Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @ 647:bd441136a5ce
Merge
author | kvn |
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date | Thu, 19 Mar 2009 09:13:24 -0700 |
parents | ba50942c8138 660978a2a31a |
children | 96b229c54d1e |
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/* * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ #include "incls/_precompiled.incl" #include "incls/_g1CollectedHeap.cpp.incl" // 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 SCAN_ONLY_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_work, which all such allocation functions call. // (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. // Finds the first HeapRegion. // No longer used, but might be handy someday. class FindFirstRegionClosure: public HeapRegionClosure { HeapRegion* _a_region; public: FindFirstRegionClosure() : _a_region(NULL) {} bool doHeapRegion(HeapRegion* r) { _a_region = r; return true; } HeapRegion* result() { return _a_region; } }; 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) { _g1rs->concurrentRefineOneCard(card_ptr, worker_i); 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), _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL), _length(0), _scan_only_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; } HeapRegion* YoungList::pop_region() { while (_head != NULL) { assert( length() > 0, "list should not be empty" ); HeapRegion* ret = _head; _head = ret->get_next_young_region(); ret->set_next_young_region(NULL); --_length; assert(ret->is_young(), "region should be very young"); // Replace 'Survivor' region type with 'Young'. So the region will // be treated as a young region and will not be 'confused' with // newly created survivor regions. if (ret->is_survivor()) { ret->set_young(); } if (!ret->is_scan_only()) { return ret; } // scan-only, we'll add it to the scan-only list if (_scan_only_tail == NULL) { guarantee( _scan_only_head == NULL, "invariant" ); _scan_only_head = ret; _curr_scan_only = ret; } else { guarantee( _scan_only_head != NULL, "invariant" ); _scan_only_tail->set_next_young_region(ret); } guarantee( ret->get_next_young_region() == NULL, "invariant" ); _scan_only_tail = ret; // no need to be tagged as scan-only any more ret->set_young(); ++_scan_only_length; } assert( length() == 0, "list should be empty" ); return NULL; } 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(_scan_only_head); _scan_only_head = NULL; _scan_only_tail = NULL; _scan_only_length = 0; _curr_scan_only = NULL; 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() || curr->is_scan_only()) { gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " "incorrectly tagged (%d, %d)", curr->bottom(), curr->end(), curr->is_young(), curr->is_scan_only()); 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); } bool scan_only_ret = true; length = 0; curr = _scan_only_head; last = NULL; while (curr != NULL) { if (!curr->is_young() || curr->is_scan_only()) { gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" " "incorrectly tagged (%d, %d)", curr->bottom(), curr->end(), curr->is_young(), curr->is_scan_only()); scan_only_ret = false; } ++length; last = curr; curr = curr->get_next_young_region(); } scan_only_ret = scan_only_ret && (length == _scan_only_length); if ( (last != _scan_only_tail) || (_scan_only_head == NULL && _scan_only_tail != NULL) || (_scan_only_head != NULL && _scan_only_tail == NULL) ) { gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly"); scan_only_ret = false; } if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) { gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly"); scan_only_ret = false; } if (!scan_only_ret) { gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!"); gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d", length, _scan_only_length); } return ret && scan_only_ret; } bool YoungList::check_list_empty(bool ignore_scan_only_list, 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"); } if (ignore_scan_only_list) return ret; bool scan_only_ret = true; if (_scan_only_length != 0) { gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d", _scan_only_length); scan_only_ret = false; } if (_scan_only_head != NULL) { gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head"); scan_only_ret = false; } if (_scan_only_tail != NULL) { gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail"); scan_only_ret = false; } if (!scan_only_ret) { gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty"); } return ret && scan_only_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" ); _sampled_rs_lengths += _curr->rem_set()->occupied(); _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() { // We could have just "moved" the scan-only list to the young list. // However, the scan-only list is ordered according to the region // age in descending order, so, by moving one entry at a time, we // ensure that it is recreated in ascending order. 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); } _g1h->g1_policy()->note_stop_adding_survivor_regions(); if (_survivor_head != NULL) { _head = _survivor_head; _length = _survivor_length + _scan_only_length; _survivor_tail->set_next_young_region(_scan_only_head); } else { _head = _scan_only_head; _length = _scan_only_length; } for (HeapRegion* curr = _scan_only_head; curr != NULL; curr = curr->get_next_young_region()) { curr->recalculate_age_in_surv_rate_group(); } _scan_only_head = NULL; _scan_only_tail = NULL; _scan_only_length = 0; _curr_scan_only = NULL; _survivor_head = NULL; _survivor_tail = NULL; _survivor_length = 0; _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, _scan_only_head, _survivor_head}; const char* names[] = {"YOUNG", "SCAN-ONLY", "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, s-o: %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_scan_only(), curr->is_survivor()); curr = curr->get_next_young_region(); } } gclog_or_tty->print_cr(""); } void G1CollectedHeap::stop_conc_gc_threads() { _cg1r->cg1rThread()->stop(); _czft->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. // Finds a HeapRegion that can be used to allocate a given size of block. HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size, bool do_expand, bool zero_filled) { ConcurrentZFThread::note_region_alloc(); HeapRegion* res = alloc_free_region_from_lists(zero_filled); if (res == NULL && do_expand) { expand(word_size * HeapWordSize); res = alloc_free_region_from_lists(zero_filled); assert(res == NULL || (!res->isHumongous() && (!zero_filled || res->zero_fill_state() == HeapRegion::Allocated)), "Alloc Regions must be zero filled (and non-H)"); } if (res != NULL && res->is_empty()) _free_regions--; assert(res == NULL || (!res->isHumongous() && (!zero_filled || res->zero_fill_state() == HeapRegion::Allocated)), "Non-young alloc Regions must be zero filled (and non-H)"); if (G1TraceRegions) { if (res != NULL) { 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::newAllocRegionWithExpansion(int purpose, size_t word_size, bool zero_filled) { HeapRegion* alloc_region = NULL; if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) { alloc_region = newAllocRegion_work(word_size, true, zero_filled); 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; } // 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::humongousObjAllocate(size_t word_size) { assert(regions_accounted_for(), "Region leakage!"); // We can't allocate H regions while cleanupComplete is running, since // some of the regions we find to be empty might not yet be added to the // unclean list. (If we're already at a safepoint, this call is // unnecessary, not to mention wrong.) if (!SafepointSynchronize::is_at_safepoint()) wait_for_cleanup_complete(); size_t num_regions = round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; // Special case if < one region??? // Remember the ft size. size_t x_size = expansion_regions(); HeapWord* res = NULL; bool eliminated_allocated_from_lists = false; // Can the allocation potentially fit in the free regions? if (free_regions() >= num_regions) { res = _hrs->obj_allocate(word_size); } if (res == NULL) { // Try expansion. size_t fs = _hrs->free_suffix(); if (fs + x_size >= num_regions) { expand((num_regions - fs) * HeapRegion::GrainBytes); res = _hrs->obj_allocate(word_size); assert(res != NULL, "This should have worked."); } else { // Expansion won't help. Are there enough free regions if we get rid // of reservations? size_t avail = free_regions(); if (avail >= num_regions) { res = _hrs->obj_allocate(word_size); if (res != NULL) { remove_allocated_regions_from_lists(); eliminated_allocated_from_lists = true; } } } } if (res != NULL) { // Increment by the number of regions allocated. // FIXME: Assumes regions all of size GrainBytes. #ifndef PRODUCT mr_bs()->verify_clean_region(MemRegion(res, res + num_regions * HeapRegion::GrainWords)); #endif if (!eliminated_allocated_from_lists) remove_allocated_regions_from_lists(); _summary_bytes_used += word_size * HeapWordSize; _free_regions -= num_regions; _num_humongous_regions += (int) num_regions; } assert(regions_accounted_for(), "Region Leakage"); return res; } HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, bool permit_collection_pause) { HeapWord* res = NULL; HeapRegion* allocated_young_region = NULL; assert( SafepointSynchronize::is_at_safepoint() || Heap_lock->owned_by_self(), "pre condition of the call" ); if (isHumongous(word_size)) { // Allocation of a humongous object can, in a sense, complete a // partial region, if the previous alloc was also humongous, and // caused the test below to succeed. if (permit_collection_pause) do_collection_pause_if_appropriate(word_size); res = humongousObjAllocate(word_size); assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(), "Prevent a regression of this bug."); } else { // We may have concurrent cleanup working at the time. Wait for it // to complete. In the future we would probably want to make the // concurrent cleanup truly concurrent by decoupling it from the // allocation. if (!SafepointSynchronize::is_at_safepoint()) wait_for_cleanup_complete(); // If we do a collection pause, this will be reset to a non-NULL // value. If we don't, nulling here ensures that we allocate a new // region below. if (_cur_alloc_region != NULL) { // We're finished with the _cur_alloc_region. _summary_bytes_used += _cur_alloc_region->used(); _cur_alloc_region = NULL; } assert(_cur_alloc_region == NULL, "Invariant."); // Completion of a heap region is perhaps a good point at which to do // a collection pause. if (permit_collection_pause) do_collection_pause_if_appropriate(word_size); // Make sure we have an allocation region available. if (_cur_alloc_region == NULL) { if (!SafepointSynchronize::is_at_safepoint()) wait_for_cleanup_complete(); bool next_is_young = should_set_young_locked(); // If the next region is not young, make sure it's zero-filled. _cur_alloc_region = newAllocRegion(word_size, !next_is_young); if (_cur_alloc_region != NULL) { _summary_bytes_used -= _cur_alloc_region->used(); if (next_is_young) { set_region_short_lived_locked(_cur_alloc_region); allocated_young_region = _cur_alloc_region; } } } assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(), "Prevent a regression of this bug."); // Now retry the allocation. if (_cur_alloc_region != NULL) { res = _cur_alloc_region->allocate(word_size); } } // NOTE: fails frequently in PRT assert(regions_accounted_for(), "Region leakage!"); if (res != NULL) { if (!SafepointSynchronize::is_at_safepoint()) { assert( permit_collection_pause, "invariant" ); assert( Heap_lock->owned_by_self(), "invariant" ); Heap_lock->unlock(); } if (allocated_young_region != NULL) { HeapRegion* hr = allocated_young_region; HeapWord* bottom = hr->bottom(); HeapWord* end = hr->end(); MemRegion mr(bottom, end); ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr); } } assert( SafepointSynchronize::is_at_safepoint() || (res == NULL && Heap_lock->owned_by_self()) || (res != NULL && !Heap_lock->owned_by_self()), "post condition of the call" ); return res; } HeapWord* G1CollectedHeap::mem_allocate(size_t word_size, bool is_noref, bool is_tlab, bool* gc_overhead_limit_was_exceeded) { debug_only(check_for_valid_allocation_state()); assert(no_gc_in_progress(), "Allocation during gc not allowed"); HeapWord* result = NULL; // Loop until the allocation is satisified, // or unsatisfied after GC. for (int try_count = 1; /* return or throw */; try_count += 1) { int gc_count_before; { Heap_lock->lock(); result = attempt_allocation(word_size); if (result != NULL) { // attempt_allocation should have unlocked the heap lock assert(is_in(result), "result not in heap"); return result; } // Read the gc count while the heap lock is held. gc_count_before = SharedHeap::heap()->total_collections(); Heap_lock->unlock(); } // Create the garbage collection operation... VM_G1CollectForAllocation op(word_size, gc_count_before); // ...and get the VM thread to execute it. VMThread::execute(&op); if (op.prologue_succeeded()) { result = op.result(); assert(result == NULL || is_in(result), "result not in heap"); return result; } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { warning("G1CollectedHeap::mem_allocate_work retries %d times", try_count); } } } void G1CollectedHeap::abandon_cur_alloc_region() { if (_cur_alloc_region != NULL) { // We're finished with the _cur_alloc_region. if (_cur_alloc_region->is_empty()) { _free_regions++; free_region(_cur_alloc_region); } else { _summary_bytes_used += _cur_alloc_region->used(); } _cur_alloc_region = NULL; } } 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()->as_HRInto_G1RemSet(), 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); } }; void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs, size_t word_size) { ResourceMark rm; if (full && DisableExplicitGC) { gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n"); return; } assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread"); if (GC_locker::is_active()) { return; // GC is disabled (e.g. JNI GetXXXCritical operation) } { IsGCActiveMark x; // Timing gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty); double start = os::elapsedTime(); GCOverheadReporter::recordSTWStart(start); g1_policy()->record_full_collection_start(); gc_prologue(true); increment_total_collections(); 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); } assert(regions_accounted_for(), "Region leakage!"); 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()->as_HRInto_G1RemSet()->cleanupHRRS(); tear_down_region_lists(); set_used_regions_to_need_zero_fill(); if (g1_policy()->in_young_gc_mode()) { empty_young_list(); g1_policy()->set_full_young_gcs(true); } // Temporarily make reference _discovery_ single threaded (non-MT). ReferenceProcessorMTMutator 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(clear_all_soft_refs); // Do collection work { HandleMark hm; // Discard invalid handles created during gc G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs); } // Because freeing humongous regions may have added some unclean // regions, it is necessary to tear down again before rebuilding. tear_down_region_lists(); rebuild_region_lists(); _summary_bytes_used = recalculate_used(); ref_processor()->enqueue_discovered_references(); COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 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(full ? 0 : word_size); if (_cg1r->use_cache()) { _cg1r->clear_and_record_card_counts(); _cg1r->clear_hot_cache(); } // Rebuild remembered sets of all regions. if (ParallelGCThreads > 0) { 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(); } double end = os::elapsedTime(); GCOverheadReporter::recordSTWEnd(end); g1_policy()->record_full_collection_end(); #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif gc_epilogue(true); // Abandon concurrent refinement. This must happen last: in the // dirty-card logging system, some cards may be dirty by weak-ref // processing, and may be enqueued. But the whole card table is // dirtied, so this should abandon those logs, and set "do_traversal" // to true. concurrent_g1_refine()->set_pya_restart(); assert(!G1DeferredRSUpdate || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any"); assert(regions_accounted_for(), "Region leakage!"); } if (g1_policy()->in_young_gc_mode()) { _young_list->reset_sampled_info(); assert( check_young_list_empty(false, false), "young list should be empty at this point"); } } void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { do_collection(true, clear_all_soft_refs, 0); } // 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; // We don't have floating point command-line arguments const double minimum_free_percentage = (double) MinHeapFreeRatio / 100; const double maximum_used_percentage = 1.0 - minimum_free_percentage; const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; const double minimum_used_percentage = 1.0 - maximum_free_percentage; size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage); size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage); // Don't shrink less than the initial size. minimum_desired_capacity = MAX2(minimum_desired_capacity, collector_policy()->initial_heap_byte_size()); maximum_desired_capacity = MAX2(maximum_desired_capacity, collector_policy()->initial_heap_byte_size()); // We are failing here because minimum_desired_capacity is assert(used_after_gc <= minimum_desired_capacity, "sanity check"); assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check"); if (PrintGC && Verbose) { const double free_percentage = ((double)free_after_gc) / capacity(); 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", capacity() / (double) K, minimum_desired_capacity / (double) K, maximum_desired_capacity / (double) K); gclog_or_tty->print_cr(" " " free_after_gc : %6.1fK" " used_after_gc : %6.1fK", free_after_gc / (double) K, used_after_gc / (double) K); gclog_or_tty->print_cr(" " " free_percentage: %6.2f", free_percentage); } if (capacity() < minimum_desired_capacity) { // Don't expand unless it's significant size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; expand(expand_bytes); if (PrintGC && Verbose) { gclog_or_tty->print_cr(" expanding:" " minimum_desired_capacity: %6.1fK" " expand_bytes: %6.1fK", minimum_desired_capacity / (double) K, expand_bytes / (double) K); } // No expansion, now see if we want to shrink } else if (capacity() > 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:" " initSize: %.1fK" " maximum_desired_capacity: %.1fK", collector_policy()->initial_heap_byte_size() / (double) K, maximum_desired_capacity / (double) K); gclog_or_tty->print_cr(" " " shrink_bytes: %.1fK", shrink_bytes / (double) K); } } } HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size) { HeapWord* result = NULL; // 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(is_in(result), "result not in heap"); return result; } // OK, I guess we have to try collection. do_collection(false, false, word_size); result = attempt_allocation(word_size, /*permit_collection_pause*/false); if (result != NULL) { assert(is_in(result), "result not in heap"); return result; } // Try collecting soft references. do_collection(false, true, word_size); result = attempt_allocation(word_size, /*permit_collection_pause*/false); if (result != NULL) { assert(is_in(result), "result not in heap"); return result; } // 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. 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) { size_t expand_bytes = word_size * HeapWordSize; if (expand_bytes < MinHeapDeltaBytes) { expand_bytes = MinHeapDeltaBytes; } expand(expand_bytes); assert(regions_accounted_for(), "Region leakage!"); HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */); return result; } size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) { size_t pre_used = 0; size_t cleared_h_regions = 0; size_t freed_regions = 0; UncleanRegionList local_list; free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions, freed_regions, &local_list); finish_free_region_work(pre_used, cleared_h_regions, freed_regions, &local_list); return pre_used; } void G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr, size_t& pre_used, size_t& cleared_h, size_t& freed_regions, UncleanRegionList* list, bool par) { assert(!hr->continuesHumongous(), "should have filtered these out"); size_t res = 0; if (!hr->popular() && hr->used() > 0 && hr->garbage_bytes() == hr->used()) { if (!hr->is_young()) { if (G1PolicyVerbose > 0) gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)" " during cleanup", hr, hr->used()); free_region_work(hr, pre_used, cleared_h, freed_regions, list, par); } } } // FIXME: both this and shrink could probably be more efficient by // doing one "VirtualSpace::expand_by" call rather than several. void G1CollectedHeap::expand(size_t expand_bytes) { size_t old_mem_size = _g1_storage.committed_size(); // We expand by a minimum of 1K. expand_bytes = MAX2(expand_bytes, (size_t)K); size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); aligned_expand_bytes = align_size_up(aligned_expand_bytes, HeapRegion::GrainBytes); expand_bytes = aligned_expand_bytes; while (expand_bytes > 0) { HeapWord* base = (HeapWord*)_g1_storage.high(); // Commit more storage. bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes); if (!successful) { expand_bytes = 0; } else { expand_bytes -= HeapRegion::GrainBytes; // Expand the committed region. HeapWord* high = (HeapWord*) _g1_storage.high(); _g1_committed.set_end(high); // 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); // Now update max_committed if necessary. _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high)); // Add it to the HeapRegionSeq. _hrs->insert(hr); // Set the zero-fill state, according to whether it's already // zeroed. { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); if (is_zeroed) { hr->set_zero_fill_complete(); put_free_region_on_list_locked(hr); } else { hr->set_zero_fill_needed(); put_region_on_unclean_list_locked(hr); } } _free_regions++; // And we used up an expansion region to create it. _expansion_regions--; // 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()); } } if (Verbose && PrintGC) { size_t new_mem_size = _g1_storage.committed_size(); gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK", old_mem_size/K, aligned_expand_bytes/K, new_mem_size/K); } } 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()); _free_regions -= num_regions_deleted; _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) { release_gc_alloc_regions(true /* totally */); tear_down_region_lists(); // We will rebuild them in a moment. shrink_helper(shrink_bytes); rebuild_region_lists(); } // 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_), _ref_processor(NULL), _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)), _bot_shared(NULL), _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"), _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL), _evac_failure_scan_stack(NULL) , _mark_in_progress(false), _cg1r(NULL), _czft(NULL), _summary_bytes_used(0), _cur_alloc_region(NULL), _refine_cte_cl(NULL), _free_region_list(NULL), _free_region_list_size(0), _free_regions(0), _popular_object_boundary(NULL), _cur_pop_hr_index(0), _popular_regions_to_be_evacuated(NULL), _pop_obj_rc_at_copy(), _full_collection(false), _unclean_region_list(), _unclean_regions_coming(false), _young_list(new YoungList(this)), _gc_time_stamp(0), _surviving_young_words(NULL), _in_cset_fast_test(NULL), _in_cset_fast_test_base(NULL) { _g1h = this; // To catch bugs. if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) { vm_exit_during_initialization("Failed necessary allocation."); } 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() { 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"); // We allocate this in any case, but only do no work if the command line // param is off. _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, false /*ism*/, 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, false /*ism*/, 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, false /*ism*/, 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; _num_humongous_regions = 0; // 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 (G1UseHRIntoRS) { if (mr_bs()->is_a(BarrierSet::CardTableModRef)) { _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs()); } else { vm_exit_during_initialization("G1 requires a cardtable mod ref bs."); return JNI_ENOMEM; } } else { _g1_rem_set = new StupidG1RemSet(this); } // 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"); _bot_shared = new G1BlockOffsetSharedArray(_reserved, heap_word_size(init_byte_size)); _g1h = this; // 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(); // ...and the concurrent zero-fill thread, if necessary. if (G1ConcZeroFill) { _czft = new ConcurrentZFThread(); } // Allocate the popular regions; take them off free lists. size_t pop_byte_size = G1NumPopularRegions * HeapRegion::GrainBytes; expand(pop_byte_size); _popular_object_boundary = _g1_reserved.start() + (G1NumPopularRegions * HeapRegion::GrainWords); for (int i = 0; i < G1NumPopularRegions; i++) { HeapRegion* hr = newAllocRegion(HeapRegion::GrainWords); // assert(hr != NULL && hr->bottom() < _popular_object_boundary, // "Should be enough, and all should be below boundary."); hr->set_popular(true); } assert(_cur_pop_hr_index == 0, "Start allocating at the first region."); // Initialize the from_card cache structure of HeapRegionRemSet. HeapRegionRemSet::init_heap(max_regions()); // Now expand into the rest of the initial heap size. expand(init_byte_size - pop_byte_size); // 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, 0, Shared_SATB_Q_lock); if (G1RSBarrierUseQueue) { JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, DirtyCardQ_FL_lock, G1DirtyCardQueueMax, Shared_DirtyCardQ_lock); } if (G1DeferredRSUpdate) { dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, DirtyCardQ_FL_lock, 0, 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(); const char* group_names[] = { "CR", "ZF", "CM", "CL" }; GCOverheadReporter::initGCOverheadReporter(4, group_names); return JNI_OK; } void G1CollectedHeap::ref_processing_init() { SharedHeap::ref_processing_init(); MemRegion mr = reserved_region(); _ref_processor = ReferenceProcessor::create_ref_processor( mr, // span false, // Reference discovery is not atomic // (though it shouldn't matter here.) true, // mt_discovery NULL, // is alive closure: need to fill this in for efficiency ParallelGCThreads, ParallelRefProcEnabled, 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(bool concurrent, int worker_i) { DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); int n_completed_buffers = 0; while (dcqs.apply_closure_to_completed_buffer(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(); // Finish up the queue... if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set()); 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; if (_cur_alloc_region != NULL) result += _cur_alloc_region->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: // _num is set to 1 to account for the popular region SumUsedRegionsClosure() : _num(G1NumPopularRegions) {} 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(); } 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"); MutexLocker ml(Heap_lock); collect_locked(cause); } void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { assert(Thread::current()->is_VM_thread(), "Precondition#1"); assert(Heap_lock->is_locked(), "Precondition#2"); 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_locked(GCCause::Cause cause) { // Don't want to do a GC until cleanup is completed. wait_for_cleanup_complete(); // Read the GC count while holding the Heap_lock int gc_count_before = SharedHeap::heap()->total_collections(); { MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back VM_G1CollectFull op(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) { IterateOopClosureRegionClosure blk(_g1_committed, cl); _hrs->iterate(&blk); } void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) { IterateOopClosureRegionClosure blk(mr, cl); _hrs->iterate(&blk); } // 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) { IterateObjectClosureRegionClosure blk(cl); _hrs->iterate(&blk); } 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 = (ParallelGCThreads > 0 ? 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) { 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, no more than half the region size, since we can't allow tlabs to // grow big enough to accomodate humongous objects. // We need to story it locally, since it might change between when we // test for NULL and when we use it later. ContiguousSpace* cur_alloc_space = _cur_alloc_region; if (cur_alloc_space == NULL) { return HeapRegion::GrainBytes/2; } else { return MAX2(MIN2(cur_alloc_space->free(), (size_t)(HeapRegion::GrainBytes/2)), (size_t)MinTLABSize); } } HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) { bool dummy; return G1CollectedHeap::mem_allocate(size, false, true, &dummy); } bool G1CollectedHeap::allocs_are_zero_filled() { return false; } size_t G1CollectedHeap::large_typearray_limit() { // FIXME return HeapRegion::GrainBytes/HeapWordSize; } size_t G1CollectedHeap::max_capacity() const { return _g1_committed.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) { guarantee(false, "NYI"); } void do_oop(oop *p) { oop obj = *p; assert(obj == NULL || !g1h->is_obj_dead(obj), "Dead object referenced by a not dead object"); } }; class VerifyObjsInRegionClosure: public ObjectClosure { G1CollectedHeap* _g1h; size_t _live_bytes; HeapRegion *_hr; public: VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) { _g1h = G1CollectedHeap::heap(); } void do_object(oop o) { VerifyLivenessOopClosure isLive(_g1h); assert(o != NULL, "Huh?"); if (!_g1h->is_obj_dead(o)) { o->oop_iterate(&isLive); if (!_hr->obj_allocated_since_prev_marking(o)) _live_bytes += (o->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 { public: bool _allow_dirty; bool _par; VerifyRegionClosure(bool allow_dirty, bool par = false) : _allow_dirty(allow_dirty), _par(par) {} bool doHeapRegion(HeapRegion* r) { guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue, "Should be unclaimed at verify points."); if (!r->continuesHumongous()) { VerifyObjsInRegionClosure not_dead_yet_cl(r); r->verify(_allow_dirty); r->object_iterate(¬_dead_yet_cl); guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(), "More live objects than counted in last complete marking."); } return false; } }; class VerifyRootsClosure: public OopsInGenClosure { private: G1CollectedHeap* _g1h; bool _failures; public: VerifyRootsClosure() : _g1h(G1CollectedHeap::heap()), _failures(false) { } bool failures() { return _failures; } void do_oop(narrowOop* p) { guarantee(false, "NYI"); } void do_oop(oop* p) { oop obj = *p; if (obj != NULL) { if (_g1h->is_obj_dead(obj)) { 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; } } } }; // This is the task used for parallel heap verification. class G1ParVerifyTask: public AbstractGangTask { private: G1CollectedHeap* _g1h; bool _allow_dirty; public: G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) : AbstractGangTask("Parallel verify task"), _g1h(g1h), _allow_dirty(allow_dirty) { } void work(int worker_i) { HandleMark hm; VerifyRegionClosure blk(_allow_dirty, true); _g1h->heap_region_par_iterate_chunked(&blk, worker_i, HeapRegion::ParVerifyClaimValue); } }; void G1CollectedHeap::verify(bool allow_dirty, bool silent) { if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { if (!silent) { gclog_or_tty->print("roots "); } VerifyRootsClosure rootsCl; process_strong_roots(false, SharedHeap::SO_AllClasses, &rootsCl, &rootsCl); rem_set()->invalidate(perm_gen()->used_region(), false); 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); int n_workers = workers()->total_workers(); set_par_threads(n_workers); workers()->run_task(&task); set_par_threads(0); 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); _hrs->iterate(&blk); } if (!silent) gclog_or_tty->print("remset "); rem_set()->verify(); guarantee(!rootsCl.failures(), "should not have had 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(gclog_or_tty); } void G1CollectedHeap::print_on(outputStream* st) const { PrintRegionClosure blk(st); _hrs->iterate(&blk); } void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { if (ParallelGCThreads > 0) { workers()->print_worker_threads(); } st->print("\"G1 concurrent mark GC Thread\" "); _cmThread->print(); st->cr(); st->print("\"G1 concurrent refinement GC Thread\" "); _cg1r->cg1rThread()->print_on(st); st->cr(); st->print("\"G1 zero-fill GC Thread\" "); _czft->print_on(st); st->cr(); } void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { if (ParallelGCThreads > 0) { workers()->threads_do(tc); } tc->do_thread(_cmThread); tc->do_thread(_cg1r->cg1rThread()); tc->do_thread(_czft); } void G1CollectedHeap::print_tracing_info() const { concurrent_g1_refine()->print_final_card_counts(); // 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 (SummarizeG1RSStats) { g1_rem_set()->print_summary_info(); } if (SummarizeG1ConcMark) { concurrent_mark()->print_summary_info(); } if (SummarizeG1ZFStats) { ConcurrentZFThread::print_summary_info(); } if (G1SummarizePopularity) { print_popularity_summary_info(); } g1_policy()->print_yg_surv_rate_info(); GCOverheadReporter::printGCOverhead(); 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 */) { if (PrintHeapAtGC){ gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections()); Universe::print(); } 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")); if (PrintHeapAtGC){ gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections()); Universe::print(); gclog_or_tty->print("} "); } } void G1CollectedHeap::do_collection_pause() { // Read the GC count while holding the Heap_lock // we need to do this _before_ wait_for_cleanup_complete(), to // ensure that we do not give up the heap lock and potentially // pick up the wrong count int gc_count_before = SharedHeap::heap()->total_collections(); // Don't want to do a GC pause while cleanup is being completed! wait_for_cleanup_complete(); g1_policy()->record_stop_world_start(); { MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back VM_G1IncCollectionPause op(gc_count_before); VMThread::execute(&op); } } void G1CollectedHeap::doConcurrentMark() { if (G1ConcMark) { 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); } 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() { HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set(); return g1_rset->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)); for (size_t i = 0; i < array_length; ++i) { guarantee( _surviving_young_words[i] == 0, "invariant" ); } } 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> void G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) { char verbose_str[128]; sprintf(verbose_str, "GC pause "); if (popular_region != NULL) strcat(verbose_str, "(popular)"); else if (g1_policy()->in_young_gc_mode()) { if (g1_policy()->full_young_gcs()) strcat(verbose_str, "(young)"); else strcat(verbose_str, "(partial)"); } bool reset_should_initiate_conc_mark = false; if (popular_region != NULL && g1_policy()->should_initiate_conc_mark()) { // we currently do not allow an initial mark phase to be piggy-backed // on a popular pause reset_should_initiate_conc_mark = true; g1_policy()->unset_should_initiate_conc_mark(); } if (g1_policy()->should_initiate_conc_mark()) strcat(verbose_str, " (initial-mark)"); GCCauseSetter x(this, (popular_region == NULL ? GCCause::_g1_inc_collection_pause : GCCause::_g1_pop_region_collection_pause)); // 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); ResourceMark rm; assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread"); guarantee(!is_gc_active(), "collection is not reentrant"); assert(regions_accounted_for(), "Region leakage!"); increment_gc_time_stamp(); if (g1_policy()->in_young_gc_mode()) { assert(check_young_list_well_formed(), "young list should be well formed"); } if (GC_locker::is_active()) { return; // GC is disabled (e.g. JNI GetXXXCritical operation) } bool abandoned = false; { // Call to jvmpi::post_class_unload_events must occur outside of active GC IsGCActiveMark x; gc_prologue(false); increment_total_collections(); #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()); // We want to turn off ref discovery, if necessary, and turn it back on // on again later if we do. 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(); GCOverheadReporter::recordSTWStart(start_time_sec); size_t start_used_bytes = used(); if (!G1ConcMark) { do_sync_mark(); } g1_policy()->record_collection_pause_start(start_time_sec, start_used_bytes); guarantee(_in_cset_fast_test == NULL, "invariant"); guarantee(_in_cset_fast_test_base == NULL, "invariant"); _in_cset_fast_test_length = max_regions(); _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length); memset(_in_cset_fast_test_base, false, _in_cset_fast_test_length * sizeof(bool)); // 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); #if SCAN_ONLY_VERBOSE _young_list->print(); #endif // SCAN_ONLY_VERBOSE if (g1_policy()->should_initiate_conc_mark()) { concurrent_mark()->checkpointRootsInitialPre(); } save_marks(); // We must do this before any possible evacuation that should propagate // marks, including evacuation of popular objects in a popular pause. 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(); assert(regions_accounted_for(), "Region leakage."); bool abandoned = false; if (mark_in_progress()) concurrent_mark()->newCSet(); // Now choose the CS. if (popular_region == NULL) { g1_policy()->choose_collection_set(); } else { // We may be evacuating a single region (for popularity). g1_policy()->record_popular_pause_preamble_start(); popularity_pause_preamble(popular_region); g1_policy()->record_popular_pause_preamble_end(); abandoned = (g1_policy()->collection_set() == NULL); // Now we allow more regions to be added (we have to collect // all popular regions). if (!abandoned) { g1_policy()->choose_collection_set(popular_region); } } // We may abandon a pause if we find no region that will fit in the MMU // pause. abandoned = (g1_policy()->collection_set() == NULL); // Nothing to do if we were unable to choose a collection set. if (!abandoned) { #if G1_REM_SET_LOGGING gclog_or_tty->print_cr("\nAfter pause, heap:"); print(); #endif 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(); FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base); // this is more for peace of mind; we're nulling them here and // we're expecting them to be null at the beginning of the next GC _in_cset_fast_test = NULL; _in_cset_fast_test_base = NULL; if (popular_region != NULL) { // We have to wait until now, because we don't want the region to // be rescheduled for pop-evac during RS update. popular_region->set_popular_pending(false); } release_gc_alloc_regions(false /* totally */); cleanup_surviving_young_words(); if (g1_policy()->in_young_gc_mode()) { _young_list->reset_sampled_info(); assert(check_young_list_empty(true), "young list should be empty"); #if SCAN_ONLY_VERBOSE _young_list->print(); #endif // SCAN_ONLY_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(); } } else { COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); } 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()->should_initiate_conc_mark()) { concurrent_mark()->checkpointRootsInitialPost(); set_marking_started(); doConcurrentMark(); } #if SCAN_ONLY_VERBOSE _young_list->print(); #endif // SCAN_ONLY_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); GCOverheadReporter::recordSTWEnd(end_time_sec); g1_policy()->record_collection_pause_end(popular_region != NULL, abandoned); assert(regions_accounted_for(), "Region leakage."); 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(); expand(expand_bytes); } } if (mark_in_progress()) { concurrent_mark()->update_g1_committed(); } #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif gc_epilogue(false); } assert(verify_region_lists(), "Bad region lists."); if (reset_should_initiate_conc_mark) g1_policy()->set_should_initiate_conc_mark(); if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) { gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum); print_tracing_info(); vm_exit(-1); } } 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"); 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 (ParallelGCThreads > 0) { // 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() || par_alloc_during_gc_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(Thread::current()->is_VM_thread(), "Precondition"); 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); } } if (r->is_empty()) { ++_free_regions; } } #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"); // 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()) { // we will discard the current GC alloc region if it's in the // collection set (it can happen!), if it's already full (no // point in using it), or if it's empty (this means that it // was emptied during a cleanup and it should be on the free // list now). alloc_region = NULL; } } if (alloc_region == NULL) { // we will get a new GC alloc region alloc_region = newAllocRegionWithExpansion(ap, 0); } 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; if (r != NULL) { // we retain nothing on _gc_alloc_regions between GCs set_gc_alloc_region(ap, NULL); _gc_alloc_region_counts[ap] = 0; if (r->is_empty()) { // we didn't actually allocate anything in it; let's just put // it on the free list MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); r->set_zero_fill_complete(); put_free_region_on_list_locked(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"); // Don't have to delete, since the scan stack is a resource object. _evac_failure_scan_stack = NULL; } // *** Sequential G1 Evacuation HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) { HeapRegion* alloc_region = _gc_alloc_regions[purpose]; // let the caller handle alloc failure if (alloc_region == NULL) return NULL; assert(isHumongous(word_size) || !alloc_region->isHumongous(), "Either the object is humongous or the region isn't"); HeapWord* block = alloc_region->allocate(word_size); if (block == NULL) { block = allocate_during_gc_slow(purpose, alloc_region, false, word_size); } return block; } 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, "NYI"); } 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 UpdateRSetImmediate : public OopsInHeapRegionClosure { private: G1CollectedHeap* _g1; G1RemSet* _g1_rem_set; public: UpdateRSetImmediate(G1CollectedHeap* g1) : _g1(g1), _g1_rem_set(g1->g1_rem_set()) {} void do_oop(narrowOop* p) { guarantee(false, "NYI"); } void do_oop(oop* p) { assert(_from->is_in_reserved(p), "paranoia"); if (*p != NULL && !_from->is_survivor()) { _g1_rem_set->par_write_ref(_from, p, 0); } } }; 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) {} void do_oop(narrowOop* p) { guarantee(false, "NYI"); } void do_oop(oop* p) { assert(_from->is_in_reserved(p), "paranoia"); if (!_from->is_in_reserved(*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, OopsInHeapRegionClosure* cl) : _g1(g1), _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; } // 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. void do_object(oop obj) { 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); 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!"); RemoveSelfPointerClosure rspc(_g1h, cl); if (cur->evacuation_failed()) { assert(cur->in_collection_set(), "bad CS"); 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."); assert(_objs_with_preserved_marks->length() == _preserved_marks_of_objs->length(), "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); } } void G1CollectedHeap::handle_evacuation_failure(oop old) { markOop m = old->mark(); // forward to self assert(!old->is_forwarded(), "precondition"); old->forward_to(old); handle_evacuation_failure_common(old, m); } 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 (G1TraceRegions) { gclog_or_tty->print("evacuation failed 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) { if (m != markOopDesc::prototype()) { 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) { 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) { MutexLockerEx x(par_alloc_during_gc_lock(), Mutex::_no_safepoint_check_flag); 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) { 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 = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/); // 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."); // We used to assert that the region was zero-filled here, but no // longer. // 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 < (size_t)oopDesc::header_size()) return; // Otherwise, try to claim it. block = r->par_allocate(free_words); } while (block == NULL); fill_with_object(block, free_words); } #define use_local_bitmaps 1 #define verify_local_bitmaps 0 #ifndef PRODUCT class GCLabBitMap; class GCLabBitMapClosure: public BitMapClosure { private: ConcurrentMark* _cm; GCLabBitMap* _bitmap; public: GCLabBitMapClosure(ConcurrentMark* cm, GCLabBitMap* bitmap) { _cm = cm; _bitmap = bitmap; } virtual bool do_bit(size_t offset); }; #endif // PRODUCT #define oop_buffer_length 256 class GCLabBitMap: public BitMap { private: ConcurrentMark* _cm; int _shifter; size_t _bitmap_word_covers_words; // beginning of the heap HeapWord* _heap_start; // this is the actual start of the GCLab HeapWord* _real_start_word; // this is the actual end of the GCLab HeapWord* _real_end_word; // this is the first word, possibly located before the actual start // of the GCLab, that corresponds to the first bit of the bitmap HeapWord* _start_word; // size of a GCLab in words size_t _gclab_word_size; static int shifter() { return MinObjAlignment - 1; } // how many heap words does a single bitmap word corresponds to? static size_t bitmap_word_covers_words() { return BitsPerWord << shifter(); } static size_t gclab_word_size() { return ParallelGCG1AllocBufferSize / HeapWordSize; } static size_t bitmap_size_in_bits() { size_t bits_in_bitmap = gclab_word_size() >> shifter(); // We are going to ensure that the beginning of a word in this // bitmap also corresponds to the beginning of a word in the // global marking bitmap. To handle the case where a GCLab // starts from the middle of the bitmap, we need to add enough // space (i.e. up to a bitmap word) to ensure that we have // enough bits in the bitmap. return bits_in_bitmap + BitsPerWord - 1; } public: GCLabBitMap(HeapWord* heap_start) : BitMap(bitmap_size_in_bits()), _cm(G1CollectedHeap::heap()->concurrent_mark()), _shifter(shifter()), _bitmap_word_covers_words(bitmap_word_covers_words()), _heap_start(heap_start), _gclab_word_size(gclab_word_size()), _real_start_word(NULL), _real_end_word(NULL), _start_word(NULL) { guarantee( size_in_words() >= bitmap_size_in_words(), "just making sure"); } inline unsigned heapWordToOffset(HeapWord* addr) { unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter; assert(offset < size(), "offset should be within bounds"); return offset; } inline HeapWord* offsetToHeapWord(size_t offset) { HeapWord* addr = _start_word + (offset << _shifter); assert(_real_start_word <= addr && addr < _real_end_word, "invariant"); return addr; } bool fields_well_formed() { bool ret1 = (_real_start_word == NULL) && (_real_end_word == NULL) && (_start_word == NULL); if (ret1) return true; bool ret2 = _real_start_word >= _start_word && _start_word < _real_end_word && (_real_start_word + _gclab_word_size) == _real_end_word && (_start_word + _gclab_word_size + _bitmap_word_covers_words) > _real_end_word; return ret2; } inline bool mark(HeapWord* addr) { guarantee(use_local_bitmaps, "invariant"); assert(fields_well_formed(), "invariant"); if (addr >= _real_start_word && addr < _real_end_word) { assert(!isMarked(addr), "should not have already been marked"); // first mark it on the bitmap at_put(heapWordToOffset(addr), true); return true; } else { return false; } } inline bool isMarked(HeapWord* addr) { guarantee(use_local_bitmaps, "invariant"); assert(fields_well_formed(), "invariant"); return at(heapWordToOffset(addr)); } void set_buffer(HeapWord* start) { guarantee(use_local_bitmaps, "invariant"); clear(); assert(start != NULL, "invariant"); _real_start_word = start; _real_end_word = start + _gclab_word_size; size_t diff = pointer_delta(start, _heap_start) % _bitmap_word_covers_words; _start_word = start - diff; assert(fields_well_formed(), "invariant"); } #ifndef PRODUCT void verify() { // verify that the marks have been propagated GCLabBitMapClosure cl(_cm, this); iterate(&cl); } #endif // PRODUCT void retire() { guarantee(use_local_bitmaps, "invariant"); assert(fields_well_formed(), "invariant"); if (_start_word != NULL) { CMBitMap* mark_bitmap = _cm->nextMarkBitMap(); // this means that the bitmap was set up for the GCLab assert(_real_start_word != NULL && _real_end_word != NULL, "invariant"); mark_bitmap->mostly_disjoint_range_union(this, 0, // always start from the start of the bitmap _start_word, size_in_words()); _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word)); #ifndef PRODUCT if (use_local_bitmaps && verify_local_bitmaps) verify(); #endif // PRODUCT } else { assert(_real_start_word == NULL && _real_end_word == NULL, "invariant"); } } static size_t bitmap_size_in_words() { return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord; } }; #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 class G1ParGCAllocBuffer: public ParGCAllocBuffer { private: bool _retired; bool _during_marking; GCLabBitMap _bitmap; public: G1ParGCAllocBuffer() : ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize), _during_marking(G1CollectedHeap::heap()->mark_in_progress()), _bitmap(G1CollectedHeap::heap()->reserved_region().start()), _retired(false) { } inline bool mark(HeapWord* addr) { guarantee(use_local_bitmaps, "invariant"); assert(_during_marking, "invariant"); return _bitmap.mark(addr); } inline void set_buf(HeapWord* buf) { if (use_local_bitmaps && _during_marking) _bitmap.set_buffer(buf); ParGCAllocBuffer::set_buf(buf); _retired = false; } inline void retire(bool end_of_gc, bool retain) { if (_retired) return; if (use_local_bitmaps && _during_marking) { _bitmap.retire(); } ParGCAllocBuffer::retire(end_of_gc, retain); _retired = true; } }; class G1ParScanThreadState : public StackObj { protected: G1CollectedHeap* _g1h; RefToScanQueue* _refs; DirtyCardQueue _dcq; CardTableModRefBS* _ct_bs; G1RemSet* _g1_rem; typedef GrowableArray<oop*> OverflowQueue; OverflowQueue* _overflowed_refs; G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount]; ageTable _age_table; size_t _alloc_buffer_waste; size_t _undo_waste; OopsInHeapRegionClosure* _evac_failure_cl; G1ParScanHeapEvacClosure* _evac_cl; G1ParScanPartialArrayClosure* _partial_scan_cl; int _hash_seed; int _queue_num; int _term_attempts; #if G1_DETAILED_STATS int _pushes, _pops, _steals, _steal_attempts; int _overflow_pushes; #endif double _start; double _start_strong_roots; double _strong_roots_time; double _start_term; double _term_time; // Map from young-age-index (0 == not young, 1 is youngest) to // surviving words. base is what we get back from the malloc call size_t* _surviving_young_words_base; // this points into the array, as we use the first few entries for padding size_t* _surviving_young_words; #define PADDING_ELEM_NUM (64 / sizeof(size_t)) void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } void add_to_undo_waste(size_t waste) { _undo_waste += waste; } DirtyCardQueue& dirty_card_queue() { return _dcq; } CardTableModRefBS* ctbs() { return _ct_bs; } void immediate_rs_update(HeapRegion* from, oop* p, int tid) { if (!from->is_survivor()) { _g1_rem->par_write_ref(from, p, tid); } } void deferred_rs_update(HeapRegion* from, oop* p, int tid) { // If the new value of the field points to the same region or // is the to-space, we don't need to include it in the Rset updates. if (!from->is_in_reserved(*p) && !from->is_survivor()) { size_t card_index = ctbs()->index_for(p); // If the card hasn't been added to the buffer, do it. if (ctbs()->mark_card_deferred(card_index)) { dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); } } } public: 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), _age_table(false), #if G1_DETAILED_STATS _pushes(0), _pops(0), _steals(0), _steal_attempts(0), _overflow_pushes(0), #endif _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)); _overflowed_refs = new OverflowQueue(10); _start = os::elapsedTime(); } ~G1ParScanThreadState() { FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); } RefToScanQueue* refs() { return _refs; } OverflowQueue* overflowed_refs() { return _overflowed_refs; } ageTable* age_table() { return &_age_table; } G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { return &_alloc_buffers[purpose]; } size_t alloc_buffer_waste() { return _alloc_buffer_waste; } size_t undo_waste() { return _undo_waste; } void push_on_queue(oop* ref) { assert(ref != NULL, "invariant"); assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant"); if (!refs()->push(ref)) { overflowed_refs()->push(ref); IF_G1_DETAILED_STATS(note_overflow_push()); } else { IF_G1_DETAILED_STATS(note_push()); } } void pop_from_queue(oop*& ref) { if (!refs()->pop_local(ref)) { ref = NULL; } else { assert(ref != NULL, "invariant"); assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant"); IF_G1_DETAILED_STATS(note_pop()); } } void pop_from_overflow_queue(oop*& ref) { ref = overflowed_refs()->pop(); } int refs_to_scan() { return refs()->size(); } int overflowed_refs_to_scan() { return overflowed_refs()->length(); } void update_rs(HeapRegion* from, oop* p, int tid) { if (G1DeferredRSUpdate) { deferred_rs_update(from, p, tid); } else { immediate_rs_update(from, p, tid); } } HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { HeapWord* obj = NULL; if (word_sz * 100 < (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) * ParallelGCBufferWastePct) { G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); add_to_alloc_buffer_waste(alloc_buf->words_remaining()); alloc_buf->retire(false, false); HeapWord* buf = _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize); if (buf == NULL) return NULL; // Let caller handle allocation failure. // Otherwise. alloc_buf->set_buf(buf); obj = alloc_buf->allocate(word_sz); assert(obj != NULL, "buffer was definitely big enough..."); } else { obj = _g1h->par_allocate_during_gc(purpose, word_sz); } return obj; } HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); if (obj != NULL) return obj; return allocate_slow(purpose, word_sz); } void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { if (alloc_buffer(purpose)->contains(obj)) { guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1), "should contain whole object"); alloc_buffer(purpose)->undo_allocation(obj, word_sz); } else { CollectedHeap::fill_with_object(obj, word_sz); add_to_undo_waste(word_sz); } } void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { _evac_failure_cl = evac_failure_cl; } OopsInHeapRegionClosure* evac_failure_closure() { return _evac_failure_cl; } void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { _evac_cl = evac_cl; } void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { _partial_scan_cl = partial_scan_cl; } int* hash_seed() { return &_hash_seed; } int queue_num() { return _queue_num; } int term_attempts() { return _term_attempts; } void note_term_attempt() { _term_attempts++; } #if G1_DETAILED_STATS int pushes() { return _pushes; } int pops() { return _pops; } int steals() { return _steals; } int steal_attempts() { return _steal_attempts; } int overflow_pushes() { return _overflow_pushes; } void note_push() { _pushes++; } void note_pop() { _pops++; } void note_steal() { _steals++; } void note_steal_attempt() { _steal_attempts++; } void note_overflow_push() { _overflow_pushes++; } #endif void start_strong_roots() { _start_strong_roots = os::elapsedTime(); } void end_strong_roots() { _strong_roots_time += (os::elapsedTime() - _start_strong_roots); } double strong_roots_time() { return _strong_roots_time; } void start_term_time() { note_term_attempt(); _start_term = os::elapsedTime(); } void end_term_time() { _term_time += (os::elapsedTime() - _start_term); } double term_time() { return _term_time; } double elapsed() { return os::elapsedTime() - _start; } size_t* surviving_young_words() { // We add on to hide entry 0 which accumulates surviving words for // age -1 regions (i.e. non-young ones) return _surviving_young_words; } void retire_alloc_buffers() { for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { size_t waste = _alloc_buffers[ap].words_remaining(); add_to_alloc_buffer_waste(waste); _alloc_buffers[ap].retire(true, false); } } private: void deal_with_reference(oop* ref_to_scan) { if (has_partial_array_mask(ref_to_scan)) { _partial_scan_cl->do_oop_nv(ref_to_scan); } else { // Note: we can use "raw" versions of "region_containing" because // "obj_to_scan" is definitely in the heap, and is not in a // humongous region. HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); _evac_cl->set_region(r); _evac_cl->do_oop_nv(ref_to_scan); } } public: void trim_queue() { // I've replicated the loop twice, first to drain the overflow // queue, second to drain the task queue. This is better than // having a single loop, which checks both conditions and, inside // it, either pops the overflow queue or the task queue, as each // loop is tighter. Also, the decision to drain the overflow queue // first is not arbitrary, as the overflow queue is not visible // to the other workers, whereas the task queue is. So, we want to // drain the "invisible" entries first, while allowing the other // workers to potentially steal the "visible" entries. while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) { while (overflowed_refs_to_scan() > 0) { oop *ref_to_scan = NULL; pop_from_overflow_queue(ref_to_scan); assert(ref_to_scan != NULL, "invariant"); // We shouldn't have pushed it on the queue if it was not // pointing into the CSet. assert(ref_to_scan != NULL, "sanity"); assert(has_partial_array_mask(ref_to_scan) || _g1h->obj_in_cs(*ref_to_scan), "sanity"); deal_with_reference(ref_to_scan); } while (refs_to_scan() > 0) { oop *ref_to_scan = NULL; pop_from_queue(ref_to_scan); if (ref_to_scan != NULL) { // We shouldn't have pushed it on the queue if it was not // pointing into the CSet. assert(has_partial_array_mask(ref_to_scan) || _g1h->obj_in_cs(*ref_to_scan), "sanity"); deal_with_reference(ref_to_scan); } } } } }; 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) { } // This closure is applied to the fields of the objects that have just been copied. // Should probably be made inline and moved in g1OopClosures.inline.hpp. void G1ParScanClosure::do_oop_nv(oop* p) { oop obj = *p; if (obj != NULL) { if (_g1->in_cset_fast_test(obj)) { // We're not going to even bother checking whether the object is // already forwarded or not, as this usually causes an immediate // stall. We'll try to prefetch the object (for write, given that // we might need to install the forwarding reference) and we'll // get back to it when pop it from the queue Prefetch::write(obj->mark_addr(), 0); Prefetch::read(obj->mark_addr(), (HeapWordSize*2)); // slightly paranoid test; I'm trying to catch potential // problems before we go into push_on_queue to know where the // problem is coming from assert(obj == *p, "the value of *p should not have changed"); _par_scan_state->push_on_queue(p); } else { _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num()); } } } void G1ParCopyHelper::mark_forwardee(oop* 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. oop thisOop = *p; if (thisOop != NULL) { assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)), "shouldn't still be in the CSet if evacuation didn't fail."); HeapWord* addr = (HeapWord*)thisOop; 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); _par_scan_state->push_on_queue(set_partial_array_mask(old)); } 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, bool skip_cset_test> void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_forwardee, skip_cset_test>::do_oop_work(oop* p) { oop obj = *p; assert(barrier != G1BarrierRS || obj != NULL, "Precondition: G1BarrierRS implies obj is nonNull"); // The only time we skip the cset test is when we're scanning // references popped from the queue. And we only push on the queue // references that we know point into the cset, so no point in // checking again. But we'll leave an assert here for peace of mind. assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant"); // here the null check is implicit in the cset_fast_test() test if (skip_cset_test || _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()) { *p = obj->forwardee(); } else { *p = copy_to_survivor_space(obj); } // 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()); } } // When scanning moved objs, must look at all oops. 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, true>::do_oop_work(oop* p); template<class T> void G1ParScanPartialArrayClosure::process_array_chunk( oop obj, int start, int end) { // process our set of indices (include header in first chunk) assert(start < end, "invariant"); T* const base = (T*)objArrayOop(obj)->base(); T* const start_addr = (start == 0) ? (T*) obj : base + start; T* const end_addr = base + end; MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr); _scanner.set_region(_g1->heap_region_containing(obj)); obj->oop_iterate(&_scanner, mr); } void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) { assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops"); 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. _par_scan_state->push_on_queue(set_partial_array_mask(old)); } else { // Restore length so that the heap remains parsable in // case of evacuation failure. arrayOop(old)->set_length(end); } // process our set of indices (include header in first chunk) process_array_chunk<oop>(obj, start, end); } int G1ScanAndBalanceClosure::_nq = 0; 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() { G1ParScanThreadState* pss = par_scan_state(); while (true) { oop* ref_to_scan; pss->trim_queue(); IF_G1_DETAILED_STATS(pss->note_steal_attempt()); if (queues()->steal(pss->queue_num(), pss->hash_seed(), ref_to_scan)) { IF_G1_DETAILED_STATS(pss->note_steal()); // slightly paranoid tests; I'm trying to catch potential // problems before we go into push_on_queue to know where the // problem is coming from assert(ref_to_scan != NULL, "invariant"); assert(has_partial_array_mask(ref_to_scan) || _g1h->obj_in_cs(*ref_to_scan), "invariant"); pss->push_on_queue(ref_to_scan); continue; } pss->start_term_time(); if (terminator()->offer_termination()) break; pss->end_term_time(); } pss->end_term_time(); pss->retire_alloc_buffers(); } }; class G1ParTask : public AbstractGangTask { protected: G1CollectedHeap* _g1h; RefToScanQueueSet *_queues; ParallelTaskTerminator _terminator; 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) {} RefToScanQueueSet* queues() { return _queues; } RefToScanQueue *work_queue(int i) { return queues()->queue(i); } void work(int i) { 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); 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; OopsInHeapRegionClosure *scan_so_cl; if (_g1h->g1_policy()->should_initiate_conc_mark()) { scan_root_cl = &scan_mark_root_cl; scan_perm_cl = &scan_mark_perm_cl; scan_so_cl = &scan_mark_heap_rs_cl; } else { scan_root_cl = &only_scan_root_cl; scan_perm_cl = &only_scan_perm_cl; scan_so_cl = &only_scan_heap_rs_cl; } pss.start_strong_roots(); _g1h->g1_process_strong_roots(/* not collecting perm */ false, SharedHeap::SO_AllClasses, scan_root_cl, &only_scan_heap_rs_cl, scan_so_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_time(i, term_ms); } if (G1UseSurvivorSpace) { _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(); MutexLocker x(stats_lock()); if (ParallelGCVerbose) { gclog_or_tty->print("Thread %d complete:\n", i); #if G1_DETAILED_STATS gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n", pss.pushes(), pss.pops(), pss.overflow_pushes(), pss.steals(), pss.steal_attempts()); #endif double elapsed = pss.elapsed(); double strong_roots = pss.strong_roots_time(); double term = pss.term_time(); gclog_or_tty->print(" Elapsed: %7.2f ms.\n" " Strong roots: %7.2f ms (%6.2f%%)\n" " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n", elapsed * 1000.0, strong_roots * 1000.0, (strong_roots*100.0/elapsed), term * 1000.0, (term*100.0/elapsed), pss.term_attempts()); size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste(); gclog_or_tty->print(" Waste: %8dK\n" " Alloc Buffer: %8dK\n" " Undo: %8dK\n", (total_waste * HeapWordSize) / K, (pss.alloc_buffer_waste() * HeapWordSize) / K, (pss.undo_waste() * HeapWordSize) / K); } assert(pss.refs_to_scan() == 0, "Task queue should be empty"); assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty"); } }; // *** Common G1 Evacuation Stuff class G1CountClosure: public OopsInHeapRegionClosure { public: int n; G1CountClosure() : n(0) {} void do_oop(narrowOop* p) { guarantee(false, "NYI"); } void do_oop(oop* p) { oop obj = *p; assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj), "Rem set closure called on non-rem-set pointer."); n++; } }; static G1CountClosure count_closure; void G1CollectedHeap:: g1_process_strong_roots(bool collecting_perm_gen, SharedHeap::ScanningOption so, OopClosure* scan_non_heap_roots, OopsInHeapRegionClosure* scan_rs, OopsInHeapRegionClosure* scan_so, 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()); process_strong_roots(collecting_perm_gen, so, &buf_scan_non_heap_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(); if (G1VerifyRemSet) { // :::: FIXME :::: // The stupid remembered set doesn't know how to filter out dead // objects, which the smart one does, and so when it is created // and then compared the number of entries in each differs and // the verification code fails. guarantee(false, "verification code is broken, see note"); // Let's make sure that the current rem set agrees with the stupidest // one possible! bool refs_enabled = ref_processor()->discovery_enabled(); if (refs_enabled) ref_processor()->disable_discovery(); StupidG1RemSet stupid(this); count_closure.n = 0; stupid.oops_into_collection_set_do(&count_closure, worker_i); int stupid_n = count_closure.n; count_closure.n = 0; g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i); guarantee(count_closure.n == stupid_n, "Old and new rem sets differ."); gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n); if (refs_enabled) ref_processor()->enable_discovery(); } if (scan_so != NULL) { scan_scan_only_set(scan_so, worker_i); } // 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)) { 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::scan_scan_only_region(HeapRegion* r, OopsInHeapRegionClosure* oc, int worker_i) { HeapWord* startAddr = r->bottom(); HeapWord* endAddr = r->used_region().end(); oc->set_region(r); HeapWord* p = r->bottom(); HeapWord* t = r->top(); guarantee( p == r->next_top_at_mark_start(), "invariant" ); while (p < t) { oop obj = oop(p); p += obj->oop_iterate(oc); } } void G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc, int worker_i) { double start = os::elapsedTime(); BufferingOopsInHeapRegionClosure boc(oc); FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc); FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark()); OopsInHeapRegionClosure *foc; if (g1_policy()->should_initiate_conc_mark()) foc = &scan_and_mark; else foc = &scan_only; HeapRegion* hr; int n = 0; while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) { scan_scan_only_region(hr, foc, worker_i); ++n; } boc.done(); double closure_app_s = boc.closure_app_seconds(); g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0); double ms = (os::elapsedTime() - start - closure_app_s)*1000.0; g1_policy()->record_scan_only_time(worker_i, ms, n); } void G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure, OopClosure* non_root_closure) { SharedHeap::process_weak_roots(root_closure, non_root_closure); } class SaveMarksClosure: public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* r) { r->save_marks(); return false; } }; void G1CollectedHeap::save_marks() { if (ParallelGCThreads == 0) { 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); 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); change_strong_roots_parity(); // In preparation for parallel strong roots. 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 (ParallelGCThreads > 0) { // The individual threads will set their evac-failure closures. workers()->run_task(&g1_par_task); } else { 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(); { G1IsAliveClosure is_alive(this); G1KeepAliveClosure keep_alive(this); JNIHandles::weak_oops_do(&is_alive, &keep_alive); } g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 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(" (evacuation failed)"); } 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(); JavaThread::dirty_card_queue_set().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(HeapRegion* hr) { size_t pre_used = 0; size_t cleared_h_regions = 0; size_t freed_regions = 0; UncleanRegionList local_list; HeapWord* start = hr->bottom(); HeapWord* end = hr->prev_top_at_mark_start(); size_t used_bytes = hr->used(); size_t live_bytes = hr->max_live_bytes(); if (used_bytes > 0) { guarantee( live_bytes <= used_bytes, "invariant" ); } else { guarantee( live_bytes == 0, "invariant" ); } size_t garbage_bytes = used_bytes - live_bytes; if (garbage_bytes > 0) g1_policy()->decrease_known_garbage_bytes(garbage_bytes); free_region_work(hr, pre_used, cleared_h_regions, freed_regions, &local_list); finish_free_region_work(pre_used, cleared_h_regions, freed_regions, &local_list); } void G1CollectedHeap::free_region_work(HeapRegion* hr, size_t& pre_used, size_t& cleared_h_regions, size_t& freed_regions, UncleanRegionList* list, bool par) { assert(!hr->popular(), "should not free popular regions"); pre_used += hr->used(); if (hr->isHumongous()) { assert(hr->startsHumongous(), "Only the start of a humongous region should be freed."); int ind = _hrs->find(hr); assert(ind != -1, "Should have an index."); // Clear the start region. hr->hr_clear(par, true /*clear_space*/); list->insert_before_head(hr); cleared_h_regions++; freed_regions++; // Clear any continued regions. ind++; while ((size_t)ind < n_regions()) { HeapRegion* hrc = _hrs->at(ind); if (!hrc->continuesHumongous()) break; // Otherwise, does continue the H region. assert(hrc->humongous_start_region() == hr, "Huh?"); hrc->hr_clear(par, true /*clear_space*/); cleared_h_regions++; freed_regions++; list->insert_before_head(hrc); ind++; } } else { hr->hr_clear(par, true /*clear_space*/); list->insert_before_head(hr); freed_regions++; // If we're using clear2, this should not be enabled. // assert(!hr->in_cohort(), "Can't be both free and in a cohort."); } } void G1CollectedHeap::finish_free_region_work(size_t pre_used, size_t cleared_h_regions, size_t freed_regions, UncleanRegionList* list) { if (list != NULL && list->sz() > 0) { prepend_region_list_on_unclean_list(list); } // Acquire a lock, if we're parallel, to update possibly-shared // variables. Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL; { MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag); _summary_bytes_used -= pre_used; _num_humongous_regions -= (int) cleared_h_regions; _free_regions += freed_regions; } } 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(); } } void G1CollectedHeap::cleanUpCardTable() { CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set()); double start = os::elapsedTime(); ct_bs->clear(_g1_committed); // now, redirty the cards of the scan-only and survivor regions // (it seemed faster to do it this way, instead of iterating over // all regions and then clearing / dirtying as approprite) dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region()); dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region()); double elapsed = os::elapsedTime() - start; g1_policy()->record_clear_ct_time( elapsed * 1000.0); } void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) { // First do any popular regions. HeapRegion* hr; while ((hr = popular_region_to_evac()) != NULL) { evac_popular_region(hr); } // Now do heuristic pauses. if (g1_policy()->should_do_collection_pause(word_size)) { do_collection_pause(); } } void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) { double young_time_ms = 0.0; double non_young_time_ms = 0.0; 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) { 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 { if (!cur->is_on_free_list()) { 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); } 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); } else { guarantee( !cur->is_scan_only(), "should not be scan only" ); 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; policy->record_young_free_cset_time_ms(young_time_ms); policy->record_non_young_free_cset_time_ms(non_young_time_ms); } HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) { assert(ZF_mon->owned_by_self(), "Precondition"); HeapRegion* res = pop_unclean_region_list_locked(); if (res != NULL) { assert(!res->continuesHumongous() && res->zero_fill_state() != HeapRegion::Allocated, "Only free regions on unclean list."); if (zero_filled) { res->ensure_zero_filled_locked(); res->set_zero_fill_allocated(); } } return res; } HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) { MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag); return alloc_region_from_unclean_list_locked(zero_filled); } void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); put_region_on_unclean_list_locked(r); if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread. } void G1CollectedHeap::set_unclean_regions_coming(bool b) { MutexLockerEx x(Cleanup_mon); set_unclean_regions_coming_locked(b); } void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) { assert(Cleanup_mon->owned_by_self(), "Precondition"); _unclean_regions_coming = b; // Wake up mutator threads that might be waiting for completeCleanup to // finish. if (!b) Cleanup_mon->notify_all(); } void G1CollectedHeap::wait_for_cleanup_complete() { MutexLockerEx x(Cleanup_mon); wait_for_cleanup_complete_locked(); } void G1CollectedHeap::wait_for_cleanup_complete_locked() { assert(Cleanup_mon->owned_by_self(), "precondition"); while (_unclean_regions_coming) { Cleanup_mon->wait(); } } void G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) { assert(ZF_mon->owned_by_self(), "precondition."); _unclean_region_list.insert_before_head(r); } void G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); prepend_region_list_on_unclean_list_locked(list); if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread. } void G1CollectedHeap:: prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) { assert(ZF_mon->owned_by_self(), "precondition."); _unclean_region_list.prepend_list(list); } HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() { assert(ZF_mon->owned_by_self(), "precondition."); HeapRegion* res = _unclean_region_list.pop(); if (res != NULL) { // Inform ZF thread that there's a new unclean head. if (_unclean_region_list.hd() != NULL && should_zf()) ZF_mon->notify_all(); } return res; } HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() { assert(ZF_mon->owned_by_self(), "precondition."); return _unclean_region_list.hd(); } bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() { assert(ZF_mon->owned_by_self(), "Precondition"); HeapRegion* r = peek_unclean_region_list_locked(); if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) { // Result of below must be equal to "r", since we hold the lock. (void)pop_unclean_region_list_locked(); put_free_region_on_list_locked(r); return true; } else { return false; } } bool G1CollectedHeap::move_cleaned_region_to_free_list() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); return move_cleaned_region_to_free_list_locked(); } void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) { assert(ZF_mon->owned_by_self(), "precondition."); assert(_free_region_list_size == free_region_list_length(), "Inv"); assert(r->zero_fill_state() == HeapRegion::ZeroFilled, "Regions on free list must be zero filled"); assert(!r->isHumongous(), "Must not be humongous."); assert(r->is_empty(), "Better be empty"); assert(!r->is_on_free_list(), "Better not already be on free list"); assert(!r->is_on_unclean_list(), "Better not already be on unclean list"); r->set_on_free_list(true); r->set_next_on_free_list(_free_region_list); _free_region_list = r; _free_region_list_size++; assert(_free_region_list_size == free_region_list_length(), "Inv"); } void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); put_free_region_on_list_locked(r); } HeapRegion* G1CollectedHeap::pop_free_region_list_locked() { assert(ZF_mon->owned_by_self(), "precondition."); assert(_free_region_list_size == free_region_list_length(), "Inv"); HeapRegion* res = _free_region_list; if (res != NULL) { _free_region_list = res->next_from_free_list(); _free_region_list_size--; res->set_on_free_list(false); res->set_next_on_free_list(NULL); assert(_free_region_list_size == free_region_list_length(), "Inv"); } return res; } HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) { // By self, or on behalf of self. assert(Heap_lock->is_locked(), "Precondition"); HeapRegion* res = NULL; bool first = true; while (res == NULL) { if (zero_filled || !first) { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); res = pop_free_region_list_locked(); if (res != NULL) { assert(!res->zero_fill_is_allocated(), "No allocated regions on free list."); res->set_zero_fill_allocated(); } else if (!first) { break; // We tried both, time to return NULL. } } if (res == NULL) { res = alloc_region_from_unclean_list(zero_filled); } assert(res == NULL || !zero_filled || res->zero_fill_is_allocated(), "We must have allocated the region we're returning"); first = false; } return res; } void G1CollectedHeap::remove_allocated_regions_from_lists() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); { HeapRegion* prev = NULL; HeapRegion* cur = _unclean_region_list.hd(); while (cur != NULL) { HeapRegion* next = cur->next_from_unclean_list(); if (cur->zero_fill_is_allocated()) { // Remove from the list. if (prev == NULL) { (void)_unclean_region_list.pop(); } else { _unclean_region_list.delete_after(prev); } cur->set_on_unclean_list(false); cur->set_next_on_unclean_list(NULL); } else { prev = cur; } cur = next; } assert(_unclean_region_list.sz() == unclean_region_list_length(), "Inv"); } { HeapRegion* prev = NULL; HeapRegion* cur = _free_region_list; while (cur != NULL) { HeapRegion* next = cur->next_from_free_list(); if (cur->zero_fill_is_allocated()) { // Remove from the list. if (prev == NULL) { _free_region_list = cur->next_from_free_list(); } else { prev->set_next_on_free_list(cur->next_from_free_list()); } cur->set_on_free_list(false); cur->set_next_on_free_list(NULL); _free_region_list_size--; } else { prev = cur; } cur = next; } assert(_free_region_list_size == free_region_list_length(), "Inv"); } } bool G1CollectedHeap::verify_region_lists() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); return verify_region_lists_locked(); } bool G1CollectedHeap::verify_region_lists_locked() { HeapRegion* unclean = _unclean_region_list.hd(); while (unclean != NULL) { guarantee(unclean->is_on_unclean_list(), "Well, it is!"); guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!"); guarantee(unclean->zero_fill_state() != HeapRegion::Allocated, "Everything else is possible."); unclean = unclean->next_from_unclean_list(); } guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv"); HeapRegion* free_r = _free_region_list; while (free_r != NULL) { assert(free_r->is_on_free_list(), "Well, it is!"); assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!"); switch (free_r->zero_fill_state()) { case HeapRegion::NotZeroFilled: case HeapRegion::ZeroFilling: guarantee(false, "Should not be on free list."); break; default: // Everything else is possible. break; } free_r = free_r->next_from_free_list(); } guarantee(_free_region_list_size == free_region_list_length(), "Inv"); // If we didn't do an assertion... return true; } size_t G1CollectedHeap::free_region_list_length() { assert(ZF_mon->owned_by_self(), "precondition."); size_t len = 0; HeapRegion* cur = _free_region_list; while (cur != NULL) { len++; cur = cur->next_from_free_list(); } return len; } size_t G1CollectedHeap::unclean_region_list_length() { assert(ZF_mon->owned_by_self(), "precondition."); return _unclean_region_list.length(); } size_t G1CollectedHeap::n_regions() { return _hrs->length(); } size_t G1CollectedHeap::max_regions() { return (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) / HeapRegion::GrainBytes; } size_t G1CollectedHeap::free_regions() { /* Possibly-expensive assert. assert(_free_regions == count_free_regions(), "_free_regions is off."); */ return _free_regions; } bool G1CollectedHeap::should_zf() { return _free_region_list_size < (size_t) G1ConcZFMaxRegions; } class RegionCounter: public HeapRegionClosure { size_t _n; public: RegionCounter() : _n(0) {} bool doHeapRegion(HeapRegion* r) { if (r->is_empty() && !r->popular()) { assert(!r->isHumongous(), "H regions should not be empty."); _n++; } return false; } int res() { return (int) _n; } }; size_t G1CollectedHeap::count_free_regions() { RegionCounter rc; heap_region_iterate(&rc); size_t n = rc.res(); if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty()) n--; return n; } size_t G1CollectedHeap::count_free_regions_list() { size_t n = 0; size_t o = 0; ZF_mon->lock_without_safepoint_check(); HeapRegion* cur = _free_region_list; while (cur != NULL) { cur = cur->next_from_free_list(); n++; } size_t m = unclean_region_list_length(); ZF_mon->unlock(); return n + m; } bool G1CollectedHeap::should_set_young_locked() { assert(heap_lock_held_for_gc(), "the heap lock should already be held by or for this thread"); return (g1_policy()->in_young_gc_mode() && g1_policy()->should_add_next_region_to_young_list()); } 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 ignore_scan_only_list, bool check_sample) { bool ret = true; ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample); if (!ignore_scan_only_list) { 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() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); while (pop_unclean_region_list_locked() != NULL) ; assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0, "Postconditions of loop.") while (pop_free_region_list_locked() != NULL) ; assert(_free_region_list == NULL, "Postcondition of loop."); if (_free_region_list_size != 0) { gclog_or_tty->print_cr("Size is %d.", _free_region_list_size); print(); } assert(_free_region_list_size == 0, "Postconditions of loop."); } class RegionResetter: public HeapRegionClosure { G1CollectedHeap* _g1; int _n; public: RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {} 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())); } r->set_zero_fill_allocated(); } else { assert(r->is_empty(), "tautology"); if (r->popular()) { if (r->zero_fill_state() != HeapRegion::Allocated) { r->ensure_zero_filled_locked(); r->set_zero_fill_allocated(); } } else { _n++; switch (r->zero_fill_state()) { case HeapRegion::NotZeroFilled: case HeapRegion::ZeroFilling: _g1->put_region_on_unclean_list_locked(r); break; case HeapRegion::Allocated: r->set_zero_fill_complete(); // no break; go on to put on free list. case HeapRegion::ZeroFilled: _g1->put_free_region_on_list_locked(r); break; } } } return false; } int getFreeRegionCount() {return _n;} }; // Done at the end of full GC. void G1CollectedHeap::rebuild_region_lists() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); // This needs to go at the end of the full GC. RegionResetter rs; heap_region_iterate(&rs); _free_regions = rs.getFreeRegionCount(); // Tell the ZF thread it may have work to do. if (should_zf()) ZF_mon->notify_all(); } class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure { G1CollectedHeap* _g1; int _n; public: UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {} bool doHeapRegion(HeapRegion* r) { if (r->continuesHumongous()) return false; if (r->top() > r->bottom()) { // There are assertions in "set_zero_fill_needed()" below that // require top() == bottom(), so this is technically illegal. // We'll skirt the law here, by making that true temporarily. DEBUG_ONLY(HeapWord* save_top = r->top(); r->set_top(r->bottom())); r->set_zero_fill_needed(); DEBUG_ONLY(r->set_top(save_top)); } return false; } }; // Done at the start of full GC. void G1CollectedHeap::set_used_regions_to_need_zero_fill() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); // This needs to go at the end of the full GC. UsedRegionsNeedZeroFillSetter rs; heap_region_iterate(&rs); } class CountObjClosure: public ObjectClosure { size_t _n; public: CountObjClosure() : _n(0) {} void do_object(oop obj) { _n++; } size_t n() { return _n; } }; size_t G1CollectedHeap::pop_object_used_objs() { size_t sum_objs = 0; for (int i = 0; i < G1NumPopularRegions; i++) { CountObjClosure cl; _hrs->at(i)->object_iterate(&cl); sum_objs += cl.n(); } return sum_objs; } size_t G1CollectedHeap::pop_object_used_bytes() { size_t sum_bytes = 0; for (int i = 0; i < G1NumPopularRegions; i++) { sum_bytes += _hrs->at(i)->used(); } return sum_bytes; } static int nq = 0; HeapWord* G1CollectedHeap::allocate_popular_object(size_t word_size) { while (_cur_pop_hr_index < G1NumPopularRegions) { HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index); HeapWord* res = cur_pop_region->allocate(word_size); if (res != NULL) { // We account for popular objs directly in the used summary: _summary_bytes_used += (word_size * HeapWordSize); return res; } // Otherwise, try the next region (first making sure that we remember // the last "top" value as the "next_top_at_mark_start", so that // objects made popular during markings aren't automatically considered // live). cur_pop_region->note_end_of_copying(); // Otherwise, try the next region. _cur_pop_hr_index++; } // XXX: For now !!! vm_exit_out_of_memory(word_size, "Not enough pop obj space (To Be Fixed)"); return NULL; } class HeapRegionList: public CHeapObj { public: HeapRegion* hr; HeapRegionList* next; }; void G1CollectedHeap::schedule_popular_region_evac(HeapRegion* r) { // This might happen during parallel GC, so protect by this lock. MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); // We don't schedule regions whose evacuations are already pending, or // are already being evacuated. if (!r->popular_pending() && !r->in_collection_set()) { r->set_popular_pending(true); if (G1TracePopularity) { gclog_or_tty->print_cr("Scheduling region "PTR_FORMAT" " "["PTR_FORMAT", "PTR_FORMAT") for pop-object evacuation.", r, r->bottom(), r->end()); } HeapRegionList* hrl = new HeapRegionList; hrl->hr = r; hrl->next = _popular_regions_to_be_evacuated; _popular_regions_to_be_evacuated = hrl; } } HeapRegion* G1CollectedHeap::popular_region_to_evac() { MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); HeapRegion* res = NULL; while (_popular_regions_to_be_evacuated != NULL && res == NULL) { HeapRegionList* hrl = _popular_regions_to_be_evacuated; _popular_regions_to_be_evacuated = hrl->next; res = hrl->hr; // The G1RSPopLimit may have increased, so recheck here... if (res->rem_set()->occupied() < (size_t) G1RSPopLimit) { // Hah: don't need to schedule. if (G1TracePopularity) { gclog_or_tty->print_cr("Unscheduling region "PTR_FORMAT" " "["PTR_FORMAT", "PTR_FORMAT") " "for pop-object evacuation (size %d < limit %d)", res, res->bottom(), res->end(), res->rem_set()->occupied(), G1RSPopLimit); } res->set_popular_pending(false); res = NULL; } // We do not reset res->popular() here; if we did so, it would allow // the region to be "rescheduled" for popularity evacuation. Instead, // this is done in the collection pause, with the world stopped. // So the invariant is that the regions in the list have the popularity // boolean set, but having the boolean set does not imply membership // on the list (though there can at most one such pop-pending region // not on the list at any time). delete hrl; } return res; } void G1CollectedHeap::evac_popular_region(HeapRegion* hr) { while (true) { // Don't want to do a GC pause while cleanup is being completed! wait_for_cleanup_complete(); // Read the GC count while holding the Heap_lock int gc_count_before = SharedHeap::heap()->total_collections(); g1_policy()->record_stop_world_start(); { MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back VM_G1PopRegionCollectionPause op(gc_count_before, hr); VMThread::execute(&op); // If the prolog succeeded, we didn't do a GC for this. if (op.prologue_succeeded()) break; } // Otherwise we didn't. We should recheck the size, though, since // the limit may have increased... if (hr->rem_set()->occupied() < (size_t) G1RSPopLimit) { hr->set_popular_pending(false); break; } } } void G1CollectedHeap::atomic_inc_obj_rc(oop obj) { Atomic::inc(obj_rc_addr(obj)); } class CountRCClosure: public OopsInHeapRegionClosure { G1CollectedHeap* _g1h; bool _parallel; public: CountRCClosure(G1CollectedHeap* g1h) : _g1h(g1h), _parallel(ParallelGCThreads > 0) {} void do_oop(narrowOop* p) { guarantee(false, "NYI"); } void do_oop(oop* p) { oop obj = *p; assert(obj != NULL, "Precondition."); if (_parallel) { // We go sticky at the limit to avoid excess contention. // If we want to track the actual RC's further, we'll need to keep a // per-thread hash table or something for the popular objects. if (_g1h->obj_rc(obj) < G1ObjPopLimit) { _g1h->atomic_inc_obj_rc(obj); } } else { _g1h->inc_obj_rc(obj); } } }; class EvacPopObjClosure: public ObjectClosure { G1CollectedHeap* _g1h; size_t _pop_objs; size_t _max_rc; public: EvacPopObjClosure(G1CollectedHeap* g1h) : _g1h(g1h), _pop_objs(0), _max_rc(0) {} void do_object(oop obj) { size_t rc = _g1h->obj_rc(obj); _max_rc = MAX2(rc, _max_rc); if (rc >= (size_t) G1ObjPopLimit) { _g1h->_pop_obj_rc_at_copy.add((double)rc); size_t word_sz = obj->size(); HeapWord* new_pop_loc = _g1h->allocate_popular_object(word_sz); oop new_pop_obj = (oop)new_pop_loc; Copy::aligned_disjoint_words((HeapWord*)obj, new_pop_loc, word_sz); obj->forward_to(new_pop_obj); G1ScanAndBalanceClosure scan_and_balance(_g1h); new_pop_obj->oop_iterate_backwards(&scan_and_balance); // preserve "next" mark bit if marking is in progress. if (_g1h->mark_in_progress() && !_g1h->is_obj_ill(obj)) { _g1h->concurrent_mark()->markAndGrayObjectIfNecessary(new_pop_obj); } if (G1TracePopularity) { gclog_or_tty->print_cr("Found obj " PTR_FORMAT " of word size " SIZE_FORMAT " pop (%d), move to " PTR_FORMAT, (void*) obj, word_sz, _g1h->obj_rc(obj), (void*) new_pop_obj); } _pop_objs++; } } size_t pop_objs() { return _pop_objs; } size_t max_rc() { return _max_rc; } }; class G1ParCountRCTask : public AbstractGangTask { G1CollectedHeap* _g1h; BitMap _bm; size_t getNCards() { return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1) / G1BlockOffsetSharedArray::N_bytes; } CountRCClosure _count_rc_closure; public: G1ParCountRCTask(G1CollectedHeap* g1h) : AbstractGangTask("G1 Par RC Count task"), _g1h(g1h), _bm(getNCards()), _count_rc_closure(g1h) {} void work(int i) { ResourceMark rm; HandleMark hm; _g1h->g1_rem_set()->oops_into_collection_set_do(&_count_rc_closure, i); } }; void G1CollectedHeap::popularity_pause_preamble(HeapRegion* popular_region) { // We're evacuating a single region (for popularity). if (G1TracePopularity) { gclog_or_tty->print_cr("Doing pop region pause for ["PTR_FORMAT", "PTR_FORMAT")", popular_region->bottom(), popular_region->end()); } g1_policy()->set_single_region_collection_set(popular_region); size_t max_rc; if (!compute_reference_counts_and_evac_popular(popular_region, &max_rc)) { // We didn't evacuate any popular objects. // We increase the RS popularity limit, to prevent this from // happening in the future. if (G1RSPopLimit < (1 << 30)) { G1RSPopLimit *= 2; } // For now, interesting enough for a message: #if 1 gclog_or_tty->print_cr("In pop region pause for ["PTR_FORMAT", "PTR_FORMAT"), " "failed to find a pop object (max = %d).", popular_region->bottom(), popular_region->end(), max_rc); gclog_or_tty->print_cr("Increased G1RSPopLimit to %d.", G1RSPopLimit); #endif // 0 // Also, we reset the collection set to NULL, to make the rest of // the collection do nothing. assert(popular_region->next_in_collection_set() == NULL, "should be single-region."); popular_region->set_in_collection_set(false); popular_region->set_popular_pending(false); g1_policy()->clear_collection_set(); } } bool G1CollectedHeap:: compute_reference_counts_and_evac_popular(HeapRegion* popular_region, size_t* max_rc) { HeapWord* rc_region_bot; HeapWord* rc_region_end; // Set up the reference count region. HeapRegion* rc_region = newAllocRegion(HeapRegion::GrainWords); if (rc_region != NULL) { rc_region_bot = rc_region->bottom(); rc_region_end = rc_region->end(); } else { rc_region_bot = NEW_C_HEAP_ARRAY(HeapWord, HeapRegion::GrainWords); if (rc_region_bot == NULL) { vm_exit_out_of_memory(HeapRegion::GrainWords, "No space for RC region."); } rc_region_end = rc_region_bot + HeapRegion::GrainWords; } if (G1TracePopularity) gclog_or_tty->print_cr("RC region is ["PTR_FORMAT", "PTR_FORMAT")", rc_region_bot, rc_region_end); if (rc_region_bot > popular_region->bottom()) { _rc_region_above = true; _rc_region_diff = pointer_delta(rc_region_bot, popular_region->bottom(), 1); } else { assert(rc_region_bot < popular_region->bottom(), "Can't be equal."); _rc_region_above = false; _rc_region_diff = pointer_delta(popular_region->bottom(), rc_region_bot, 1); } g1_policy()->record_pop_compute_rc_start(); // Count external references. g1_rem_set()->prepare_for_oops_into_collection_set_do(); if (ParallelGCThreads > 0) { set_par_threads(workers()->total_workers()); G1ParCountRCTask par_count_rc_task(this); workers()->run_task(&par_count_rc_task); set_par_threads(0); } else { CountRCClosure count_rc_closure(this); g1_rem_set()->oops_into_collection_set_do(&count_rc_closure, 0); } g1_rem_set()->cleanup_after_oops_into_collection_set_do(); g1_policy()->record_pop_compute_rc_end(); // Now evacuate popular objects. g1_policy()->record_pop_evac_start(); EvacPopObjClosure evac_pop_obj_cl(this); popular_region->object_iterate(&evac_pop_obj_cl); *max_rc = evac_pop_obj_cl.max_rc(); // Make sure the last "top" value of the current popular region is copied // as the "next_top_at_mark_start", so that objects made popular during // markings aren't automatically considered live. HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index); cur_pop_region->note_end_of_copying(); if (rc_region != NULL) { free_region(rc_region); } else { FREE_C_HEAP_ARRAY(HeapWord, rc_region_bot); } g1_policy()->record_pop_evac_end(); return evac_pop_obj_cl.pop_objs() > 0; } class CountPopObjInfoClosure: public HeapRegionClosure { size_t _objs; size_t _bytes; class CountObjClosure: public ObjectClosure { int _n; public: CountObjClosure() : _n(0) {} void do_object(oop obj) { _n++; } size_t n() { return _n; } }; public: CountPopObjInfoClosure() : _objs(0), _bytes(0) {} bool doHeapRegion(HeapRegion* r) { _bytes += r->used(); CountObjClosure blk; r->object_iterate(&blk); _objs += blk.n(); return false; } size_t objs() { return _objs; } size_t bytes() { return _bytes; } }; void G1CollectedHeap::print_popularity_summary_info() const { CountPopObjInfoClosure blk; for (int i = 0; i <= _cur_pop_hr_index; i++) { blk.doHeapRegion(_hrs->at(i)); } gclog_or_tty->print_cr("\nPopular objects: %d objs, %d bytes.", blk.objs(), blk.bytes()); gclog_or_tty->print_cr(" RC at copy = [avg = %5.2f, max = %5.2f, sd = %5.2f].", _pop_obj_rc_at_copy.avg(), _pop_obj_rc_at_copy.maximum(), _pop_obj_rc_at_copy.sd()); } void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { _refine_cte_cl->set_concurrent(concurrent); } #ifndef PRODUCT class PrintHeapRegionClosure: public HeapRegionClosure { public: bool doHeapRegion(HeapRegion *r) { gclog_or_tty->print("Region: "PTR_FORMAT":", r); if (r != NULL) { if (r->is_on_free_list()) gclog_or_tty->print("Free "); if (r->is_young()) gclog_or_tty->print("Young "); if (r->isHumongous()) gclog_or_tty->print("Is Humongous "); r->print(); } return false; } }; class SortHeapRegionClosure : public HeapRegionClosure { size_t young_regions,free_regions, unclean_regions; size_t hum_regions, count; size_t unaccounted, cur_unclean, cur_alloc; size_t total_free; HeapRegion* cur; public: SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0), free_regions(0), unclean_regions(0), hum_regions(0), count(0), unaccounted(0), cur_alloc(0), total_free(0) {} bool doHeapRegion(HeapRegion *r) { count++; if (r->is_on_free_list()) free_regions++; else if (r->is_on_unclean_list()) unclean_regions++; else if (r->isHumongous()) hum_regions++; else if (r->is_young()) young_regions++; else if (r == cur) cur_alloc++; else unaccounted++; return false; } void print() { total_free = free_regions + unclean_regions; gclog_or_tty->print("%d regions\n", count); gclog_or_tty->print("%d free: free_list = %d unclean = %d\n", total_free, free_regions, unclean_regions); gclog_or_tty->print("%d humongous %d young\n", hum_regions, young_regions); gclog_or_tty->print("%d cur_alloc\n", cur_alloc); gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted); } }; void G1CollectedHeap::print_region_counts() { SortHeapRegionClosure sc(_cur_alloc_region); PrintHeapRegionClosure cl; heap_region_iterate(&cl); heap_region_iterate(&sc); sc.print(); print_region_accounting_info(); }; bool G1CollectedHeap::regions_accounted_for() { // TODO: regions accounting for young/survivor/tenured return true; } bool G1CollectedHeap::print_region_accounting_info() { gclog_or_tty->print_cr("P regions: %d.", G1NumPopularRegions); gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).", free_regions(), count_free_regions(), count_free_regions_list(), _free_region_list_size, _unclean_region_list.sz()); gclog_or_tty->print_cr("cur_alloc: %d.", (_cur_alloc_region == NULL ? 0 : 1)); gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions); // TODO: check regions accounting for young/survivor/tenured return true; } 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); } } #endif // PRODUCT void G1CollectedHeap::g1_unimplemented() { // Unimplemented(); } // Local Variables: *** // c-indentation-style: gnu *** // End: ***