--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/parallelCleaning.cpp Fri Aug 24 15:49:21 2018 -0400
@@ -0,0 +1,282 @@
+/*
+ * Copyright (c) 2018, 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/symbolTable.hpp"
+#include "classfile/stringTable.hpp"
+#include "code/codeCache.hpp"
+#include "gc/shared/parallelCleaning.hpp"
+#include "memory/resourceArea.hpp"
+#include "logging/log.hpp"
+
+StringCleaningTask::StringCleaningTask(BoolObjectClosure* is_alive, StringDedupUnlinkOrOopsDoClosure* dedup_closure, bool process_strings) :
+ AbstractGangTask("String Unlinking"),
+ _is_alive(is_alive),
+ _dedup_closure(dedup_closure),
+ _par_state_string(StringTable::weak_storage()),
+ _initial_string_table_size((int) StringTable::the_table()->table_size()),
+ _process_strings(process_strings), _strings_processed(0), _strings_removed(0) {
+
+ if (process_strings) {
+ StringTable::reset_dead_counter();
+ }
+}
+
+StringCleaningTask::~StringCleaningTask() {
+ log_info(gc, stringtable)(
+ "Cleaned string table, "
+ "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
+ strings_processed(), strings_removed());
+ if (_process_strings) {
+ StringTable::finish_dead_counter();
+ }
+}
+
+void StringCleaningTask::work(uint worker_id) {
+ int strings_processed = 0;
+ int strings_removed = 0;
+ if (_process_strings) {
+ StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
+ Atomic::add(strings_processed, &_strings_processed);
+ Atomic::add(strings_removed, &_strings_removed);
+ }
+ if (_dedup_closure != NULL) {
+ StringDedup::parallel_unlink(_dedup_closure, worker_id);
+ }
+}
+
+CodeCacheUnloadingTask::CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
+ _is_alive(is_alive),
+ _unloading_occurred(unloading_occurred),
+ _num_workers(num_workers),
+ _first_nmethod(NULL),
+ _claimed_nmethod(NULL),
+ _postponed_list(NULL),
+ _num_entered_barrier(0) {
+ CompiledMethod::increase_unloading_clock();
+ // Get first alive nmethod
+ CompiledMethodIterator iter = CompiledMethodIterator();
+ if(iter.next_alive()) {
+ _first_nmethod = iter.method();
+ }
+ _claimed_nmethod = _first_nmethod;
+}
+
+CodeCacheUnloadingTask::~CodeCacheUnloadingTask() {
+ CodeCache::verify_clean_inline_caches();
+
+ CodeCache::set_needs_cache_clean(false);
+ guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
+
+ CodeCache::verify_icholder_relocations();
+}
+
+Monitor* CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
+
+void CodeCacheUnloadingTask::add_to_postponed_list(CompiledMethod* nm) {
+ CompiledMethod* old;
+ do {
+ old = _postponed_list;
+ nm->set_unloading_next(old);
+ } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
+}
+
+void CodeCacheUnloadingTask::clean_nmethod(CompiledMethod* nm) {
+ bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
+
+ if (postponed) {
+ // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
+ add_to_postponed_list(nm);
+ }
+
+ // Mark that this nmethod has been cleaned/unloaded.
+ // After this call, it will be safe to ask if this nmethod was unloaded or not.
+ nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
+}
+
+void CodeCacheUnloadingTask::clean_nmethod_postponed(CompiledMethod* nm) {
+ nm->do_unloading_parallel_postponed();
+}
+
+void CodeCacheUnloadingTask::claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
+ CompiledMethod* first;
+ CompiledMethodIterator last;
+
+ do {
+ *num_claimed_nmethods = 0;
+
+ first = _claimed_nmethod;
+ last = CompiledMethodIterator(first);
+
+ if (first != NULL) {
+
+ for (int i = 0; i < MaxClaimNmethods; i++) {
+ if (!last.next_alive()) {
+ break;
+ }
+ claimed_nmethods[i] = last.method();
+ (*num_claimed_nmethods)++;
+ }
+ }
+
+ } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
+}
+
+CompiledMethod* CodeCacheUnloadingTask::claim_postponed_nmethod() {
+ CompiledMethod* claim;
+ CompiledMethod* next;
+
+ do {
+ claim = _postponed_list;
+ if (claim == NULL) {
+ return NULL;
+ }
+
+ next = claim->unloading_next();
+
+ } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
+
+ return claim;
+}
+
+void CodeCacheUnloadingTask::barrier_mark(uint worker_id) {
+ MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+ _num_entered_barrier++;
+ if (_num_entered_barrier == _num_workers) {
+ ml.notify_all();
+ }
+}
+
+void CodeCacheUnloadingTask::barrier_wait(uint worker_id) {
+ if (_num_entered_barrier < _num_workers) {
+ MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+ while (_num_entered_barrier < _num_workers) {
+ ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
+ }
+ }
+}
+
+void CodeCacheUnloadingTask::work_first_pass(uint worker_id) {
+ // The first nmethods is claimed by the first worker.
+ if (worker_id == 0 && _first_nmethod != NULL) {
+ clean_nmethod(_first_nmethod);
+ _first_nmethod = NULL;
+ }
+
+ int num_claimed_nmethods;
+ CompiledMethod* claimed_nmethods[MaxClaimNmethods];
+
+ while (true) {
+ claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
+
+ if (num_claimed_nmethods == 0) {
+ break;
+ }
+
+ for (int i = 0; i < num_claimed_nmethods; i++) {
+ clean_nmethod(claimed_nmethods[i]);
+ }
+ }
+}
+
+void CodeCacheUnloadingTask::work_second_pass(uint worker_id) {
+ CompiledMethod* nm;
+ // Take care of postponed nmethods.
+ while ((nm = claim_postponed_nmethod()) != NULL) {
+ clean_nmethod_postponed(nm);
+ }
+}
+
+KlassCleaningTask::KlassCleaningTask() :
+ _clean_klass_tree_claimed(0),
+ _klass_iterator() {
+}
+
+bool KlassCleaningTask::claim_clean_klass_tree_task() {
+ if (_clean_klass_tree_claimed) {
+ return false;
+ }
+
+ return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
+}
+
+InstanceKlass* KlassCleaningTask::claim_next_klass() {
+ Klass* klass;
+ do {
+ klass =_klass_iterator.next_klass();
+ } while (klass != NULL && !klass->is_instance_klass());
+
+ // this can be null so don't call InstanceKlass::cast
+ return static_cast<InstanceKlass*>(klass);
+}
+
+void KlassCleaningTask::work() {
+ ResourceMark rm;
+
+ // One worker will clean the subklass/sibling klass tree.
+ if (claim_clean_klass_tree_task()) {
+ Klass::clean_subklass_tree();
+ }
+
+ // All workers will help cleaning the classes,
+ InstanceKlass* klass;
+ while ((klass = claim_next_klass()) != NULL) {
+ clean_klass(klass);
+ }
+}
+
+ParallelCleaningTask::ParallelCleaningTask(BoolObjectClosure* is_alive,
+ StringDedupUnlinkOrOopsDoClosure* dedup_closure, uint num_workers, bool unloading_occurred) :
+ AbstractGangTask("Parallel Cleaning"),
+ _unloading_occurred(unloading_occurred),
+ _string_task(is_alive, StringDedup::is_enabled() ? dedup_closure : NULL, true),
+ _code_cache_task(num_workers, is_alive, unloading_occurred),
+ _klass_cleaning_task() {
+}
+
+// The parallel work done by all worker threads.
+void ParallelCleaningTask::work(uint worker_id) {
+ // Do first pass of code cache cleaning.
+ _code_cache_task.work_first_pass(worker_id);
+
+ // Let the threads mark that the first pass is done.
+ _code_cache_task.barrier_mark(worker_id);
+
+ // Clean the Strings and Symbols.
+ _string_task.work(worker_id);
+
+ // Wait for all workers to finish the first code cache cleaning pass.
+ _code_cache_task.barrier_wait(worker_id);
+
+ // Do the second code cache cleaning work, which realize on
+ // the liveness information gathered during the first pass.
+ _code_cache_task.work_second_pass(worker_id);
+
+ // Clean all klasses that were not unloaded.
+ // The weak metadata in klass doesn't need to be
+ // processed if there was no unloading.
+ if (_unloading_occurred) {
+ _klass_cleaning_task.work();
+ }
+}