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_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->initialize_named_thread();
60 this->set_active_handles(JNIHandleBlock::allocate_block());
61 // From this time Thread::current() should be working.
62 assert(this == Thread::current(), "just checking");
63 }
64
65 void ConcurrentGCThread::wait_for_universe_init() {
66 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
67 while (!is_init_completed() && !_should_terminate) {
68 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
69 }
70 }
71
72 void ConcurrentGCThread::terminate() {
73 // Signal that it is terminated
74 {
75 MutexLockerEx mu(Terminator_lock,
76 Mutex::_no_safepoint_check_flag);
77 _has_terminated = true;
78 Terminator_lock->notify();
79 }
80
81 // Thread destructor usually does this..
82 ThreadLocalStorage::set_thread(NULL);
83 }
84
85 static void _sltLoop(JavaThread* thread, TRAPS) {
86 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
87 slt->loop();
88 }
89
90 SurrogateLockerThread::SurrogateLockerThread() :
91 JavaThread(&_sltLoop),
92 _monitor(Mutex::nonleaf, "SLTMonitor", false,
93 Monitor::_safepoint_check_sometimes),
94 _buffer(empty)
95 {}
96
97 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
98 Klass* k =
99 SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(),
100 true, CHECK_NULL);
101 instanceKlassHandle klass (THREAD, k);
102 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
103
104 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)";
105 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
106
107 // Initialize thread_oop to put it into the system threadGroup
108 Handle thread_group (THREAD, Universe::system_thread_group());
109 JavaValue result(T_VOID);
110 JavaCalls::call_special(&result, thread_oop,
111 klass,
112 vmSymbols::object_initializer_name(),
113 vmSymbols::threadgroup_string_void_signature(),
114 thread_group,
115 string,
116 CHECK_NULL);
117
118 SurrogateLockerThread* res;
119 {
120 MutexLocker mu(Threads_lock);
121 res = new SurrogateLockerThread();
122
123 // At this point it may be possible that no osthread was created for the
124 // JavaThread due to lack of memory. We would have to throw an exception
125 // in that case. However, since this must work and we do not allow
126 // exceptions anyway, check and abort if this fails.
127 if (res == NULL || res->osthread() == NULL) {
128 vm_exit_during_initialization("java.lang.OutOfMemoryError",
129 os::native_thread_creation_failed_msg());
130 }
131 java_lang_Thread::set_thread(thread_oop(), res);
132 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
133 java_lang_Thread::set_daemon(thread_oop());
134
135 res->set_threadObj(thread_oop());
136 Threads::add(res);
137 Thread::start(res);
138 }
139 os::naked_yield(); // This seems to help with initial start-up of SLT
140 return res;
141 }
142
143 void SurrogateLockerThread::report_missing_slt() {
144 vm_exit_during_initialization(
145 "GC before GC support fully initialized: "
146 "SLT is needed but has not yet been created.");
147 ShouldNotReachHere();
148 }
149
150 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
151 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
152 assert(_buffer == empty, "Should be empty");
153 assert(msg != empty, "empty message");
154 assert(!Heap_lock->owned_by_self(), "Heap_lock owned by requesting thread");
155
156 _buffer = msg;
157 while (_buffer != empty) {
158 _monitor.notify();
159 _monitor.wait(Mutex::_no_safepoint_check_flag);
160 }
161 }
162
163 // ======= Surrogate Locker Thread =============
164
165 void SurrogateLockerThread::loop() {
166 BasicLock pll_basic_lock;
167 SLT_msg_type msg;
168 debug_only(unsigned int owned = 0;)
169
170 while (/* !isTerminated() */ 1) {
171 {
172 MutexLocker x(&_monitor);
173 // Since we are a JavaThread, we can't be here at a safepoint.
174 assert(!SafepointSynchronize::is_at_safepoint(),
175 "SLT is a JavaThread");
176 // wait for msg buffer to become non-empty
177 while (_buffer == empty) {
178 _monitor.notify();
179 _monitor.wait();
180 }
181 msg = _buffer;
182 }
183 switch(msg) {
184 case acquirePLL: {
185 InstanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
186 debug_only(owned++;)
187 break;
188 }
189 case releaseAndNotifyPLL: {
190 assert(owned > 0, "Don't have PLL");
191 InstanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
192 debug_only(owned--;)
193 break;
194 }
195 case empty:
196 default: {
197 guarantee(false,"Unexpected message in _buffer");
198 break;
199 }
200 }
201 {
202 MutexLocker x(&_monitor);
203 // Since we are a JavaThread, we can't be here at a safepoint.
204 assert(!SafepointSynchronize::is_at_safepoint(),
205 "SLT is a JavaThread");
206 _buffer = empty;
207 _monitor.notify();
208 }
209 }
210 assert(!_monitor.owned_by_self(), "Should unlock before exit.");
211 }