) { // It is reachable if it is outside the collection set, or is inside // and forwarded. #ifdef G1_DEBUG gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d", (void*) p, _g1->obj_in_cs(p), p->is_forwarded(), !_g1->obj_in_cs(p) || p->is_forwarded()); #endif // G1_DEBUG return !_g1->obj_in_cs(p) || p->is_forwarded(); } }; class G1KeepAliveClosure: public OopClosure { G1CollectedHeap* _g1; public: G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } void do_oop( oop* p) { oop obj = *p; #ifdef G1_DEBUG if (PrintGC && Verbose) { gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT, p, (void*) obj, (void*) *p); } #endif // G1_DEBUG if (_g1->obj_in_cs(obj)) { assert( obj->is_forwarded(), "invariant" ); *p = obj->forwardee(); #ifdef G1_DEBUG gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT, (void*) obj, (void*) *p); #endif // G1_DEBUG } } }; class UpdateRSetDeferred : public OopsInHeapRegionClosure { private: G1CollectedHeap* _g1; DirtyCardQueue *_dcq; CardTableModRefBS* _ct_bs; public: UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) : _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {} virtual void do_oop(narrowOop* p) { do_oop_work(p); } virtual void do_oop( oop* p) { do_oop_work(p); } template <class T> void do_oop_work(T* p) { assert(_from->is_in_reserved(p), "paranoia"); if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !_from->is_survivor()) { size_t card_index = _ct_bs->index_for(p); if (_ct_bs->mark_card_deferred(card_index)) { _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index)); } } } }; class RemoveSelfPointerClosure: public ObjectClosure { private: G1CollectedHeap* _g1; ConcurrentMark* _cm; HeapRegion* _hr; size_t _prev_marked_bytes; size_t _next_marked_bytes; OopsInHeapRegionClosure *_cl; public: RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr, OopsInHeapRegionClosure* cl) : _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0), _next_marked_bytes(0), _cl(cl) {} size_t prev_marked_bytes() { return _prev_marked_bytes; } size_t next_marked_bytes() { return _next_marked_bytes; } // <original comment> // The original idea here was to coalesce evacuated and dead objects. // However that caused complications with the block offset table (BOT). // In particular if there were two TLABs, one of them partially refined. // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~| // The BOT entries of the unrefined part of TLAB_2 point to the start // of TLAB_2. If the last object of the TLAB_1 and the first object // of TLAB_2 are coalesced, then the cards of the unrefined part // would point into middle of the filler object. // The current approach is to not coalesce and leave the BOT contents intact. // </original comment> // // We now reset the BOT when we start the object iteration over the // region and refine its entries for every object we come across. So // the above comment is not really relevant and we should be able // to coalesce dead objects if we want to. void do_object(oop obj) { HeapWord* obj_addr = (HeapWord*) obj; assert(_hr->is_in(obj_addr), "sanity"); size_t obj_size = obj->size(); _hr->update_bot_for_object(obj_addr, obj_size); if (obj->is_forwarded() && obj->forwardee() == obj) { // The object failed to move. assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs."); _cm->markPrev(obj); assert(_cm->isPrevMarked(obj), "Should be marked!"); _prev_marked_bytes += (obj_size * HeapWordSize); if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) { _cm->markAndGrayObjectIfNecessary(obj); } obj->set_mark(markOopDesc::prototype()); // While we were processing RSet buffers during the // collection, we actually didn't scan any cards on the // collection set, since we didn't want to update remebered // sets with entries that point into the collection set, given // that live objects fromthe collection set are about to move // and such entries will be stale very soon. This change also // dealt with a reliability issue which involved scanning a // card in the collection set and coming across an array that // was being chunked and looking malformed. The problem is // that, if evacuation fails, we might have remembered set // entries missing given that we skipped cards on the // collection set. So, we'll recreate such entries now. obj->oop_iterate(_cl); assert(_cm->isPrevMarked(obj), "Should be marked!"); } else { // The object has been either evacuated or is dead. Fill it with a // dummy object. MemRegion mr((HeapWord*)obj, obj_size); CollectedHeap::fill_with_object(mr); _cm->clearRangeBothMaps(mr); } } }; void G1CollectedHeap::remove_self_forwarding_pointers() { UpdateRSetImmediate immediate_update(_g1h->g1_rem_set()); DirtyCardQueue dcq(&_g1h->dirty_card_queue_set()); UpdateRSetDeferred deferred_update(_g1h, &dcq); OopsInHeapRegionClosure *cl; if (G1DeferredRSUpdate) { cl = &deferred_update; } else { cl = &immediate_update; } HeapRegion* cur = g1_policy()->collection_set(); while (cur != NULL) { assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!"); assert(!cur->isHumongous(), "sanity"); if (cur->evacuation_failed()) { assert(cur->in_collection_set(), "bad CS"); RemoveSelfPointerClosure rspc(_g1h, cur, cl); cur->reset_bot(); cl->set_region(cur); cur->object_iterate(&rspc); // A number of manipulations to make the TAMS be the current top, // and the marked bytes be the ones observed in the iteration. if (_g1h->concurrent_mark()->at_least_one_mark_complete()) { // The comments below are the postconditions achieved by the // calls. Note especially the last such condition, which says that // the count of marked bytes has been properly restored. cur->note_start_of_marking(false); // _next_top_at_mark_start == top, _next_marked_bytes == 0 cur->add_to_marked_bytes(rspc.prev_marked_bytes()); // _next_marked_bytes == prev_marked_bytes. cur->note_end_of_marking(); // _prev_top_at_mark_start == top(), // _prev_marked_bytes == prev_marked_bytes } // If there is no mark in progress, we modified the _next variables // above needlessly, but harmlessly. if (_g1h->mark_in_progress()) { cur->note_start_of_marking(false); // _next_top_at_mark_start == top, _next_marked_bytes == 0 // _next_marked_bytes == next_marked_bytes. } // Now make sure the region has the right index in the sorted array. g1_policy()->note_change_in_marked_bytes(cur); } cur = cur->next_in_collection_set(); } assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!"); // Now restore saved marks, if any. if (_objs_with_preserved_marks != NULL) { assert(_preserved_marks_of_objs != NULL, "Both or none."); guarantee(_objs_with_preserved_marks->length() == _preserved_marks_of_objs->length(), "Both or none."); for (int i = 0; i < _objs_with_preserved_marks->length(); i++) { oop obj = _objs_with_preserved_marks->at(i); markOop m = _preserved_marks_of_objs->at(i); obj->set_mark(m); } // Delete the preserved marks growable arrays (allocated on the C heap). delete _objs_with_preserved_marks; delete _preserved_marks_of_objs; _objs_with_preserved_marks = NULL; _preserved_marks_of_objs = NULL; } } void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { _evac_failure_scan_stack->push(obj); } void G1CollectedHeap::drain_evac_failure_scan_stack() { assert(_evac_failure_scan_stack != NULL, "precondition"); while (_evac_failure_scan_stack->length() > 0) { oop obj = _evac_failure_scan_stack->pop(); _evac_failure_closure->set_region(heap_region_containing(obj)); obj->oop_iterate_backwards(_evac_failure_closure); } } oop G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop old) { markOop m = old->mark(); oop forward_ptr = old->forward_to_atomic(old); if (forward_ptr == NULL) { // Forward-to-self succeeded. if (_evac_failure_closure != cl) { MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); assert(!_drain_in_progress, "Should only be true while someone holds the lock."); // Set the global evac-failure closure to the current thread's. assert(_evac_failure_closure == NULL, "Or locking has failed."); set_evac_failure_closure(cl); // Now do the common part. handle_evacuation_failure_common(old, m); // Reset to NULL. set_evac_failure_closure(NULL); } else { // The lock is already held, and this is recursive. assert(_drain_in_progress, "This should only be the recursive case."); handle_evacuation_failure_common(old, m); } return old; } else { // Someone else had a place to copy it. return forward_ptr; } } void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { set_evacuation_failed(true); preserve_mark_if_necessary(old, m); HeapRegion* r = heap_region_containing(old); if (!r->evacuation_failed()) { r->set_evacuation_failed(true); if (G1PrintHeapRegions) { gclog_or_tty->print("overflow in heap region "PTR_FORMAT" " "["PTR_FORMAT","PTR_FORMAT")\n", r, r->bottom(), r->end()); } } push_on_evac_failure_scan_stack(old); if (!_drain_in_progress) { // prevent recursion in copy_to_survivor_space() _drain_in_progress = true; drain_evac_failure_scan_stack(); _drain_in_progress = false; } } void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { assert(evacuation_failed(), "Oversaving!"); // We want to call the "for_promotion_failure" version only in the // case of a promotion failure. if (m->must_be_preserved_for_promotion_failure(obj)) { if (_objs_with_preserved_marks == NULL) { assert(_preserved_marks_of_objs == NULL, "Both or none."); _objs_with_preserved_marks = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true); _preserved_marks_of_objs = new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true); } _objs_with_preserved_marks->push(obj); _preserved_marks_of_objs->push(m); } } // *** Parallel G1 Evacuation HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size) { assert(!isHumongous(word_size), err_msg("we should not be seeing humongous allocation requests " "during GC, word_size = "SIZE_FORMAT, word_size)); HeapRegion* alloc_region = _gc_alloc_regions[purpose]; // let the caller handle alloc failure if (alloc_region == NULL) return NULL; HeapWord* block = alloc_region->par_allocate(word_size); if (block == NULL) { block = allocate_during_gc_slow(purpose, alloc_region, true, word_size); } return block; } void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region, bool par) { // Another thread might have obtained alloc_region for the given // purpose, and might be attempting to allocate in it, and might // succeed. Therefore, we can't do the "finalization" stuff on the // region below until we're sure the last allocation has happened. // We ensure this by allocating the remaining space with a garbage // object. if (par) par_allocate_remaining_space(alloc_region); // Now we can do the post-GC stuff on the region. alloc_region->note_end_of_copying(); g1_policy()->record_after_bytes(alloc_region->used()); } HeapWord* G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose, HeapRegion* alloc_region, bool par, size_t word_size) { assert(!isHumongous(word_size), err_msg("we should not be seeing humongous allocation requests " "during GC, word_size = "SIZE_FORMAT, word_size)); // We need to make sure we serialize calls to this method. Given // that the FreeList_lock guards accesses to the free_list anyway, // and we need to potentially remove a region from it, we'll use it // to protect the whole call. MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); HeapWord* block = NULL; // In the parallel case, a previous thread to obtain the lock may have // already assigned a new gc_alloc_region. if (alloc_region != _gc_alloc_regions[purpose]) { assert(par, "But should only happen in parallel case."); alloc_region = _gc_alloc_regions[purpose]; if (alloc_region == NULL) return NULL; block = alloc_region->par_allocate(word_size); if (block != NULL) return block; // Otherwise, continue; this new region is empty, too. } assert(alloc_region != NULL, "We better have an allocation region"); retire_alloc_region(alloc_region, par); if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) { // Cannot allocate more regions for the given purpose. GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose); // Is there an alternative? if (purpose != alt_purpose) { HeapRegion* alt_region = _gc_alloc_regions[alt_purpose]; // Has not the alternative region been aliased? if (alloc_region != alt_region && alt_region != NULL) { // Try to allocate in the alternative region. if (par) { block = alt_region->par_allocate(word_size); } else { block = alt_region->allocate(word_size); } // Make an alias. _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose]; if (block != NULL) { return block; } retire_alloc_region(alt_region, par); } // Both the allocation region and the alternative one are full // and aliased, replace them with a new allocation region. purpose = alt_purpose; } else { set_gc_alloc_region(purpose, NULL); return NULL; } } // Now allocate a new region for allocation. alloc_region = new_gc_alloc_region(purpose, word_size); // let the caller handle alloc failure if (alloc_region != NULL) { assert(check_gc_alloc_regions(), "alloc regions messed up"); assert(alloc_region->saved_mark_at_top(), "Mark should have been saved already."); // This must be done last: once it's installed, other regions may // allocate in it (without holding the lock.) set_gc_alloc_region(purpose, alloc_region); if (par) { block = alloc_region->par_allocate(word_size); } else { block = alloc_region->allocate(word_size); } // Caller handles alloc failure. } else { // This sets other apis using the same old alloc region to NULL, also. set_gc_alloc_region(purpose, NULL); } return block; // May be NULL. } void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) { HeapWord* block = NULL; size_t free_words; do { free_words = r->free()/HeapWordSize; // If there's too little space, no one can allocate, so we're done. if (free_words < CollectedHeap::min_fill_size()) return; // Otherwise, try to claim it. block = r->par_allocate(free_words); } while (block == NULL); fill_with_object(block, free_words); } #ifndef PRODUCT bool GCLabBitMapClosure::do_bit(size_t offset) { HeapWord* addr = _bitmap->offsetToHeapWord(offset); guarantee(_cm->isMarked(oop(addr)), "it should be!"); return true; } #endif // PRODUCT G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num) : _g1h(g1h), _refs(g1h->task_queue(queue_num)), _dcq(&g1h->dirty_card_queue_set()), _ct_bs((CardTableModRefBS*)_g1h->barrier_set()), _g1_rem(g1h->g1_rem_set()), _hash_seed(17), _queue_num(queue_num), _term_attempts(0), _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)), _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)), _age_table(false), _strong_roots_time(0), _term_time(0), _alloc_buffer_waste(0), _undo_waste(0) { // we allocate G1YoungSurvRateNumRegions plus one entries, since // we "sacrifice" entry 0 to keep track of surviving bytes for // non-young regions (where the age is -1) // We also add a few elements at the beginning and at the end in // an attempt to eliminate cache contention size_t real_length = 1 + _g1h->g1_policy()->young_cset_length(); size_t array_length = PADDING_ELEM_NUM + real_length + PADDING_ELEM_NUM; _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length); if (_surviving_young_words_base == NULL) vm_exit_out_of_memory(array_length * sizeof(size_t), "Not enough space for young surv histo."); _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; memset(_surviving_young_words, 0, real_length * sizeof(size_t)); _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer; _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer; _start = os::elapsedTime(); } void G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) { st->print_raw_cr("GC Termination Stats"); st->print_raw_cr(" elapsed --strong roots-- -------termination-------" " ------waste (KiB)------"); st->print_raw_cr("thr ms ms % ms % attempts" " total alloc undo"); st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" " ------- ------- -------"); } void G1ParScanThreadState::print_termination_stats(int i, outputStream* const st) const { const double elapsed_ms = elapsed_time() * 1000.0; const double s_roots_ms = strong_roots_time() * 1000.0; const double term_ms = term_time() * 1000.0; st->print_cr("%3d %9.2f %9.2f %6.2f " "%9.2f %6.2f " SIZE_FORMAT_W(8) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, term_ms, term_ms * 100 / elapsed_ms, term_attempts(), (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K, alloc_buffer_waste() * HeapWordSize / K, undo_waste() * HeapWordSize / K); } #ifdef ASSERT bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { assert(ref != NULL, "invariant"); assert(UseCompressedOops, "sanity"); assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref)); oop p = oopDesc::load_decode_heap_oop(ref); assert(_g1h->is_in_g1_reserved(p), err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); return true; } bool G1ParScanThreadState::verify_ref(oop* ref) const { assert(ref != NULL, "invariant"); if (has_partial_array_mask(ref)) { // Must be in the collection set--it's already been copied. oop p = clear_partial_array_mask(ref); assert(_g1h->obj_in_cs(p), err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); } else { oop p = oopDesc::load_decode_heap_oop(ref); assert(_g1h->is_in_g1_reserved(p), err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p))); } return true; } bool G1ParScanThreadState::verify_task(StarTask ref) const { if (ref.is_narrow()) { return verify_ref((narrowOop*) ref); } else { return verify_ref((oop*) ref); } } #endif // ASSERT void G1ParScanThreadState::trim_queue() { StarTask ref; do { // Drain the overflow stack first, so other threads can steal. while (refs()->pop_overflow(ref)) { deal_with_reference(ref); } while (refs()->pop_local(ref)) { deal_with_reference(ref); } } while (!refs()->is_empty()); } G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) : _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()), _par_scan_state(par_scan_state) { } template <class T> void G1ParCopyHelper::mark_forwardee(T* p) { // This is called _after_ do_oop_work has been called, hence after // the object has been relocated to its new location and *p points // to its new location. T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop obj = oopDesc::decode_heap_oop(heap_oop); assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)), "shouldn't still be in the CSet if evacuation didn't fail."); HeapWord* addr = (HeapWord*)obj; if (_g1->is_in_g1_reserved(addr)) _cm->grayRoot(oop(addr)); } } oop G1ParCopyHelper::copy_to_survivor_space(oop old) { size_t word_sz = old->size(); HeapRegion* from_region = _g1->heap_region_containing_raw(old); // +1 to make the -1 indexes valid... int young_index = from_region->young_index_in_cset()+1; assert( (from_region->is_young() && young_index > 0) || (!from_region->is_young() && young_index == 0), "invariant" ); G1CollectorPolicy* g1p = _g1->g1_policy(); markOop m = old->mark(); int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age() : m->age(); GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age, word_sz); HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz); oop obj = oop(obj_ptr); if (obj_ptr == NULL) { // This will either forward-to-self, or detect that someone else has // installed a forwarding pointer. OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); return _g1->handle_evacuation_failure_par(cl, old); } // We're going to allocate linearly, so might as well prefetch ahead. Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); oop forward_ptr = old->forward_to_atomic(obj); if (forward_ptr == NULL) { Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); if (g1p->track_object_age(alloc_purpose)) { // We could simply do obj->incr_age(). However, this causes a // performance issue. obj->incr_age() will first check whether // the object has a displaced mark by checking its mark word; // getting the mark word from the new location of the object // stalls. So, given that we already have the mark word and we // are about to install it anyway, it's better to increase the // age on the mark word, when the object does not have a // displaced mark word. We're not expecting many objects to have // a displaced marked word, so that case is not optimized // further (it could be...) and we simply call obj->incr_age(). if (m->has_displaced_mark_helper()) { // in this case, we have to install the mark word first, // otherwise obj looks to be forwarded (the old mark word, // which contains the forward pointer, was copied) obj->set_mark(m); obj->incr_age(); } else { m = m->incr_age(); obj->set_mark(m); } _par_scan_state->age_table()->add(obj, word_sz); } else { obj->set_mark(m); } // preserve "next" mark bit if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) { if (!use_local_bitmaps || !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) { // if we couldn't mark it on the local bitmap (this happens when // the object was not allocated in the GCLab), we have to bite // the bullet and do the standard parallel mark _cm->markAndGrayObjectIfNecessary(obj); } #if 1 if (_g1->isMarkedNext(old)) { _cm->nextMarkBitMap()->parClear((HeapWord*)old); } #endif } size_t* surv_young_words = _par_scan_state->surviving_young_words(); surv_young_words[young_index] += word_sz; if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { arrayOop(old)->set_length(0); oop* old_p = set_partial_array_mask(old); _par_scan_state->push_on_queue(old_p); } else { // No point in using the slower heap_region_containing() method, // given that we know obj is in the heap. _scanner->set_region(_g1->heap_region_containing_raw(obj)); obj->oop_iterate_backwards(_scanner); } } else { _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz); obj = forward_ptr; } return obj; } template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee> template <class T> void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee> ::do_oop_work(T* p) { oop obj = oopDesc::load_decode_heap_oop(p); assert(barrier != G1BarrierRS || obj != NULL, "Precondition: G1BarrierRS implies obj is nonNull"); // here the null check is implicit in the cset_fast_test() test if (_g1->in_cset_fast_test(obj)) { #if G1_REM_SET_LOGGING gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" " "into CS.", p, (void*) obj); #endif if (obj->is_forwarded()) { oopDesc::encode_store_heap_oop(p, obj->forwardee()); } else { oop copy_oop = copy_to_survivor_space(obj); oopDesc::encode_store_heap_oop(p, copy_oop); } // When scanning the RS, we only care about objs in CS. if (barrier == G1BarrierRS) { _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num()); } } if (barrier == G1BarrierEvac && obj != NULL) { _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num()); } if (do_gen_barrier && obj != NULL) { par_do_barrier(p); } } template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p); template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p); template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) { assert(has_partial_array_mask(p), "invariant"); oop old = clear_partial_array_mask(p); 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."); objArrayOop obj = objArrayOop(old->forwardee()); assert((void*)old != (void*)old->forwardee(), "self forwarding here?"); // 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. oop* old_p = set_partial_array_mask(old); assert(arrayOop(old)->length() < obj->length(), "Empty push?"); _par_scan_state->push_on_queue(old_p); } else { // Restore length so that the heap remains parsable in // case of evacuation failure. arrayOop(old)->set_length(end); } _scanner.set_region(_g1->heap_region_containing_raw(obj)); // process our set of indices (include header in first chunk) obj->oop_iterate_range(&_scanner, start, end); } class G1ParEvacuateFollowersClosure : public VoidClosure { protected: G1CollectedHeap* _g1h; G1ParScanThreadState* _par_scan_state; RefToScanQueueSet* _queues; ParallelTaskTerminator* _terminator; G1ParScanThreadState* par_scan_state() { return _par_scan_state; } RefToScanQueueSet* queues() { return _queues; } ParallelTaskTerminator* terminator() { return _terminator; } public: G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, G1ParScanThreadState* par_scan_state, RefToScanQueueSet* queues, ParallelTaskTerminator* terminator) : _g1h(g1h), _par_scan_state(par_scan_state), _queues(queues), _terminator(terminator) {} void do_void(); private: inline bool offer_termination(); }; bool G1ParEvacuateFollowersClosure::offer_termination() { G1ParScanThreadState* const pss = par_scan_state(); pss->start_term_time(); const bool res = terminator()->offer_termination(); pss->end_term_time(); return res; } void G1ParEvacuateFollowersClosure::do_void() { StarTask stolen_task; G1ParScanThreadState* const pss = par_scan_state(); pss->trim_queue(); do { while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) { assert(pss->verify_task(stolen_task), "sanity"); if (stolen_task.is_narrow()) { pss->deal_with_reference((narrowOop*) stolen_task); } else { pss->deal_with_reference((oop*) stolen_task); } // We've just processed a reference and we might have made // available new entries on the queues. So we have to make sure // we drain the queues as necessary. pss->trim_queue(); } } while (!offer_termination()); pss->retire_alloc_buffers(); } class G1ParTask : public AbstractGangTask { protected: G1CollectedHeap* _g1h; RefToScanQueueSet *_queues; ParallelTaskTerminator _terminator; int _n_workers; Mutex _stats_lock; Mutex* stats_lock() { return &_stats_lock; } size_t getNCards() { return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) / G1BlockOffsetSharedArray::N_bytes; } public: G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues) : AbstractGangTask("G1 collection"), _g1h(g1h), _queues(task_queues), _terminator(workers, _queues), _stats_lock(Mutex::leaf, "parallel G1 stats lock", true), _n_workers(workers) {} RefToScanQueueSet* queues() { return _queues; } RefToScanQueue *work_queue(int i) { return queues()->queue(i); } void work(int i) { if (i >= _n_workers) return; // no work needed this round double start_time_ms = os::elapsedTime() * 1000.0; _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms); ResourceMark rm; HandleMark hm; G1ParScanThreadState pss(_g1h, i); G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss); G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss); G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss); pss.set_evac_closure(&scan_evac_cl); pss.set_evac_failure_closure(&evac_failure_cl); pss.set_partial_scan_closure(&partial_scan_cl); G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss); G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss); G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss); G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss); G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss); G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss); OopsInHeapRegionClosure *scan_root_cl; OopsInHeapRegionClosure *scan_perm_cl; if (_g1h->g1_policy()->during_initial_mark_pause()) { scan_root_cl = &scan_mark_root_cl; scan_perm_cl = &scan_mark_perm_cl; } else { scan_root_cl = &only_scan_root_cl; scan_perm_cl = &only_scan_perm_cl; } pss.start_strong_roots(); _g1h->g1_process_strong_roots(/* not collecting perm */ false, SharedHeap::SO_AllClasses, scan_root_cl, &push_heap_rs_cl, scan_perm_cl, i); pss.end_strong_roots(); { double start = os::elapsedTime(); G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); evac.do_void(); double elapsed_ms = (os::elapsedTime()-start)*1000.0; double term_ms = pss.term_time()*1000.0; _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms); _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts()); } _g1h->g1_policy()->record_thread_age_table(pss.age_table()); _g1h->update_surviving_young_words(pss.surviving_young_words()+1); // Clean up any par-expanded rem sets. HeapRegionRemSet::par_cleanup(); if (ParallelGCVerbose) { MutexLocker x(stats_lock()); pss.print_termination_stats(i); } assert(pss.refs()->is_empty(), "should be empty"); double end_time_ms = os::elapsedTime() * 1000.0; _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms); } }; // *** Common G1 Evacuation Stuff // This method is run in a GC worker. void G1CollectedHeap:: g1_process_strong_roots(bool collecting_perm_gen, SharedHeap::ScanningOption so, OopClosure* scan_non_heap_roots, OopsInHeapRegionClosure* scan_rs, OopsInGenClosure* scan_perm, int worker_i) { // First scan the strong roots, including the perm gen. double ext_roots_start = os::elapsedTime(); double closure_app_time_sec = 0.0; BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots); BufferingOopsInGenClosure buf_scan_perm(scan_perm); buf_scan_perm.set_generation(perm_gen()); // Walk the code cache w/o buffering, because StarTask cannot handle // unaligned oop locations. CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true); process_strong_roots(false, // no scoping; this is parallel code collecting_perm_gen, so, &buf_scan_non_heap_roots, &eager_scan_code_roots, &buf_scan_perm); // Finish up any enqueued closure apps. buf_scan_non_heap_roots.done(); buf_scan_perm.done(); double ext_roots_end = os::elapsedTime(); g1_policy()->reset_obj_copy_time(worker_i); double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds() + buf_scan_perm.closure_app_seconds(); g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0); double ext_root_time_ms = ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0; g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms); // Scan strong roots in mark stack. if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) { concurrent_mark()->oops_do(scan_non_heap_roots); } double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0; g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms); // XXX What should this be doing in the parallel case? g1_policy()->record_collection_pause_end_CH_strong_roots(); // Now scan the complement of the collection set. if (scan_rs != NULL) { g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i); } // Finish with the ref_processor roots. if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) { // We need to treat the discovered reference lists as roots and // keep entries (which are added by the marking threads) on them // live until they can be processed at the end of marking. ref_processor()->weak_oops_do(scan_non_heap_roots); ref_processor()->oops_do(scan_non_heap_roots); } g1_policy()->record_collection_pause_end_G1_strong_roots(); _process_strong_tasks->all_tasks_completed(); } void G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure, OopClosure* non_root_closure) { CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false); SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure); } class SaveMarksClosure: public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* r) { r->save_marks(); return false; } }; void G1CollectedHeap::save_marks() { if (!CollectedHeap::use_parallel_gc_threads()) { SaveMarksClosure sm; heap_region_iterate(&sm); } // We do this even in the parallel case perm_gen()->save_marks(); } void G1CollectedHeap::evacuate_collection_set() { set_evacuation_failed(false); g1_rem_set()->prepare_for_oops_into_collection_set_do(); concurrent_g1_refine()->set_use_cache(false); concurrent_g1_refine()->clear_hot_cache_claimed_index(); int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1); set_par_threads(n_workers); G1ParTask g1_par_task(this, n_workers, _task_queues); init_for_evac_failure(NULL); rem_set()->prepare_for_younger_refs_iterate(true); assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); double start_par = os::elapsedTime(); if (G1CollectedHeap::use_parallel_gc_threads()) { // The individual threads will set their evac-failure closures. StrongRootsScope srs(this); if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr(); workers()->run_task(&g1_par_task); } else { StrongRootsScope srs(this); g1_par_task.work(0); } double par_time = (os::elapsedTime() - start_par) * 1000.0; g1_policy()->record_par_time(par_time); set_par_threads(0); // Is this the right thing to do here? We don't save marks // on individual heap regions when we allocate from // them in parallel, so this seems like the correct place for this. retire_all_alloc_regions(); // Weak root processing. // Note: when JSR 292 is enabled and code blobs can contain // non-perm oops then we will need to process the code blobs // here too. { G1IsAliveClosure is_alive(this); G1KeepAliveClosure keep_alive(this); JNIHandles::weak_oops_do(&is_alive, &keep_alive); } release_gc_alloc_regions(false /* totally */); g1_rem_set()->cleanup_after_oops_into_collection_set_do(); concurrent_g1_refine()->clear_hot_cache(); concurrent_g1_refine()->set_use_cache(true); finalize_for_evac_failure(); // Must do this before removing self-forwarding pointers, which clears // the per-region evac-failure flags. concurrent_mark()->complete_marking_in_collection_set(); if (evacuation_failed()) { remove_self_forwarding_pointers(); if (PrintGCDetails) { gclog_or_tty->print(" (to-space overflow)"); } else if (PrintGC) { gclog_or_tty->print("--"); } } if (G1DeferredRSUpdate) { RedirtyLoggedCardTableEntryFastClosure redirty; dirty_card_queue_set().set_closure(&redirty); dirty_card_queue_set().apply_closure_to_all_completed_buffers(); DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); dcq.merge_bufferlists(&dirty_card_queue_set()); assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); } COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); } void G1CollectedHeap::free_region_if_empty(HeapRegion* hr, size_t* pre_used, FreeRegionList* free_list, HumongousRegionSet* humongous_proxy_set, HRRSCleanupTask* hrrs_cleanup_task, bool par) { if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) { if (hr->isHumongous()) { assert(hr->startsHumongous(), "we should only see starts humongous"); free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par); } else { free_region(hr, pre_used, free_list, par); } } else { hr->rem_set()->do_cleanup_work(hrrs_cleanup_task); } } void G1CollectedHeap::free_region(HeapRegion* hr, size_t* pre_used, FreeRegionList* free_list, bool par) { assert(!hr->isHumongous(), "this is only for non-humongous regions"); assert(!hr->is_empty(), "the region should not be empty"); assert(free_list != NULL, "pre-condition"); *pre_used += hr->used(); hr->hr_clear(par, true /* clear_space */); free_list->add_as_tail(hr); } void G1CollectedHeap::free_humongous_region(HeapRegion* hr, size_t* pre_used, FreeRegionList* free_list, HumongousRegionSet* humongous_proxy_set, bool par) { assert(hr->startsHumongous(), "this is only for starts humongous regions"); assert(free_list != NULL, "pre-condition"); assert(humongous_proxy_set != NULL, "pre-condition"); size_t hr_used = hr->used(); size_t hr_capacity = hr->capacity(); size_t hr_pre_used = 0; _humongous_set.remove_with_proxy(hr, humongous_proxy_set); hr->set_notHumongous(); free_region(hr, &hr_pre_used, free_list, par); int i = hr->hrs_index() + 1; size_t num = 1; while ((size_t) i < n_regions()) { HeapRegion* curr_hr = _hrs->at(i); if (!curr_hr->continuesHumongous()) { break; } curr_hr->set_notHumongous(); free_region(curr_hr, &hr_pre_used, free_list, par); num += 1; i += 1; } assert(hr_pre_used == hr_used, err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" " "should be the same", hr_pre_used, hr_used)); *pre_used += hr_pre_used; } void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used, FreeRegionList* free_list, HumongousRegionSet* humongous_proxy_set, bool par) { if (pre_used > 0) { Mutex* lock = (par) ? ParGCRareEvent_lock : NULL; MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); assert(_summary_bytes_used >= pre_used, err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" " "should be >= pre_used: "SIZE_FORMAT, _summary_bytes_used, pre_used)); _summary_bytes_used -= pre_used; } if (free_list != NULL && !free_list->is_empty()) { MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); _free_list.add_as_tail(free_list); } if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) { MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); _humongous_set.update_from_proxy(humongous_proxy_set); } } void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) { while (list != NULL) { guarantee( list->is_young(), "invariant" ); HeapWord* bottom = list->bottom(); HeapWord* end = list->end(); MemRegion mr(bottom, end); ct_bs->dirty(mr); list = list->get_next_young_region(); } } class G1ParCleanupCTTask : public AbstractGangTask { CardTableModRefBS* _ct_bs; G1CollectedHeap* _g1h; HeapRegion* volatile _su_head; public: G1ParCleanupCTTask(CardTableModRefBS* ct_bs, G1CollectedHeap* g1h, HeapRegion* survivor_list) : AbstractGangTask("G1 Par Cleanup CT Task"), _ct_bs(ct_bs), _g1h(g1h), _su_head(survivor_list) { } void work(int i) { HeapRegion* r; while (r = _g1h->pop_dirty_cards_region()) { clear_cards(r); } // Redirty the cards of the survivor regions. dirty_list(&this->_su_head); } void clear_cards(HeapRegion* r) { // Cards for Survivor regions will be dirtied later. if (!r->is_survivor()) { _ct_bs->clear(MemRegion(r->bottom(), r->end())); } } void dirty_list(HeapRegion* volatile * head_ptr) { HeapRegion* head; do { // Pop region off the list. head = *head_ptr; if (head != NULL) { HeapRegion* r = (HeapRegion*) Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head); if (r == head) { assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list"); _ct_bs->dirty(MemRegion(r->bottom(), r->end())); } } } while (*head_ptr != NULL); } }; #ifndef PRODUCT class G1VerifyCardTableCleanup: public HeapRegionClosure { CardTableModRefBS* _ct_bs; public: G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs) : _ct_bs(ct_bs) { } virtual bool doHeapRegion(HeapRegion* r) { MemRegion mr(r->bottom(), r->end()); if (r->is_survivor()) { _ct_bs->verify_dirty_region(mr); } else { _ct_bs->verify_clean_region(mr); } return false; } }; #endif void G1CollectedHeap::cleanUpCardTable() { CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); double start = os::elapsedTime(); // Iterate over the dirty cards region list. G1ParCleanupCTTask cleanup_task(ct_bs, this, _young_list->first_survivor_region()); if (ParallelGCThreads > 0) { set_par_threads(workers()->total_workers()); workers()->run_task(&cleanup_task); set_par_threads(0); } else { while (_dirty_cards_region_list) { HeapRegion* r = _dirty_cards_region_list; cleanup_task.clear_cards(r); _dirty_cards_region_list = r->get_next_dirty_cards_region(); if (_dirty_cards_region_list == r) { // The last region. _dirty_cards_region_list = NULL; } r->set_next_dirty_cards_region(NULL); } // now, redirty the cards of the survivor regions // (it seemed faster to do it this way, instead of iterating over // all regions and then clearing / dirtying as appropriate) dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region()); } double elapsed = os::elapsedTime() - start; g1_policy()->record_clear_ct_time( elapsed * 1000.0); #ifndef PRODUCT if (G1VerifyCTCleanup || VerifyAfterGC) { G1VerifyCardTableCleanup cleanup_verifier(ct_bs); heap_region_iterate(&cleanup_verifier); } #endif } void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) { size_t pre_used = 0; FreeRegionList local_free_list("Local List for CSet Freeing"); double young_time_ms = 0.0; double non_young_time_ms = 0.0; // Since the collection set is a superset of the the young list, // all we need to do to clear the young list is clear its // head and length, and unlink any young regions in the code below _young_list->clear(); G1CollectorPolicy* policy = g1_policy(); double start_sec = os::elapsedTime(); bool non_young = true; HeapRegion* cur = cs_head; int age_bound = -1; size_t rs_lengths = 0; while (cur != NULL) { assert(!is_on_master_free_list(cur), "sanity"); if (non_young) { if (cur->is_young()) { double end_sec = os::elapsedTime(); double elapsed_ms = (end_sec - start_sec) * 1000.0; non_young_time_ms += elapsed_ms; start_sec = os::elapsedTime(); non_young = false; } } else { double end_sec = os::elapsedTime(); double elapsed_ms = (end_sec - start_sec) * 1000.0; young_time_ms += elapsed_ms; start_sec = os::elapsedTime(); non_young = true; } rs_lengths += cur->rem_set()->occupied(); HeapRegion* next = cur->next_in_collection_set(); assert(cur->in_collection_set(), "bad CS"); cur->set_next_in_collection_set(NULL); cur->set_in_collection_set(false); if (cur->is_young()) { int index = cur->young_index_in_cset(); guarantee( index != -1, "invariant" ); guarantee( (size_t)index < policy->young_cset_length(), "invariant" ); size_t words_survived = _surviving_young_words[index]; cur->record_surv_words_in_group(words_survived); // At this point the we have 'popped' cur from the collection set // (linked via next_in_collection_set()) but it is still in the // young list (linked via next_young_region()). Clear the // _next_young_region field. cur->set_next_young_region(NULL); } else { int index = cur->young_index_in_cset(); guarantee( index == -1, "invariant" ); } assert( (cur->is_young() && cur->young_index_in_cset() > -1) || (!cur->is_young() && cur->young_index_in_cset() == -1), "invariant" ); if (!cur->evacuation_failed()) { // And the region is empty. assert(!cur->is_empty(), "Should not have empty regions in a CS."); free_region(cur, &pre_used, &local_free_list, false /* par */); } else { cur->uninstall_surv_rate_group(); if (cur->is_young()) cur->set_young_index_in_cset(-1); cur->set_not_young(); cur->set_evacuation_failed(false); } cur = next; } policy->record_max_rs_lengths(rs_lengths); policy->cset_regions_freed(); double end_sec = os::elapsedTime(); double elapsed_ms = (end_sec - start_sec) * 1000.0; if (non_young) non_young_time_ms += elapsed_ms; else young_time_ms += elapsed_ms; update_sets_after_freeing_regions(pre_used, &local_free_list, NULL /* humongous_proxy_set */, false /* par */); policy->record_young_free_cset_time_ms(young_time_ms); policy->record_non_young_free_cset_time_ms(non_young_time_ms); } // This routine is similar to the above but does not record // any policy statistics or update free lists; we are abandoning // the current incremental collection set in preparation of a // full collection. After the full GC we will start to build up // the incremental collection set again. // This is only called when we're doing a full collection // and is immediately followed by the tearing down of the young list. void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { HeapRegion* cur = cs_head; while (cur != NULL) { HeapRegion* next = cur->next_in_collection_set(); assert(cur->in_collection_set(), "bad CS"); cur->set_next_in_collection_set(NULL); cur->set_in_collection_set(false); cur->set_young_index_in_cset(-1); cur = next; } } void G1CollectedHeap::set_free_regions_coming() { if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " "setting free regions coming"); } assert(!free_regions_coming(), "pre-condition"); _free_regions_coming = true; } void G1CollectedHeap::reset_free_regions_coming() { { assert(free_regions_coming(), "pre-condition"); MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); _free_regions_coming = false; SecondaryFreeList_lock->notify_all(); } if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " "reset free regions coming"); } } void G1CollectedHeap::wait_while_free_regions_coming() { // Most of the time we won't have to wait, so let's do a quick test // first before we take the lock. if (!free_regions_coming()) { return; } if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " "waiting for free regions"); } { MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); while (free_regions_coming()) { SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); } } if (G1ConcRegionFreeingVerbose) { gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " "done waiting for free regions"); } } size_t G1CollectedHeap::n_regions() { return _hrs->length(); } size_t G1CollectedHeap::max_regions() { return (size_t)align_size_up(max_capacity(), HeapRegion::GrainBytes) / HeapRegion::GrainBytes; } void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { assert(heap_lock_held_for_gc(), "the heap lock should already be held by or for this thread"); _young_list->push_region(hr); g1_policy()->set_region_short_lived(hr); } class NoYoungRegionsClosure: public HeapRegionClosure { private: bool _success; public: NoYoungRegionsClosure() : _success(true) { } bool doHeapRegion(HeapRegion* r) { if (r->is_young()) { gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", r->bottom(), r->end()); _success = false; } return false; } bool success() { return _success; } }; bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { bool ret = _young_list->check_list_empty(check_sample); if (check_heap) { NoYoungRegionsClosure closure; heap_region_iterate(&closure); ret = ret && closure.success(); } return ret; } void G1CollectedHeap::empty_young_list() { assert(heap_lock_held_for_gc(), "the heap lock should already be held by or for this thread"); assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode"); _young_list->empty_list(); } bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() { bool no_allocs = true; for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) { HeapRegion* r = _gc_alloc_regions[ap]; no_allocs = r == NULL || r->saved_mark_at_top(); } return no_allocs; } void G1CollectedHeap::retire_all_alloc_regions() { for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { HeapRegion* r = _gc_alloc_regions[ap]; if (r != NULL) { // Check for aliases. bool has_processed_alias = false; for (int i = 0; i < ap; ++i) { if (_gc_alloc_regions[i] == r) { has_processed_alias = true; break; } } if (!has_processed_alias) { retire_alloc_region(r, false /* par */); } } } } // Done at the start of full GC. void G1CollectedHeap::tear_down_region_lists() { _free_list.remove_all(); } class RegionResetter: public HeapRegionClosure { G1CollectedHeap* _g1h; FreeRegionList _local_free_list; public: RegionResetter() : _g1h(G1CollectedHeap::heap()), _local_free_list("Local Free List for RegionResetter") { } bool doHeapRegion(HeapRegion* r) { if (r->continuesHumongous()) return false; if (r->top() > r->bottom()) { if (r->top() < r->end()) { Copy::fill_to_words(r->top(), pointer_delta(r->end(), r->top())); } } else { assert(r->is_empty(), "tautology"); _local_free_list.add_as_tail(r); } return false; } void update_free_lists() { _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL, false /* par */); } }; // Done at the end of full GC. void G1CollectedHeap::rebuild_region_lists() { // This needs to go at the end of the full GC. RegionResetter rs; heap_region_iterate(&rs); rs.update_free_lists(); } void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { _refine_cte_cl->set_concurrent(concurrent); } bool G1CollectedHeap::is_in_closed_subset(const void* p) const { HeapRegion* hr = heap_region_containing(p); if (hr == NULL) { return is_in_permanent(p); } else { return hr->is_in(p); } } class VerifyRegionListsClosure : public HeapRegionClosure { private: HumongousRegionSet* _humongous_set; FreeRegionList* _free_list; size_t _region_count; public: VerifyRegionListsClosure(HumongousRegionSet* humongous_set, FreeRegionList* free_list) : _humongous_set(humongous_set), _free_list(free_list), _region_count(0) { } size_t region_count() { return _region_count; } bool doHeapRegion(HeapRegion* hr) { _region_count += 1; if (hr->continuesHumongous()) { return false; } if (hr->is_young()) { // TODO } else if (hr->startsHumongous()) { _humongous_set->verify_next_region(hr); } else if (hr->is_empty()) { _free_list->verify_next_region(hr); } return false; } }; void G1CollectedHeap::verify_region_sets() { assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); // First, check the explicit lists. _free_list.verify(); { // Given that a concurrent operation might be adding regions to // the secondary free list we have to take the lock before // verifying it. MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); _secondary_free_list.verify(); } _humongous_set.verify(); // If a concurrent region freeing operation is in progress it will // be difficult to correctly attributed any free regions we come // across to the correct free list given that they might belong to // one of several (free_list, secondary_free_list, any local lists, // etc.). So, if that's the case we will skip the rest of the // verification operation. Alternatively, waiting for the concurrent // operation to complete will have a non-trivial effect on the GC's // operation (no concurrent operation will last longer than the // interval between two calls to verification) and it might hide // any issues that we would like to catch during testing. if (free_regions_coming()) { return; } // Make sure we append the secondary_free_list on the free_list so // that all free regions we will come across can be safely // attributed to the free_list. append_secondary_free_list_if_not_empty_with_lock(); // Finally, make sure that the region accounting in the lists is // consistent with what we see in the heap. _humongous_set.verify_start(); _free_list.verify_start(); VerifyRegionListsClosure cl(&_humongous_set, &_free_list); heap_region_iterate(&cl); _humongous_set.verify_end(); _free_list.verify_end(); }