1 /*
2 * Copyright (c) 2001, 2015, 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/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 #include "runtime/os.hpp"
35
36 ConcurrentGCThread::ConcurrentGCThread() :
37 _should_terminate(false), _has_terminated(false) {
38 };
39
40 void ConcurrentGCThread::create_and_start() {
41 if (os::create_thread(this, os::cgc_thread)) {
42 // XXX: need to set this to low priority
43 // unless "aggressive mode" set; priority
44 // should be just less than that of VMThread.
45 os::set_priority(this, NearMaxPriority);
46 if (!_should_terminate && !DisableStartThread) {
47 os::start_thread(this);
48 }
49 }
50 }
51
52 void ConcurrentGCThread::initialize_in_thread() {
53 this->record_stack_base_and_size();
54 this->initialize_thread_local_storage();
55 this->initialize_named_thread();
56 this->set_active_handles(JNIHandleBlock::allocate_block());
57 // From this time Thread::current() should be working.
58 assert(this == Thread::current(), "just checking");
59 }
60
61 void ConcurrentGCThread::wait_for_universe_init() {
62 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
63 while (!is_init_completed() && !_should_terminate) {
64 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
65 }
66 }
67
68 void ConcurrentGCThread::terminate() {
69 assert(_should_terminate, "Should only be called on terminate request.");
70 // Signal that it is terminated
71 {
72 MutexLockerEx mu(Terminator_lock,
73 Mutex::_no_safepoint_check_flag);
74 _has_terminated = true;
75 Terminator_lock->notify();
76 }
77
78 // Thread destructor usually does this..
79 ThreadLocalStorage::set_thread(NULL);
80 }
81
82 static void _sltLoop(JavaThread* thread, TRAPS) {
83 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
84 slt->loop();
85 }
86
87 SurrogateLockerThread::SurrogateLockerThread() :
88 JavaThread(&_sltLoop),
89 _monitor(Mutex::nonleaf, "SLTMonitor", false,
90 Monitor::_safepoint_check_sometimes),
91 _buffer(empty)
92 {}
93
94 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
95 Klass* k =
96 SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(),
97 true, CHECK_NULL);
98 instanceKlassHandle klass (THREAD, k);
99 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
100
101 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)";
102 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
103
104 // Initialize thread_oop to put it into the system threadGroup
105 Handle thread_group (THREAD, Universe::system_thread_group());
106 JavaValue result(T_VOID);
107 JavaCalls::call_special(&result, thread_oop,
108 klass,
109 vmSymbols::object_initializer_name(),
110 vmSymbols::threadgroup_string_void_signature(),
111 thread_group,
112 string,
113 CHECK_NULL);
114
115 SurrogateLockerThread* res;
116 {
117 MutexLocker mu(Threads_lock);
118 res = new SurrogateLockerThread();
119
120 // At this point it may be possible that no osthread was created for the
121 // JavaThread due to lack of memory. We would have to throw an exception
122 // in that case. However, since this must work and we do not allow
123 // exceptions anyway, check and abort if this fails.
124 if (res == NULL || res->osthread() == NULL) {
125 vm_exit_during_initialization("java.lang.OutOfMemoryError",
126 os::native_thread_creation_failed_msg());
127 }
128 java_lang_Thread::set_thread(thread_oop(), res);
129 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
130 java_lang_Thread::set_daemon(thread_oop());
131
132 res->set_threadObj(thread_oop());
133 Threads::add(res);
134 Thread::start(res);
135 }
136 os::naked_yield(); // This seems to help with initial start-up of SLT
137 return res;
138 }
139
140 void SurrogateLockerThread::report_missing_slt() {
141 vm_exit_during_initialization(
142 "GC before GC support fully initialized: "
143 "SLT is needed but has not yet been created.");
144 ShouldNotReachHere();
145 }
146
147 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
148 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
149 assert(_buffer == empty, "Should be empty");
150 assert(msg != empty, "empty message");
151 assert(!Heap_lock->owned_by_self(), "Heap_lock owned by requesting thread");
152
153 _buffer = msg;
154 while (_buffer != empty) {
155 _monitor.notify();
156 _monitor.wait(Mutex::_no_safepoint_check_flag);
157 }
158 }
159
160 // ======= Surrogate Locker Thread =============
161
162 void SurrogateLockerThread::loop() {
163 BasicLock pll_basic_lock;
164 SLT_msg_type msg;
165 debug_only(unsigned int owned = 0;)
166
167 while (/* !isTerminated() */ 1) {
168 {
169 MutexLocker x(&_monitor);
170 // Since we are a JavaThread, we can't be here at a safepoint.
171 assert(!SafepointSynchronize::is_at_safepoint(),
172 "SLT is a JavaThread");
173 // wait for msg buffer to become non-empty
174 while (_buffer == empty) {
175 _monitor.notify();
176 _monitor.wait();
177 }
178 msg = _buffer;
179 }
180 switch(msg) {
181 case acquirePLL: {
182 InstanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
183 debug_only(owned++;)
184 break;
185 }
186 case releaseAndNotifyPLL: {
187 assert(owned > 0, "Don't have PLL");
188 InstanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
189 debug_only(owned--;)
190 break;
191 }
192 case empty:
193 default: {
194 guarantee(false,"Unexpected message in _buffer");
195 break;
196 }
197 }
198 {
199 MutexLocker x(&_monitor);
200 // Since we are a JavaThread, we can't be here at a safepoint.
201 assert(!SafepointSynchronize::is_at_safepoint(),
202 "SLT is a JavaThread");
203 _buffer = empty;
204 _monitor.notify();
205 }
206 }
207 assert(!_monitor.owned_by_self(), "Should unlock before exit.");
208 }