Thu, 07 Feb 2013 16:05:48 -0500
Merge
1 /*
2 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "runtime/interfaceSupport.hpp"
27 #include "runtime/javaCalls.hpp"
28 #include "runtime/serviceThread.hpp"
29 #include "runtime/mutexLocker.hpp"
30 #include "prims/jvmtiImpl.hpp"
31 #include "services/gcNotifier.hpp"
33 ServiceThread* ServiceThread::_instance = NULL;
35 void ServiceThread::initialize() {
36 EXCEPTION_MARK;
38 instanceKlassHandle klass (THREAD, SystemDictionary::Thread_klass());
39 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
41 const char* name = JDK_Version::is_gte_jdk17x_version() ?
42 "Service Thread" : "Low Memory Detector";
44 Handle string = java_lang_String::create_from_str(name, CHECK);
46 // Initialize thread_oop to put it into the system threadGroup
47 Handle thread_group (THREAD, Universe::system_thread_group());
48 JavaValue result(T_VOID);
49 JavaCalls::call_special(&result, thread_oop,
50 klass,
51 vmSymbols::object_initializer_name(),
52 vmSymbols::threadgroup_string_void_signature(),
53 thread_group,
54 string,
55 CHECK);
57 {
58 MutexLocker mu(Threads_lock);
59 ServiceThread* thread = new ServiceThread(&service_thread_entry);
61 // At this point it may be possible that no osthread was created for the
62 // JavaThread due to lack of memory. We would have to throw an exception
63 // in that case. However, since this must work and we do not allow
64 // exceptions anyway, check and abort if this fails.
65 if (thread == NULL || thread->osthread() == NULL) {
66 vm_exit_during_initialization("java.lang.OutOfMemoryError",
67 "unable to create new native thread");
68 }
70 java_lang_Thread::set_thread(thread_oop(), thread);
71 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
72 java_lang_Thread::set_daemon(thread_oop());
73 thread->set_threadObj(thread_oop());
74 _instance = thread;
76 Threads::add(thread);
77 Thread::start(thread);
78 }
79 }
81 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
82 while (true) {
83 bool sensors_changed = false;
84 bool has_jvmti_events = false;
85 bool has_gc_notification_event = false;
86 JvmtiDeferredEvent jvmti_event;
87 {
88 // Need state transition ThreadBlockInVM so that this thread
89 // will be handled by safepoint correctly when this thread is
90 // notified at a safepoint.
92 // This ThreadBlockInVM object is not also considered to be
93 // suspend-equivalent because ServiceThread is not visible to
94 // external suspension.
96 ThreadBlockInVM tbivm(jt);
98 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
99 while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
100 !(has_jvmti_events = JvmtiDeferredEventQueue::has_events()) &&
101 !(has_gc_notification_event = GCNotifier::has_event())) {
102 // wait until one of the sensors has pending requests, or there is a
103 // pending JVMTI event or JMX GC notification to post
104 Service_lock->wait(Mutex::_no_safepoint_check_flag);
105 }
107 if (has_jvmti_events) {
108 jvmti_event = JvmtiDeferredEventQueue::dequeue();
109 }
110 }
112 if (has_jvmti_events) {
113 jvmti_event.post();
114 }
116 if (sensors_changed) {
117 LowMemoryDetector::process_sensor_changes(jt);
118 }
120 if(has_gc_notification_event) {
121 GCNotifier::sendNotification(CHECK);
122 }
123 }
124 }
126 bool ServiceThread::is_service_thread(Thread* thread) {
127 return thread == _instance;
128 }