1 /*
2 * Copyright (c) 2001, 2010, 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/systemDictionary.hpp"
27 #include "gc_implementation/shared/concurrentGCThread.hpp"
28 #include "oops/instanceRefKlass.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "runtime/init.hpp"
31 #include "runtime/interfaceSupport.hpp"
32 #include "runtime/java.hpp"
33 #include "runtime/javaCalls.hpp"
34
35 // CopyrightVersion 1.2
36
37 int ConcurrentGCThread::_CGC_flag = CGC_nil;
38
39 SuspendibleThreadSet ConcurrentGCThread::_sts;
40
41 ConcurrentGCThread::ConcurrentGCThread() :
42 _should_terminate(false), _has_terminated(false) {
43 _sts.initialize();
44 };
45
46 void ConcurrentGCThread::stopWorldAndDo(VoidClosure* op) {
47 MutexLockerEx x(Heap_lock,
48 Mutex::_no_safepoint_check_flag);
49 // warning("CGC: about to try stopping world");
50 SafepointSynchronize::begin();
51 // warning("CGC: successfully stopped world");
52 op->do_void();
53 SafepointSynchronize::end();
54 // warning("CGC: successfully restarted world");
55 }
56
57 void ConcurrentGCThread::safepoint_synchronize() {
58 _sts.suspend_all();
59 }
60
61 void ConcurrentGCThread::safepoint_desynchronize() {
62 _sts.resume_all();
63 }
64
65 void ConcurrentGCThread::create_and_start() {
66 if (os::create_thread(this, os::cgc_thread)) {
67 // XXX: need to set this to low priority
68 // unless "agressive mode" set; priority
69 // should be just less than that of VMThread.
70 os::set_priority(this, NearMaxPriority);
71 if (!_should_terminate && !DisableStartThread) {
72 os::start_thread(this);
73 }
74 }
75 }
76
77 void ConcurrentGCThread::initialize_in_thread() {
78 this->record_stack_base_and_size();
79 this->initialize_thread_local_storage();
80 this->set_active_handles(JNIHandleBlock::allocate_block());
81 // From this time Thread::current() should be working.
82 assert(this == Thread::current(), "just checking");
83 }
84
85 void ConcurrentGCThread::wait_for_universe_init() {
86 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
87 while (!is_init_completed() && !_should_terminate) {
88 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
89 }
90 }
91
92 void ConcurrentGCThread::terminate() {
93 // Signal that it is terminated
94 {
95 MutexLockerEx mu(Terminator_lock,
96 Mutex::_no_safepoint_check_flag);
97 _has_terminated = true;
98 Terminator_lock->notify();
99 }
100
101 // Thread destructor usually does this..
102 ThreadLocalStorage::set_thread(NULL);
103 }
104
105
106 void SuspendibleThreadSet::initialize_work() {
107 MutexLocker x(STS_init_lock);
108 if (!_initialized) {
109 _m = new Monitor(Mutex::leaf,
110 "SuspendibleThreadSetLock", true);
111 _async = 0;
112 _async_stop = false;
113 _async_stopped = 0;
114 _initialized = true;
115 }
116 }
117
118 void SuspendibleThreadSet::join() {
119 initialize();
120 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
121 while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
122 _async++;
123 assert(_async > 0, "Huh.");
124 }
125
126 void SuspendibleThreadSet::leave() {
127 assert(_initialized, "Must be initialized.");
128 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
129 _async--;
130 assert(_async >= 0, "Huh.");
131 if (_async_stop) _m->notify_all();
132 }
133
134 void SuspendibleThreadSet::yield(const char* id) {
135 assert(_initialized, "Must be initialized.");
136 if (_async_stop) {
137 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
138 if (_async_stop) {
139 _async_stopped++;
140 assert(_async_stopped > 0, "Huh.");
141 if (_async_stopped == _async) {
142 if (ConcGCYieldTimeout > 0) {
143 double now = os::elapsedTime();
144 guarantee((now - _suspend_all_start) * 1000.0 <
145 (double)ConcGCYieldTimeout,
146 "Long delay; whodunit?");
147 }
148 }
149 _m->notify_all();
150 while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
151 _async_stopped--;
152 assert(_async >= 0, "Huh");
153 _m->notify_all();
154 }
155 }
156 }
157
158 void SuspendibleThreadSet::suspend_all() {
159 initialize(); // If necessary.
160 if (ConcGCYieldTimeout > 0) {
161 _suspend_all_start = os::elapsedTime();
162 }
163 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
164 assert(!_async_stop, "Only one at a time.");
165 _async_stop = true;
166 while (_async_stopped < _async) _m->wait(Mutex::_no_safepoint_check_flag);
167 }
168
169 void SuspendibleThreadSet::resume_all() {
170 assert(_initialized, "Must be initialized.");
171 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
172 assert(_async_stopped == _async, "Huh.");
173 _async_stop = false;
174 _m->notify_all();
175 }
176
177 static void _sltLoop(JavaThread* thread, TRAPS) {
178 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
179 slt->loop();
180 }
181
182 SurrogateLockerThread::SurrogateLockerThread() :
183 JavaThread(&_sltLoop),
184 _monitor(Mutex::nonleaf, "SLTMonitor"),
185 _buffer(empty)
186 {}
187
188 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
189 klassOop k =
190 SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(),
191 true, CHECK_NULL);
192 instanceKlassHandle klass (THREAD, k);
193 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
194
195 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)";
196 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
197
198 // Initialize thread_oop to put it into the system threadGroup
199 Handle thread_group (THREAD, Universe::system_thread_group());
200 JavaValue result(T_VOID);
201 JavaCalls::call_special(&result, thread_oop,
202 klass,
203 vmSymbolHandles::object_initializer_name(),
204 vmSymbolHandles::threadgroup_string_void_signature(),
205 thread_group,
206 string,
207 CHECK_NULL);
208
209 SurrogateLockerThread* res;
210 {
211 MutexLocker mu(Threads_lock);
212 res = new SurrogateLockerThread();
213
214 // At this point it may be possible that no osthread was created for the
215 // JavaThread due to lack of memory. We would have to throw an exception
216 // in that case. However, since this must work and we do not allow
217 // exceptions anyway, check and abort if this fails.
218 if (res == NULL || res->osthread() == NULL) {
219 vm_exit_during_initialization("java.lang.OutOfMemoryError",
220 "unable to create new native thread");
221 }
222 java_lang_Thread::set_thread(thread_oop(), res);
223 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
224 java_lang_Thread::set_daemon(thread_oop());
225
226 res->set_threadObj(thread_oop());
227 Threads::add(res);
228 Thread::start(res);
229 }
230 os::yield(); // This seems to help with initial start-up of SLT
231 return res;
232 }
233
234 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
235 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
236 assert(_buffer == empty, "Should be empty");
237 assert(msg != empty, "empty message");
238 _buffer = msg;
239 while (_buffer != empty) {
240 _monitor.notify();
241 _monitor.wait(Mutex::_no_safepoint_check_flag);
242 }
243 }
244
245 // ======= Surrogate Locker Thread =============
246
247 void SurrogateLockerThread::loop() {
248 BasicLock pll_basic_lock;
249 SLT_msg_type msg;
250 debug_only(unsigned int owned = 0;)
251
252 while (/* !isTerminated() */ 1) {
253 {
254 MutexLocker x(&_monitor);
255 // Since we are a JavaThread, we can't be here at a safepoint.
256 assert(!SafepointSynchronize::is_at_safepoint(),
257 "SLT is a JavaThread");
258 // wait for msg buffer to become non-empty
259 while (_buffer == empty) {
260 _monitor.notify();
261 _monitor.wait();
262 }
263 msg = _buffer;
264 }
265 switch(msg) {
266 case acquirePLL: {
267 instanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
268 debug_only(owned++;)
269 break;
270 }
271 case releaseAndNotifyPLL: {
272 assert(owned > 0, "Don't have PLL");
273 instanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
274 debug_only(owned--;)
275 break;
276 }
277 case empty:
278 default: {
279 guarantee(false,"Unexpected message in _buffer");
280 break;
281 }
282 }
283 {
284 MutexLocker x(&_monitor);
285 // Since we are a JavaThread, we can't be here at a safepoint.
286 assert(!SafepointSynchronize::is_at_safepoint(),
287 "SLT is a JavaThread");
288 _buffer = empty;
289 _monitor.notify();
290 }
291 }
292 assert(!_monitor.owned_by_self(), "Should unlock before exit.");
293 }
294
295
296 // ===== STS Access From Outside CGCT =====
297
298 void ConcurrentGCThread::stsYield(const char* id) {
299 assert( Thread::current()->is_ConcurrentGC_thread(),
300 "only a conc GC thread can call this" );
301 _sts.yield(id);
302 }
303
304 bool ConcurrentGCThread::stsShouldYield() {
305 assert( Thread::current()->is_ConcurrentGC_thread(),
306 "only a conc GC thread can call this" );
307 return _sts.should_yield();
308 }
309
310 void ConcurrentGCThread::stsJoin() {
311 assert( Thread::current()->is_ConcurrentGC_thread(),
312 "only a conc GC thread can call this" );
313 _sts.join();
314 }
315
316 void ConcurrentGCThread::stsLeave() {
317 assert( Thread::current()->is_ConcurrentGC_thread(),
318 "only a conc GC thread can call this" );
319 _sts.leave();
320 }