1 /*
2 * Copyright (c) 2001, 2014, 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 #include "runtime/os.hpp"
35
36 // CopyrightVersion 1.2
37
38 int ConcurrentGCThread::_CGC_flag = CGC_nil;
39
40 ConcurrentGCThread::ConcurrentGCThread() :
41 _should_terminate(false), _has_terminated(false) {
42 };
43
44 void ConcurrentGCThread::create_and_start() {
45 if (os::create_thread(this, os::cgc_thread)) {
46 // XXX: need to set this to low priority
47 // unless "aggressive mode" set; priority
48 // should be just less than that of VMThread.
49 os::set_priority(this, NearMaxPriority);
50 if (!_should_terminate && !DisableStartThread) {
51 os::start_thread(this);
52 }
53 }
54 }
55
56 void ConcurrentGCThread::initialize_in_thread() {
57 this->record_stack_base_and_size();
58 this->initialize_thread_local_storage();
59 this->set_active_handles(JNIHandleBlock::allocate_block());
60 // From this time Thread::current() should be working.
61 assert(this == Thread::current(), "just checking");
62 }
63
64 void ConcurrentGCThread::wait_for_universe_init() {
65 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
66 while (!is_init_completed() && !_should_terminate) {
67 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
68 }
69 }
70
71 void ConcurrentGCThread::terminate() {
72 // Signal that it is terminated
73 {
74 MutexLockerEx mu(Terminator_lock,
75 Mutex::_no_safepoint_check_flag);
76 _has_terminated = true;
77 Terminator_lock->notify();
78 }
79
80 // Thread destructor usually does this..
81 ThreadLocalStorage::set_thread(NULL);
82 }
83
84 static void _sltLoop(JavaThread* thread, TRAPS) {
85 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
86 slt->loop();
87 }
88
89 SurrogateLockerThread::SurrogateLockerThread() :
90 JavaThread(&_sltLoop),
91 _monitor(Mutex::nonleaf, "SLTMonitor", false,
92 Monitor::_safepoint_check_sometimes),
93 _buffer(empty)
94 {}
95
96 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
97 Klass* k =
98 SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(),
99 true, CHECK_NULL);
100 instanceKlassHandle klass (THREAD, k);
101 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
102
103 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)";
104 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
105
106 // Initialize thread_oop to put it into the system threadGroup
107 Handle thread_group (THREAD, Universe::system_thread_group());
108 JavaValue result(T_VOID);
109 JavaCalls::call_special(&result, thread_oop,
110 klass,
111 vmSymbols::object_initializer_name(),
112 vmSymbols::threadgroup_string_void_signature(),
113 thread_group,
114 string,
115 CHECK_NULL);
116
117 SurrogateLockerThread* res;
118 {
119 MutexLocker mu(Threads_lock);
120 res = new SurrogateLockerThread();
121
122 // At this point it may be possible that no osthread was created for the
123 // JavaThread due to lack of memory. We would have to throw an exception
124 // in that case. However, since this must work and we do not allow
125 // exceptions anyway, check and abort if this fails.
126 if (res == NULL || res->osthread() == NULL) {
127 vm_exit_during_initialization("java.lang.OutOfMemoryError",
128 os::native_thread_creation_failed_msg());
129 }
130 java_lang_Thread::set_thread(thread_oop(), res);
131 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
132 java_lang_Thread::set_daemon(thread_oop());
133
134 res->set_threadObj(thread_oop());
135 Threads::add(res);
136 Thread::start(res);
137 }
138 os::naked_yield(); // This seems to help with initial start-up of SLT
139 return res;
140 }
141
142 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
143 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
144 assert(_buffer == empty, "Should be empty");
145 assert(msg != empty, "empty message");
146 assert(!Heap_lock->owned_by_self(), "Heap_lock owned by requesting thread");
147
148 _buffer = msg;
149 while (_buffer != empty) {
150 _monitor.notify();
151 _monitor.wait(Mutex::_no_safepoint_check_flag);
152 }
153 }
154
155 // ======= Surrogate Locker Thread =============
156
157 void SurrogateLockerThread::loop() {
158 BasicLock pll_basic_lock;
159 SLT_msg_type msg;
160 debug_only(unsigned int owned = 0;)
161
162 while (/* !isTerminated() */ 1) {
163 {
164 MutexLocker x(&_monitor);
165 // Since we are a JavaThread, we can't be here at a safepoint.
166 assert(!SafepointSynchronize::is_at_safepoint(),
167 "SLT is a JavaThread");
168 // wait for msg buffer to become non-empty
169 while (_buffer == empty) {
170 _monitor.notify();
171 _monitor.wait();
172 }
173 msg = _buffer;
174 }
175 switch(msg) {
176 case acquirePLL: {
177 InstanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
178 debug_only(owned++;)
179 break;
180 }
181 case releaseAndNotifyPLL: {
182 assert(owned > 0, "Don't have PLL");
183 InstanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
184 debug_only(owned--;)
185 break;
186 }
187 case empty:
188 default: {
189 guarantee(false,"Unexpected message in _buffer");
190 break;
191 }
192 }
193 {
194 MutexLocker x(&_monitor);
195 // Since we are a JavaThread, we can't be here at a safepoint.
196 assert(!SafepointSynchronize::is_at_safepoint(),
197 "SLT is a JavaThread");
198 _buffer = empty;
199 _monitor.notify();
200 }
201 }
202 assert(!_monitor.owned_by_self(), "Should unlock before exit.");
203 }