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1 /*
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2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // CopyrightVersion 1.2
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26
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27 # include "incls/_precompiled.incl"
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28 # include "incls/_concurrentGCThread.cpp.incl"
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29
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30 int ConcurrentGCThread::_CGC_flag = CGC_nil;
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31
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32 SuspendibleThreadSet ConcurrentGCThread::_sts;
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33
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34 ConcurrentGCThread::ConcurrentGCThread() :
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35 _should_terminate(false), _has_terminated(false) {
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36 _sts.initialize();
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37 };
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38
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39 void ConcurrentGCThread::stopWorldAndDo(VoidClosure* op) {
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40 MutexLockerEx x(Heap_lock,
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41 Mutex::_no_safepoint_check_flag);
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42 // warning("CGC: about to try stopping world");
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43 SafepointSynchronize::begin();
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44 // warning("CGC: successfully stopped world");
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45 op->do_void();
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46 SafepointSynchronize::end();
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47 // warning("CGC: successfully restarted world");
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48 }
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49
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50 void ConcurrentGCThread::safepoint_synchronize() {
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51 _sts.suspend_all();
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52 }
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53
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54 void ConcurrentGCThread::safepoint_desynchronize() {
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55 _sts.resume_all();
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56 }
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57
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58 void ConcurrentGCThread::create_and_start() {
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59 if (os::create_thread(this, os::cgc_thread)) {
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60 // XXX: need to set this to low priority
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61 // unless "agressive mode" set; priority
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62 // should be just less than that of VMThread.
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63 os::set_priority(this, NearMaxPriority);
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64 if (!_should_terminate && !DisableStartThread) {
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65 os::start_thread(this);
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66 }
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67 }
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68 }
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69
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70 void ConcurrentGCThread::initialize_in_thread() {
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71 this->record_stack_base_and_size();
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72 this->initialize_thread_local_storage();
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73 this->set_active_handles(JNIHandleBlock::allocate_block());
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74 // From this time Thread::current() should be working.
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75 assert(this == Thread::current(), "just checking");
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76 }
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77
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78 void ConcurrentGCThread::wait_for_universe_init() {
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79 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
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80 while (!is_init_completed() && !_should_terminate) {
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81 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
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82 }
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83 }
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84
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85 void ConcurrentGCThread::terminate() {
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86 // Signal that it is terminated
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87 {
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88 MutexLockerEx mu(Terminator_lock,
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89 Mutex::_no_safepoint_check_flag);
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90 _has_terminated = true;
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91 Terminator_lock->notify();
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92 }
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93
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94 // Thread destructor usually does this..
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95 ThreadLocalStorage::set_thread(NULL);
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96 }
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97
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98
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99 void SuspendibleThreadSet::initialize_work() {
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100 MutexLocker x(STS_init_lock);
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101 if (!_initialized) {
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102 _m = new Monitor(Mutex::leaf,
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103 "SuspendibleThreadSetLock", true);
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104 _async = 0;
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105 _async_stop = false;
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106 _async_stopped = 0;
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107 _initialized = true;
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108 }
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109 }
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110
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111 void SuspendibleThreadSet::join() {
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112 initialize();
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113 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
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114 while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
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115 _async++;
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116 assert(_async > 0, "Huh.");
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117 }
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118
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119 void SuspendibleThreadSet::leave() {
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120 assert(_initialized, "Must be initialized.");
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121 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
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122 _async--;
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123 assert(_async >= 0, "Huh.");
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124 if (_async_stop) _m->notify_all();
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125 }
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126
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127 void SuspendibleThreadSet::yield(const char* id) {
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128 assert(_initialized, "Must be initialized.");
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129 if (_async_stop) {
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130 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
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131 if (_async_stop) {
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132 _async_stopped++;
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133 assert(_async_stopped > 0, "Huh.");
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134 if (_async_stopped == _async) {
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135 if (ConcGCYieldTimeout > 0) {
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136 double now = os::elapsedTime();
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137 guarantee((now - _suspend_all_start) * 1000.0 <
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138 (double)ConcGCYieldTimeout,
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139 "Long delay; whodunit?");
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140 }
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141 }
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142 _m->notify_all();
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143 while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
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144 _async_stopped--;
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145 assert(_async >= 0, "Huh");
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146 _m->notify_all();
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147 }
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148 }
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149 }
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150
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151 void SuspendibleThreadSet::suspend_all() {
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152 initialize(); // If necessary.
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153 if (ConcGCYieldTimeout > 0) {
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154 _suspend_all_start = os::elapsedTime();
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155 }
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156 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
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157 assert(!_async_stop, "Only one at a time.");
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158 _async_stop = true;
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159 while (_async_stopped < _async) _m->wait(Mutex::_no_safepoint_check_flag);
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160 }
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161
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162 void SuspendibleThreadSet::resume_all() {
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163 assert(_initialized, "Must be initialized.");
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164 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
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165 assert(_async_stopped == _async, "Huh.");
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166 _async_stop = false;
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167 _m->notify_all();
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168 }
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169
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170 static void _sltLoop(JavaThread* thread, TRAPS) {
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171 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
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172 slt->loop();
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173 }
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174
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175 SurrogateLockerThread::SurrogateLockerThread() :
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176 JavaThread(&_sltLoop),
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177 _monitor(Mutex::nonleaf, "SLTMonitor"),
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178 _buffer(empty)
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179 {}
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180
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181 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
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182 klassOop k =
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183 SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(),
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184 true, CHECK_NULL);
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185 instanceKlassHandle klass (THREAD, k);
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186 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
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187
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188 const char thread_name[] = "Surrogate Locker Thread (CMS)";
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189 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
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190
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191 // Initialize thread_oop to put it into the system threadGroup
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192 Handle thread_group (THREAD, Universe::system_thread_group());
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193 JavaValue result(T_VOID);
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194 JavaCalls::call_special(&result, thread_oop,
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195 klass,
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196 vmSymbolHandles::object_initializer_name(),
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197 vmSymbolHandles::threadgroup_string_void_signature(),
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198 thread_group,
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199 string,
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200 CHECK_NULL);
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201
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202 SurrogateLockerThread* res;
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203 {
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204 MutexLocker mu(Threads_lock);
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205 res = new SurrogateLockerThread();
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206
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207 // At this point it may be possible that no osthread was created for the
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208 // JavaThread due to lack of memory. We would have to throw an exception
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209 // in that case. However, since this must work and we do not allow
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210 // exceptions anyway, check and abort if this fails.
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211 if (res == NULL || res->osthread() == NULL) {
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212 vm_exit_during_initialization("java.lang.OutOfMemoryError",
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213 "unable to create new native thread");
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214 }
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215 java_lang_Thread::set_thread(thread_oop(), res);
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216 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
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217 java_lang_Thread::set_daemon(thread_oop());
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218
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219 res->set_threadObj(thread_oop());
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220 Threads::add(res);
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221 Thread::start(res);
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222 }
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223 os::yield(); // This seems to help with initial start-up of SLT
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224 return res;
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225 }
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226
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227 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
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228 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
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229 assert(_buffer == empty, "Should be empty");
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230 assert(msg != empty, "empty message");
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231 _buffer = msg;
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232 while (_buffer != empty) {
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233 _monitor.notify();
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234 _monitor.wait(Mutex::_no_safepoint_check_flag);
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235 }
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236 }
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237
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238 // ======= Surrogate Locker Thread =============
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239
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240 void SurrogateLockerThread::loop() {
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241 BasicLock pll_basic_lock;
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242 SLT_msg_type msg;
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243 debug_only(unsigned int owned = 0;)
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244
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245 while (/* !isTerminated() */ 1) {
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246 {
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247 MutexLocker x(&_monitor);
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248 // Since we are a JavaThread, we can't be here at a safepoint.
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249 assert(!SafepointSynchronize::is_at_safepoint(),
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250 "SLT is a JavaThread");
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251 // wait for msg buffer to become non-empty
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252 while (_buffer == empty) {
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253 _monitor.notify();
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254 _monitor.wait();
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255 }
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256 msg = _buffer;
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257 }
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258 switch(msg) {
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259 case acquirePLL: {
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260 instanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
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261 debug_only(owned++;)
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262 break;
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263 }
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264 case releaseAndNotifyPLL: {
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265 assert(owned > 0, "Don't have PLL");
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266 instanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
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267 debug_only(owned--;)
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268 break;
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269 }
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270 case empty:
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271 default: {
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272 guarantee(false,"Unexpected message in _buffer");
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273 break;
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274 }
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275 }
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276 {
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277 MutexLocker x(&_monitor);
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278 // Since we are a JavaThread, we can't be here at a safepoint.
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279 assert(!SafepointSynchronize::is_at_safepoint(),
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280 "SLT is a JavaThread");
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281 _buffer = empty;
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282 _monitor.notify();
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283 }
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284 }
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285 assert(!_monitor.owned_by_self(), "Should unlock before exit.");
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286 }
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287
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288
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289 // ===== STS Access From Outside CGCT =====
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290
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291 void ConcurrentGCThread::stsYield(const char* id) {
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292 assert( Thread::current()->is_ConcurrentGC_thread(),
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293 "only a conc GC thread can call this" );
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294 _sts.yield(id);
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295 }
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296
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297 bool ConcurrentGCThread::stsShouldYield() {
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298 assert( Thread::current()->is_ConcurrentGC_thread(),
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299 "only a conc GC thread can call this" );
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300 return _sts.should_yield();
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301 }
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302
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303 void ConcurrentGCThread::stsJoin() {
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304 assert( Thread::current()->is_ConcurrentGC_thread(),
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305 "only a conc GC thread can call this" );
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306 _sts.join();
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307 }
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308
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309 void ConcurrentGCThread::stsLeave() {
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310 assert( Thread::current()->is_ConcurrentGC_thread(),
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311 "only a conc GC thread can call this" );
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312 _sts.leave();
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313 }
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