--- /dev/null 2014-01-08 17:25:58.840516250 +0100 +++ new/src/share/vm/gc_implementation/g1/g1StringDedup.cpp 2014-03-18 13:37:22.617589280 +0100 @@ -0,0 +1,208 @@ +/* + * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#include "precompiled.hpp" +#include "classfile/javaClasses.hpp" +#include "gc_implementation/g1/g1CollectedHeap.inline.hpp" +#include "gc_implementation/g1/g1GCPhaseTimes.hpp" +#include "gc_implementation/g1/g1StringDedup.hpp" +#include "gc_implementation/g1/g1StringDedupQueue.hpp" +#include "gc_implementation/g1/g1StringDedupStat.hpp" +#include "gc_implementation/g1/g1StringDedupTable.hpp" +#include "gc_implementation/g1/g1StringDedupThread.hpp" + +bool G1StringDedup::_enabled = false; + +void G1StringDedup::initialize() { + assert(UseG1GC, "String deduplication only available with G1"); + if (UseStringDeduplication) { + _enabled = true; + G1StringDedupQueue::create(); + G1StringDedupTable::create(); + G1StringDedupThread::create(); + } +} + +bool G1StringDedup::is_candidate_from_mark(oop obj) { + if (java_lang_String::is_instance(obj)) { + bool from_young = G1CollectedHeap::heap()->heap_region_containing_raw(obj)->is_young(); + if (from_young && obj->age() < StringDeduplicationAgeThreshold) { + // Candidate found. String is being evacuated from young to old but has not + // reached the deduplication age threshold, i.e. has not previously been a + // candidate during its life in the young generation. + return true; + } + } + + // Not a candidate + return false; +} + +void G1StringDedup::enqueue_from_mark(oop java_string) { + assert(is_enabled(), "String deduplication not enabled"); + if (is_candidate_from_mark(java_string)) { + G1StringDedupQueue::push(0 /* worker_id */, java_string); + } +} + +bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) { + if (from_young && java_lang_String::is_instance(obj)) { + if (to_young && obj->age() == StringDeduplicationAgeThreshold) { + // Candidate found. String is being evacuated from young to young and just + // reached the deduplication age threshold. + return true; + } + if (!to_young && obj->age() < StringDeduplicationAgeThreshold) { + // Candidate found. String is being evacuated from young to old but has not + // reached the deduplication age threshold, i.e. has not previously been a + // candidate during its life in the young generation. + return true; + } + } + + // Not a candidate + return false; +} + +void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) { + assert(is_enabled(), "String deduplication not enabled"); + if (is_candidate_from_evacuation(from_young, to_young, java_string)) { + G1StringDedupQueue::push(worker_id, java_string); + } +} + +void G1StringDedup::deduplicate(oop java_string) { + assert(is_enabled(), "String deduplication not enabled"); + G1StringDedupStat dummy; // Statistics from this path is never used + G1StringDedupTable::deduplicate(java_string, dummy); +} + +void G1StringDedup::oops_do(OopClosure* keep_alive) { + assert(is_enabled(), "String deduplication not enabled"); + unlink_or_oops_do(NULL, keep_alive); +} + +void G1StringDedup::unlink(BoolObjectClosure* is_alive) { + assert(is_enabled(), "String deduplication not enabled"); + // Don't allow a potential resize or rehash during unlink, as the unlink + // operation itself might remove enough entries to invalidate such a decision. + unlink_or_oops_do(is_alive, NULL, false /* allow_resize_and_rehash */); +} + +// +// Task for parallel unlink_or_oops_do() operation on the deduplication queue +// and table. +// +class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask { +private: + G1StringDedupUnlinkOrOopsDoClosure _cl; + +public: + G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive, + OopClosure* keep_alive, + bool allow_resize_and_rehash) : + AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"), + _cl(is_alive, keep_alive, allow_resize_and_rehash) { + } + + virtual void work(uint worker_id) { + double queue_fixup_start = os::elapsedTime(); + G1StringDedupQueue::unlink_or_oops_do(&_cl); + + double table_fixup_start = os::elapsedTime(); + G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id); + + double queue_fixup_time_ms = (table_fixup_start - queue_fixup_start) * 1000.0; + double table_fixup_time_ms = (os::elapsedTime() - table_fixup_start) * 1000.0; + G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); + g1p->phase_times()->record_string_dedup_queue_fixup_worker_time(worker_id, queue_fixup_time_ms); + g1p->phase_times()->record_string_dedup_table_fixup_worker_time(worker_id, table_fixup_time_ms); + } +}; + +void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) { + assert(is_enabled(), "String deduplication not enabled"); + G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); + g1p->phase_times()->note_string_dedup_fixup_start(); + double fixup_start = os::elapsedTime(); + + G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash); + if (G1CollectedHeap::use_parallel_gc_threads()) { + G1CollectedHeap* g1h = G1CollectedHeap::heap(); + g1h->set_par_threads(); + g1h->workers()->run_task(&task); + g1h->set_par_threads(0); + } else { + task.work(0); + } + + double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; + g1p->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); + g1p->phase_times()->note_string_dedup_fixup_end(); +} + +void G1StringDedup::threads_do(ThreadClosure* tc) { + assert(is_enabled(), "String deduplication not enabled"); + tc->do_thread(G1StringDedupThread::thread()); +} + +void G1StringDedup::print_worker_threads_on(outputStream* st) { + assert(is_enabled(), "String deduplication not enabled"); + G1StringDedupThread::thread()->print_on(st); + st->cr(); +} + +void G1StringDedup::verify() { + assert(is_enabled(), "String deduplication not enabled"); + G1StringDedupQueue::verify(); + G1StringDedupTable::verify(); +} + +G1StringDedupUnlinkOrOopsDoClosure::G1StringDedupUnlinkOrOopsDoClosure(BoolObjectClosure* is_alive, + OopClosure* keep_alive, + bool allow_resize_and_rehash) : + _is_alive(is_alive), + _keep_alive(keep_alive), + _resized_table(NULL), + _rehashed_table(NULL), + _next_queue(0), + _next_bucket(0) { + if (allow_resize_and_rehash) { + // If both resize and rehash is needed, only do resize. Rehash of + // the table will eventually happen if the situation persists. + _resized_table = G1StringDedupTable::prepare_resize(); + if (!is_resizing()) { + _rehashed_table = G1StringDedupTable::prepare_rehash(); + } + } +} + +G1StringDedupUnlinkOrOopsDoClosure::~G1StringDedupUnlinkOrOopsDoClosure() { + assert(!is_resizing() || !is_rehashing(), "Can not both resize and rehash"); + if (is_resizing()) { + G1StringDedupTable::finish_resize(_resized_table); + } else if (is_rehashing()) { + G1StringDedupTable::finish_rehash(_rehashed_table); + } +}