1 /*
2 * Copyright (c) 2012, 2017, 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 */
24
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 "runtime/os.hpp"
31 #include "prims/jvmtiImpl.hpp"
32 #include "services/allocationContextService.hpp"
33 #include "services/diagnosticArgument.hpp"
34 #include "services/diagnosticFramework.hpp"
35 #include "services/gcNotifier.hpp"
36 #include "services/lowMemoryDetector.hpp"
37
38 ServiceThread* ServiceThread::_instance = NULL;
39
40 void ServiceThread::initialize() {
41 EXCEPTION_MARK;
42
43 InstanceKlass* klass = SystemDictionary::Thread_klass();
44 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
45
46 const char* name = "Service Thread";
47
48 Handle string = java_lang_String::create_from_str(name, CHECK);
49
50 // Initialize thread_oop to put it into the system threadGroup
51 Handle thread_group (THREAD, Universe::system_thread_group());
52 JavaValue result(T_VOID);
53 JavaCalls::call_special(&result, thread_oop,
54 klass,
55 vmSymbols::object_initializer_name(),
56 vmSymbols::threadgroup_string_void_signature(),
57 thread_group,
58 string,
59 CHECK);
60
61 {
62 MutexLocker mu(Threads_lock);
63 ServiceThread* thread = new ServiceThread(&service_thread_entry);
64
65 // At this point it may be possible that no osthread was created for the
66 // JavaThread due to lack of memory. We would have to throw an exception
67 // in that case. However, since this must work and we do not allow
68 // exceptions anyway, check and abort if this fails.
69 if (thread == NULL || thread->osthread() == NULL) {
70 vm_exit_during_initialization("java.lang.OutOfMemoryError",
71 os::native_thread_creation_failed_msg());
72 }
73
74 java_lang_Thread::set_thread(thread_oop(), thread);
75 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
76 java_lang_Thread::set_daemon(thread_oop());
77 thread->set_threadObj(thread_oop());
78 _instance = thread;
79
80 Threads::add(thread);
81 Thread::start(thread);
82 }
83 }
84
85 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
86 while (true) {
87 bool sensors_changed = false;
88 bool has_jvmti_events = false;
89 bool has_gc_notification_event = false;
90 bool has_dcmd_notification_event = false;
91 bool acs_notify = false;
92 bool deflate_idle_monitors = false;
93 JvmtiDeferredEvent jvmti_event;
94 {
95 // Need state transition ThreadBlockInVM so that this thread
96 // will be handled by safepoint correctly when this thread is
97 // notified at a safepoint.
98
99 // This ThreadBlockInVM object is not also considered to be
100 // suspend-equivalent because ServiceThread is not visible to
101 // external suspension.
102
103 ThreadBlockInVM tbivm(jt);
104
105 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
106 while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
107 !(has_jvmti_events = JvmtiDeferredEventQueue::has_events()) &&
108 !(has_gc_notification_event = GCNotifier::has_event()) &&
109 !(has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) &&
110 !(acs_notify = AllocationContextService::should_notify()) &&
111 !(deflate_idle_monitors = ObjectSynchronizer::should_deflate_idle_monitors_conc())) {
112 // wait until one of the sensors has pending requests, or there is a
113 // pending JVMTI event or JMX GC notification to post
114 Service_lock->wait(Mutex::_no_safepoint_check_flag);
115 }
116
117 if (has_jvmti_events) {
118 jvmti_event = JvmtiDeferredEventQueue::dequeue();
119 }
120 }
121
122 if (has_jvmti_events) {
123 jvmti_event.post();
124 }
125
126 if (sensors_changed) {
127 LowMemoryDetector::process_sensor_changes(jt);
128 }
129
130 if(has_gc_notification_event) {
131 GCNotifier::sendNotification(CHECK);
132 }
133
134 if(has_dcmd_notification_event) {
135 DCmdFactory::send_notification(CHECK);
136 }
137
138 if (acs_notify) {
139 AllocationContextService::notify(CHECK);
140 }
141
142 if (deflate_idle_monitors) {
143 ObjectSynchronizer::deflate_idle_monitors_conc();
144 }
145 }
146 }
147
148 bool ServiceThread::is_service_thread(Thread* thread) {
149 return thread == _instance;
150 }