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/javaClasses.hpp"
27 #include "classfile/protectionDomainCache.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "gc/shared/oopStorage.hpp"
32 #include "gc/shared/oopStorageSet.hpp"
33 #include "memory/universe.hpp"
34 #include "runtime/handles.inline.hpp"
35 #include "runtime/interfaceSupport.inline.hpp"
36 #include "runtime/javaCalls.hpp"
37 #include "runtime/jniHandles.hpp"
38 #include "runtime/serviceThread.hpp"
39 #include "runtime/mutexLocker.hpp"
40 #include "runtime/os.hpp"
41 #include "prims/jvmtiImpl.hpp"
42 #include "prims/resolvedMethodTable.hpp"
43 #include "services/diagnosticArgument.hpp"
44 #include "services/diagnosticFramework.hpp"
45 #include "services/gcNotifier.hpp"
46 #include "services/lowMemoryDetector.hpp"
47 #include "services/threadIdTable.hpp"
48
49 ServiceThread* ServiceThread::_instance = NULL;
50 JvmtiDeferredEvent* ServiceThread::_jvmti_event = NULL;
51 // The service thread has it's own static deferred event queue.
52 // Events can be posted before JVMTI vm_start, so it's too early to call JvmtiThreadState::state_for
53 // to add this field to the per-JavaThread event queue. TODO: fix this sometime later
54 JvmtiDeferredEventQueue ServiceThread::_jvmti_service_queue;
55
56 void ServiceThread::initialize() {
57 EXCEPTION_MARK;
58
59 const char* name = "Service Thread";
60 Handle string = java_lang_String::create_from_str(name, CHECK);
61
62 // Initialize thread_oop to put it into the system threadGroup
63 Handle thread_group (THREAD, Universe::system_thread_group());
64 Handle thread_oop = JavaCalls::construct_new_instance(
65 SystemDictionary::Thread_klass(),
66 vmSymbols::threadgroup_string_void_signature(),
67 thread_group,
68 string,
69 CHECK);
70
71 {
72 MutexLocker mu(THREAD, Threads_lock);
73 ServiceThread* thread = new ServiceThread(&service_thread_entry);
74
75 // At this point it may be possible that no osthread was created for the
76 // JavaThread due to lack of memory. We would have to throw an exception
77 // in that case. However, since this must work and we do not allow
78 // exceptions anyway, check and abort if this fails.
79 if (thread == NULL || thread->osthread() == NULL) {
80 vm_exit_during_initialization("java.lang.OutOfMemoryError",
81 os::native_thread_creation_failed_msg());
82 }
83
84 java_lang_Thread::set_thread(thread_oop(), thread);
85 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
86 java_lang_Thread::set_daemon(thread_oop());
87 thread->set_threadObj(thread_oop());
88 _instance = thread;
89
90 Threads::add(thread);
91 Thread::start(thread);
92 }
93 }
94
95 static void cleanup_oopstorages() {
96 OopStorageSet::Iterator it = OopStorageSet::all_iterator();
97 for ( ; !it.is_end(); ++it) {
98 it->delete_empty_blocks();
99 }
100 }
101
102 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
103 while (true) {
104 bool sensors_changed = false;
105 bool has_jvmti_events = false;
106 bool has_gc_notification_event = false;
107 bool has_dcmd_notification_event = false;
108 bool stringtable_work = false;
109 bool symboltable_work = false;
110 bool resolved_method_table_work = false;
111 bool thread_id_table_work = false;
112 bool protection_domain_table_work = false;
113 bool oopstorage_work = false;
114 bool deflate_idle_monitors = false;
115 JvmtiDeferredEvent jvmti_event;
116 {
117 // Need state transition ThreadBlockInVM so that this thread
118 // will be handled by safepoint correctly when this thread is
119 // notified at a safepoint.
120
121 // This ThreadBlockInVM object is not also considered to be
122 // suspend-equivalent because ServiceThread is not visible to
123 // external suspension.
124
125 ThreadBlockInVM tbivm(jt);
126
127 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
128 // Process all available work on each (outer) iteration, rather than
129 // only the first recognized bit of work, to avoid frequently true early
130 // tests from potentially starving later work. Hence the use of
131 // arithmetic-or to combine results; we don't want short-circuiting.
132 while (((sensors_changed = (!UseNotificationThread && LowMemoryDetector::has_pending_requests())) |
133 (has_jvmti_events = _jvmti_service_queue.has_events()) |
134 (has_gc_notification_event = (!UseNotificationThread && GCNotifier::has_event())) |
135 (has_dcmd_notification_event = (!UseNotificationThread && DCmdFactory::has_pending_jmx_notification())) |
136 (stringtable_work = StringTable::has_work()) |
137 (symboltable_work = SymbolTable::has_work()) |
138 (resolved_method_table_work = ResolvedMethodTable::has_work()) |
139 (thread_id_table_work = ThreadIdTable::has_work()) |
140 (protection_domain_table_work = SystemDictionary::pd_cache_table()->has_work()) |
141 (oopstorage_work = OopStorage::has_cleanup_work_and_reset()) |
142 (deflate_idle_monitors = ObjectSynchronizer::is_async_deflation_needed())
143 ) == 0) {
144 // Wait until notified that there is some work to do.
145 // If AsyncDeflateIdleMonitors, then we wait for
146 // GuaranteedSafepointInterval so that is_async_deflation_needed()
147 // is checked at the same interval.
148 ml.wait(AsyncDeflateIdleMonitors ? GuaranteedSafepointInterval : 0);
149 }
150
151 if (has_jvmti_events) {
152 // Get the event under the Service_lock
153 jvmti_event = _jvmti_service_queue.dequeue();
154 _jvmti_event = &jvmti_event;
155 }
156 }
157
158 if (stringtable_work) {
159 StringTable::do_concurrent_work(jt);
160 }
161
162 if (symboltable_work) {
163 SymbolTable::do_concurrent_work(jt);
164 }
165
166 if (has_jvmti_events) {
167 _jvmti_event->post();
168 _jvmti_event = NULL; // reset
169 }
170
171 if (!UseNotificationThread) {
172 if (sensors_changed) {
173 LowMemoryDetector::process_sensor_changes(jt);
174 }
175
176 if(has_gc_notification_event) {
177 GCNotifier::sendNotification(CHECK);
178 }
179
180 if(has_dcmd_notification_event) {
181 DCmdFactory::send_notification(CHECK);
182 }
183 }
184
185 if (resolved_method_table_work) {
186 ResolvedMethodTable::do_concurrent_work(jt);
187 }
188
189 if (thread_id_table_work) {
190 ThreadIdTable::do_concurrent_work(jt);
191 }
192
193 if (protection_domain_table_work) {
194 SystemDictionary::pd_cache_table()->unlink();
195 }
196
197 if (oopstorage_work) {
198 cleanup_oopstorages();
199 }
200
201 if (deflate_idle_monitors) {
202 ObjectSynchronizer::deflate_idle_monitors_using_JT();
203 }
204 }
205 }
206
207 void ServiceThread::enqueue_deferred_event(JvmtiDeferredEvent* event) {
208 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
209 // If you enqueue events before the service thread runs, gc and the sweeper
210 // cannot keep the nmethod alive. This could be restricted to compiled method
211 // load and unload events, if we wanted to be picky.
212 assert(_instance != NULL, "cannot enqueue events before the service thread runs");
213 _jvmti_service_queue.enqueue(*event);
214 Service_lock->notify_all();
215 }
216
217 void ServiceThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
218 JavaThread::oops_do(f, cf);
219 // The ServiceThread "owns" the JVMTI Deferred events, scan them here
220 // to keep them alive until they are processed.
221 if (cf != NULL) {
222 if (_jvmti_event != NULL) {
223 _jvmti_event->oops_do(f, cf);
224 }
225 // Requires a lock, because threads can be adding to this queue.
226 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
227 _jvmti_service_queue.oops_do(f, cf);
228 }
229 }
230
231 void ServiceThread::nmethods_do(CodeBlobClosure* cf) {
232 JavaThread::nmethods_do(cf);
233 if (cf != NULL) {
234 if (_jvmti_event != NULL) {
235 _jvmti_event->nmethods_do(cf);
236 }
237 // Requires a lock, because threads can be adding to this queue.
238 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
239 _jvmti_service_queue.nmethods_do(cf);
240 }
241 }