1 /*
2 * Copyright (c) 2012, 2020, 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 "classfile/protectionDomainCache.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "gc/shared/oopStorage.hpp"
31 #include "gc/shared/oopStorageSet.hpp"
32 #include "memory/universe.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/interfaceSupport.inline.hpp"
35 #include "runtime/javaCalls.hpp"
36 #include "runtime/jniHandles.hpp"
37 #include "runtime/serviceThread.hpp"
38 #include "runtime/mutexLocker.hpp"
39 #include "runtime/os.hpp"
40 #include "prims/jvmtiImpl.hpp"
41 #include "prims/resolvedMethodTable.hpp"
42 #include "services/diagnosticArgument.hpp"
43 #include "services/diagnosticFramework.hpp"
44 #include "services/gcNotifier.hpp"
45 #include "services/lowMemoryDetector.hpp"
46 #include "services/threadIdTable.hpp"
47
48 ServiceThread* ServiceThread::_instance = NULL;
49 JvmtiDeferredEvent* ServiceThread::_jvmti_event = NULL;
50 // The service thread has it's own static deferred event queue.
51 // Events can be posted before JVMTI vm_start, so it's too early to call JvmtiThreadState::state_for
52 // to add this field to the per-JavaThread event queue. TODO: fix this sometime later
53 JvmtiDeferredEventQueue ServiceThread::_jvmti_service_queue;
54
55 void ServiceThread::initialize() {
56 EXCEPTION_MARK;
57
58 const char* name = "Service Thread";
59 Handle string = java_lang_String::create_from_str(name, CHECK);
60
61 // Initialize thread_oop to put it into the system threadGroup
62 Handle thread_group (THREAD, Universe::system_thread_group());
63 Handle thread_oop = JavaCalls::construct_new_instance(
64 SystemDictionary::Thread_klass(),
65 vmSymbols::threadgroup_string_void_signature(),
66 thread_group,
67 string,
68 CHECK);
69
70 {
71 MutexLocker mu(THREAD, Threads_lock);
72 ServiceThread* thread = new ServiceThread(&service_thread_entry);
73
74 // At this point it may be possible that no osthread was created for the
75 // JavaThread due to lack of memory. We would have to throw an exception
76 // in that case. However, since this must work and we do not allow
77 // exceptions anyway, check and abort if this fails.
78 if (thread == NULL || thread->osthread() == NULL) {
79 vm_exit_during_initialization("java.lang.OutOfMemoryError",
80 os::native_thread_creation_failed_msg());
81 }
82
83 java_lang_Thread::set_thread(thread_oop(), thread);
84 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
85 java_lang_Thread::set_daemon(thread_oop());
86 thread->set_threadObj(thread_oop());
87 _instance = thread;
88
89 Threads::add(thread);
90 Thread::start(thread);
91 }
92 }
93
94 static void cleanup_oopstorages() {
95 OopStorageSet::Iterator it = OopStorageSet::all_iterator();
96 for ( ; !it.is_end(); ++it) {
97 it->delete_empty_blocks();
98 }
99 }
100
101 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
102 while (true) {
103 bool sensors_changed = false;
104 bool has_jvmti_events = false;
105 bool has_gc_notification_event = false;
106 bool has_dcmd_notification_event = false;
107 bool stringtable_work = false;
108 bool symboltable_work = false;
109 bool resolved_method_table_work = false;
110 bool thread_id_table_work = false;
111 bool protection_domain_table_work = false;
112 bool oopstorage_work = false;
113 bool deflate_idle_monitors = false;
114 JvmtiDeferredEvent jvmti_event;
115 {
116 // Need state transition ThreadBlockInVM so that this thread
117 // will be handled by safepoint correctly when this thread is
118 // notified at a safepoint.
119
120 // This ThreadBlockInVM object is not also considered to be
121 // suspend-equivalent because ServiceThread is not visible to
122 // external suspension.
123
124 ThreadBlockInVM tbivm(jt);
125
126 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
127 // Process all available work on each (outer) iteration, rather than
128 // only the first recognized bit of work, to avoid frequently true early
129 // tests from potentially starving later work. Hence the use of
130 // arithmetic-or to combine results; we don't want short-circuiting.
131 while (((sensors_changed = (!UseNotificationThread && LowMemoryDetector::has_pending_requests())) |
132 (has_jvmti_events = _jvmti_service_queue.has_events()) |
133 (has_gc_notification_event = (!UseNotificationThread && GCNotifier::has_event())) |
134 (has_dcmd_notification_event = (!UseNotificationThread && DCmdFactory::has_pending_jmx_notification())) |
135 (stringtable_work = StringTable::has_work()) |
136 (symboltable_work = SymbolTable::has_work()) |
137 (resolved_method_table_work = ResolvedMethodTable::has_work()) |
138 (thread_id_table_work = ThreadIdTable::has_work()) |
139 (protection_domain_table_work = SystemDictionary::pd_cache_table()->has_work()) |
140 (oopstorage_work = OopStorage::has_cleanup_work_and_reset()) |
141 (deflate_idle_monitors = ObjectSynchronizer::is_async_deflation_needed())
142 ) == 0) {
143 // Wait until notified that there is some work to do.
144 // We wait for GuaranteedSafepointInterval so that
145 // is_async_deflation_needed() is checked at the same interval.
146 ml.wait(GuaranteedSafepointInterval);
147 }
148
149 if (has_jvmti_events) {
150 // Get the event under the Service_lock
151 jvmti_event = _jvmti_service_queue.dequeue();
152 _jvmti_event = &jvmti_event;
153 }
154 }
155
156 if (stringtable_work) {
157 StringTable::do_concurrent_work(jt);
158 }
159
160 if (symboltable_work) {
161 SymbolTable::do_concurrent_work(jt);
162 }
163
164 if (has_jvmti_events) {
165 _jvmti_event->post();
166 _jvmti_event = NULL; // reset
167 }
168
169 if (!UseNotificationThread) {
170 if (sensors_changed) {
171 LowMemoryDetector::process_sensor_changes(jt);
172 }
173
174 if(has_gc_notification_event) {
175 GCNotifier::sendNotification(CHECK);
176 }
177
178 if(has_dcmd_notification_event) {
179 DCmdFactory::send_notification(CHECK);
180 }
181 }
182
183 if (resolved_method_table_work) {
184 ResolvedMethodTable::do_concurrent_work(jt);
185 }
186
187 if (thread_id_table_work) {
188 ThreadIdTable::do_concurrent_work(jt);
189 }
190
191 if (protection_domain_table_work) {
192 SystemDictionary::pd_cache_table()->unlink();
193 }
194
195 if (oopstorage_work) {
196 cleanup_oopstorages();
197 }
198
199 if (deflate_idle_monitors) {
200 ObjectSynchronizer::deflate_idle_monitors_using_JT();
201 }
202 }
203 }
204
205 void ServiceThread::enqueue_deferred_event(JvmtiDeferredEvent* event) {
206 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
207 // If you enqueue events before the service thread runs, gc and the sweeper
208 // cannot keep the nmethod alive. This could be restricted to compiled method
209 // load and unload events, if we wanted to be picky.
210 assert(_instance != NULL, "cannot enqueue events before the service thread runs");
211 _jvmti_service_queue.enqueue(*event);
212 Service_lock->notify_all();
213 }
214
215 void ServiceThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
216 JavaThread::oops_do(f, cf);
217 // The ServiceThread "owns" the JVMTI Deferred events, scan them here
218 // to keep them alive until they are processed.
219 if (cf != NULL) {
220 if (_jvmti_event != NULL) {
221 _jvmti_event->oops_do(f, cf);
222 }
223 // Requires a lock, because threads can be adding to this queue.
224 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
225 _jvmti_service_queue.oops_do(f, cf);
226 }
227 }
228
229 void ServiceThread::nmethods_do(CodeBlobClosure* cf) {
230 JavaThread::nmethods_do(cf);
231 if (cf != NULL) {
232 if (_jvmti_event != NULL) {
233 _jvmti_event->nmethods_do(cf);
234 }
235 // Requires a lock, because threads can be adding to this queue.
236 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
237 _jvmti_service_queue.nmethods_do(cf);
238 }
239 }