Mercurial > hg > graal-compiler
view src/share/vm/runtime/serviceThread.cpp @ 3917:eca1193ca245
4965777: GC changes to support use of discovered field for pending references
Summary: If and when the reference handler thread is able to use the discovered field to link reference objects in its pending list, so will GC. In that case, GC will scan through this field once a reference object has been placed on the pending list, but not scan that field before that stage, as the field is used by the concurrent GC thread to link discovered objects. When ReferenceHandleR thread does not use the discovered field for the purpose of linking the elements in the pending list, as would be the case in older JDKs, the JVM will fall back to the old behaviour of using the next field for that purpose.
Reviewed-by: jcoomes, mchung, stefank
author | ysr |
---|---|
date | Wed, 07 Sep 2011 13:55:42 -0700 |
parents | 78542e2b5e35 |
children | 31a4e55f8c9d |
line wrap: on
line source
/* * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "runtime/interfaceSupport.hpp" #include "runtime/javaCalls.hpp" #include "runtime/serviceThread.hpp" #include "runtime/mutexLocker.hpp" #include "prims/jvmtiImpl.hpp" #include "services/gcNotifier.hpp" ServiceThread* ServiceThread::_instance = NULL; void ServiceThread::initialize() { EXCEPTION_MARK; instanceKlassHandle klass (THREAD, SystemDictionary::Thread_klass()); instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); const char* name = JDK_Version::is_gte_jdk17x_version() ? "Service Thread" : "Low Memory Detector"; Handle string = java_lang_String::create_from_str(name, CHECK); // Initialize thread_oop to put it into the system threadGroup Handle thread_group (THREAD, Universe::system_thread_group()); JavaValue result(T_VOID); JavaCalls::call_special(&result, thread_oop, klass, vmSymbols::object_initializer_name(), vmSymbols::threadgroup_string_void_signature(), thread_group, string, CHECK); { MutexLocker mu(Threads_lock); ServiceThread* thread = new ServiceThread(&service_thread_entry); // At this point it may be possible that no osthread was created for the // JavaThread due to lack of memory. We would have to throw an exception // in that case. However, since this must work and we do not allow // exceptions anyway, check and abort if this fails. if (thread == NULL || thread->osthread() == NULL) { vm_exit_during_initialization("java.lang.OutOfMemoryError", "unable to create new native thread"); } java_lang_Thread::set_thread(thread_oop(), thread); java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); java_lang_Thread::set_daemon(thread_oop()); thread->set_threadObj(thread_oop()); _instance = thread; Threads::add(thread); Thread::start(thread); } } void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) { while (true) { bool sensors_changed = false; bool has_jvmti_events = false; bool has_gc_notification_event = false; JvmtiDeferredEvent jvmti_event; { // Need state transition ThreadBlockInVM so that this thread // will be handled by safepoint correctly when this thread is // notified at a safepoint. // This ThreadBlockInVM object is not also considered to be // suspend-equivalent because ServiceThread is not visible to // external suspension. ThreadBlockInVM tbivm(jt); MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag); while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) && !(has_jvmti_events = JvmtiDeferredEventQueue::has_events()) && !(has_gc_notification_event = GCNotifier::has_event())) { // wait until one of the sensors has pending requests, or there is a // pending JVMTI event or JMX GC notification to post Service_lock->wait(Mutex::_no_safepoint_check_flag); } if (has_jvmti_events) { jvmti_event = JvmtiDeferredEventQueue::dequeue(); } } if (has_jvmti_events) { jvmti_event.post(); } if (sensors_changed) { LowMemoryDetector::process_sensor_changes(jt); } if(has_gc_notification_event) { GCNotifier::sendNotification(CHECK); } } } bool ServiceThread::is_service_thread(Thread* thread) { return thread == _instance; }