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1 /* |
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2 * Copyright 1997-2007 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 # include "incls/_precompiled.incl" |
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26 # include "incls/_safepoint.cpp.incl" |
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27 |
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28 // -------------------------------------------------------------------------------------------------- |
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29 // Implementation of Safepoint begin/end |
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30 |
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31 SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; |
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32 volatile int SafepointSynchronize::_waiting_to_block = 0; |
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33 jlong SafepointSynchronize::_last_safepoint = 0; |
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34 volatile int SafepointSynchronize::_safepoint_counter = 0; |
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35 static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
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36 static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only |
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37 static bool timeout_error_printed = false; |
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38 |
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39 // Roll all threads forward to a safepoint and suspend them all |
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40 void SafepointSynchronize::begin() { |
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41 |
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42 Thread* myThread = Thread::current(); |
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43 assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); |
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44 |
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45 _last_safepoint = os::javaTimeNanos(); |
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46 |
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47 #ifndef SERIALGC |
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48 if (UseConcMarkSweepGC) { |
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49 // In the future we should investigate whether CMS can use the |
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50 // more-general mechanism below. DLD (01/05). |
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51 ConcurrentMarkSweepThread::synchronize(false); |
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52 } else { |
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53 ConcurrentGCThread::safepoint_synchronize(); |
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54 } |
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55 #endif // SERIALGC |
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56 |
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57 // By getting the Threads_lock, we assure that no threads are about to start or |
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58 // exit. It is released again in SafepointSynchronize::end(). |
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59 Threads_lock->lock(); |
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60 |
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61 assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); |
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62 |
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63 int nof_threads = Threads::number_of_threads(); |
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64 |
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65 if (TraceSafepoint) { |
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66 tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads); |
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67 } |
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68 |
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69 RuntimeService::record_safepoint_begin(); |
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70 |
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71 { |
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72 MutexLocker mu(Safepoint_lock); |
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73 |
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74 // Set number of threads to wait for, before we initiate the callbacks |
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75 _waiting_to_block = nof_threads; |
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76 TryingToBlock = 0 ; |
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77 int still_running = nof_threads; |
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78 |
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79 // Save the starting time, so that it can be compared to see if this has taken |
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80 // too long to complete. |
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81 jlong safepoint_limit_time; |
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82 timeout_error_printed = false; |
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83 |
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84 // Begin the process of bringing the system to a safepoint. |
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85 // Java threads can be in several different states and are |
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86 // stopped by different mechanisms: |
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87 // |
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88 // 1. Running interpreted |
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89 // The interpeter dispatch table is changed to force it to |
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90 // check for a safepoint condition between bytecodes. |
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91 // 2. Running in native code |
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92 // When returning from the native code, a Java thread must check |
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93 // the safepoint _state to see if we must block. If the |
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94 // VM thread sees a Java thread in native, it does |
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95 // not wait for this thread to block. The order of the memory |
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96 // writes and reads of both the safepoint state and the Java |
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97 // threads state is critical. In order to guarantee that the |
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98 // memory writes are serialized with respect to each other, |
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99 // the VM thread issues a memory barrier instruction |
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100 // (on MP systems). In order to avoid the overhead of issuing |
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101 // a memory barrier for each Java thread making native calls, each Java |
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102 // thread performs a write to a single memory page after changing |
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103 // the thread state. The VM thread performs a sequence of |
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104 // mprotect OS calls which forces all previous writes from all |
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105 // Java threads to be serialized. This is done in the |
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106 // os::serialize_thread_states() call. This has proven to be |
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107 // much more efficient than executing a membar instruction |
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108 // on every call to native code. |
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109 // 3. Running compiled Code |
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110 // Compiled code reads a global (Safepoint Polling) page that |
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111 // is set to fault if we are trying to get to a safepoint. |
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112 // 4. Blocked |
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113 // A thread which is blocked will not be allowed to return from the |
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114 // block condition until the safepoint operation is complete. |
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115 // 5. In VM or Transitioning between states |
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116 // If a Java thread is currently running in the VM or transitioning |
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117 // between states, the safepointing code will wait for the thread to |
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118 // block itself when it attempts transitions to a new state. |
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119 // |
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120 _state = _synchronizing; |
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121 OrderAccess::fence(); |
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122 |
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123 // Flush all thread states to memory |
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124 if (!UseMembar) { |
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125 os::serialize_thread_states(); |
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126 } |
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127 |
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128 // Make interpreter safepoint aware |
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129 Interpreter::notice_safepoints(); |
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130 |
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131 if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) { |
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132 // Make polling safepoint aware |
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133 guarantee (PageArmed == 0, "invariant") ; |
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134 PageArmed = 1 ; |
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135 os::make_polling_page_unreadable(); |
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136 } |
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137 |
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138 // Consider using active_processor_count() ... but that call is expensive. |
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139 int ncpus = os::processor_count() ; |
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140 |
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141 #ifdef ASSERT |
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142 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
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143 assert(cur->safepoint_state()->is_running(), "Illegal initial state"); |
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144 } |
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145 #endif // ASSERT |
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146 |
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147 if (SafepointTimeout) |
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148 safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; |
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149 |
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150 // Iterate through all threads until it have been determined how to stop them all at a safepoint |
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151 unsigned int iterations = 0; |
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152 int steps = 0 ; |
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153 while(still_running > 0) { |
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154 for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
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155 assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); |
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156 ThreadSafepointState *cur_state = cur->safepoint_state(); |
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157 if (cur_state->is_running()) { |
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158 cur_state->examine_state_of_thread(); |
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159 if (!cur_state->is_running()) { |
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160 still_running--; |
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161 // consider adjusting steps downward: |
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162 // steps = 0 |
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163 // steps -= NNN |
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164 // steps >>= 1 |
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165 // steps = MIN(steps, 2000-100) |
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166 // if (iterations != 0) steps -= NNN |
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167 } |
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168 if (TraceSafepoint && Verbose) cur_state->print(); |
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169 } |
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170 } |
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171 |
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172 if ( (PrintSafepointStatistics || (PrintSafepointStatisticsTimeout > 0)) |
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173 && iterations == 0) { |
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174 begin_statistics(nof_threads, still_running); |
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175 } |
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176 |
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177 if (still_running > 0) { |
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178 // Check for if it takes to long |
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179 if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { |
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180 print_safepoint_timeout(_spinning_timeout); |
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181 } |
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182 |
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183 // Spin to avoid context switching. |
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184 // There's a tension between allowing the mutators to run (and rendezvous) |
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185 // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that |
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186 // a mutator might otherwise use profitably to reach a safepoint. Excessive |
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187 // spinning by the VM thread on a saturated system can increase rendezvous latency. |
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188 // Blocking or yielding incur their own penalties in the form of context switching |
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189 // and the resultant loss of $ residency. |
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190 // |
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191 // Further complicating matters is that yield() does not work as naively expected |
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192 // on many platforms -- yield() does not guarantee that any other ready threads |
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193 // will run. As such we revert yield_all() after some number of iterations. |
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194 // Yield_all() is implemented as a short unconditional sleep on some platforms. |
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195 // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping |
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196 // can actually increase the time it takes the VM thread to detect that a system-wide |
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197 // stop-the-world safepoint has been reached. In a pathological scenario such as that |
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198 // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. |
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199 // In that case the mutators will be stalled waiting for the safepoint to complete and the |
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200 // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread |
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201 // will eventually wake up and detect that all mutators are safe, at which point |
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202 // we'll again make progress. |
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203 // |
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204 // Beware too that that the VMThread typically runs at elevated priority. |
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205 // Its default priority is higher than the default mutator priority. |
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206 // Obviously, this complicates spinning. |
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207 // |
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208 // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). |
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209 // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. |
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210 // |
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211 // See the comments in synchronizer.cpp for additional remarks on spinning. |
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212 // |
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213 // In the future we might: |
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214 // 1. Modify the safepoint scheme to avoid potentally unbounded spinning. |
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215 // This is tricky as the path used by a thread exiting the JVM (say on |
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216 // on JNI call-out) simply stores into its state field. The burden |
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217 // is placed on the VM thread, which must poll (spin). |
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218 // 2. Find something useful to do while spinning. If the safepoint is GC-related |
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219 // we might aggressively scan the stacks of threads that are already safe. |
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220 // 3. Use Solaris schedctl to examine the state of the still-running mutators. |
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221 // If all the mutators are ONPROC there's no reason to sleep or yield. |
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222 // 4. YieldTo() any still-running mutators that are ready but OFFPROC. |
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223 // 5. Check system saturation. If the system is not fully saturated then |
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224 // simply spin and avoid sleep/yield. |
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225 // 6. As still-running mutators rendezvous they could unpark the sleeping |
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226 // VMthread. This works well for still-running mutators that become |
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227 // safe. The VMthread must still poll for mutators that call-out. |
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228 // 7. Drive the policy on time-since-begin instead of iterations. |
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229 // 8. Consider making the spin duration a function of the # of CPUs: |
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230 // Spin = (((ncpus-1) * M) + K) + F(still_running) |
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231 // Alternately, instead of counting iterations of the outer loop |
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232 // we could count the # of threads visited in the inner loop, above. |
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233 // 9. On windows consider using the return value from SwitchThreadTo() |
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234 // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. |
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235 |
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236 if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) { |
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237 guarantee (PageArmed == 0, "invariant") ; |
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238 PageArmed = 1 ; |
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239 os::make_polling_page_unreadable(); |
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240 } |
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241 |
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242 // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or |
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243 // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) |
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244 ++steps ; |
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245 if (ncpus > 1 && steps < SafepointSpinBeforeYield) { |
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246 SpinPause() ; // MP-Polite spin |
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247 } else |
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248 if (steps < DeferThrSuspendLoopCount) { |
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249 os::NakedYield() ; |
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250 } else { |
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251 os::yield_all(steps) ; |
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252 // Alternately, the VM thread could transiently depress its scheduling priority or |
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253 // transiently increase the priority of the tardy mutator(s). |
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254 } |
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255 |
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256 iterations ++ ; |
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257 } |
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258 assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); |
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259 } |
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260 assert(still_running == 0, "sanity check"); |
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261 |
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262 if (PrintSafepointStatistics) { |
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263 update_statistics_on_spin_end(); |
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264 } |
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265 |
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266 // wait until all threads are stopped |
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267 while (_waiting_to_block > 0) { |
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268 if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block); |
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269 if (!SafepointTimeout || timeout_error_printed) { |
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270 Safepoint_lock->wait(true); // true, means with no safepoint checks |
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271 } else { |
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272 // Compute remaining time |
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273 jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); |
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274 |
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275 // If there is no remaining time, then there is an error |
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276 if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { |
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277 print_safepoint_timeout(_blocking_timeout); |
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278 } |
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279 } |
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280 } |
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281 assert(_waiting_to_block == 0, "sanity check"); |
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282 |
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283 #ifndef PRODUCT |
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284 if (SafepointTimeout) { |
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285 jlong current_time = os::javaTimeNanos(); |
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286 if (safepoint_limit_time < current_time) { |
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287 tty->print_cr("# SafepointSynchronize: Finished after " |
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288 INT64_FORMAT_W(6) " ms", |
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289 ((current_time - safepoint_limit_time) / MICROUNITS + |
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290 SafepointTimeoutDelay)); |
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291 } |
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292 } |
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293 #endif |
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294 |
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295 assert((_safepoint_counter & 0x1) == 0, "must be even"); |
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296 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); |
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297 _safepoint_counter ++; |
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298 |
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299 // Record state |
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300 _state = _synchronized; |
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301 |
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302 OrderAccess::fence(); |
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303 |
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304 if (TraceSafepoint) { |
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305 VM_Operation *op = VMThread::vm_operation(); |
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306 tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation"); |
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307 } |
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308 |
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309 RuntimeService::record_safepoint_synchronized(); |
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310 if (PrintSafepointStatistics) { |
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311 update_statistics_on_sync_end(os::javaTimeNanos()); |
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312 } |
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313 |
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314 // Call stuff that needs to be run when a safepoint is just about to be completed |
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315 do_cleanup_tasks(); |
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316 } |
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317 } |
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318 |
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319 // Wake up all threads, so they are ready to resume execution after the safepoint |
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320 // operation has been carried out |
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321 void SafepointSynchronize::end() { |
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322 |
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323 assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); |
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324 assert((_safepoint_counter & 0x1) == 1, "must be odd"); |
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325 _safepoint_counter ++; |
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326 // memory fence isn't required here since an odd _safepoint_counter |
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327 // value can do no harm and a fence is issued below anyway. |
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328 |
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329 DEBUG_ONLY(Thread* myThread = Thread::current();) |
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330 assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); |
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331 |
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332 if (PrintSafepointStatistics) { |
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333 end_statistics(os::javaTimeNanos()); |
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334 } |
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335 |
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336 #ifdef ASSERT |
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337 // A pending_exception cannot be installed during a safepoint. The threads |
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338 // may install an async exception after they come back from a safepoint into |
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339 // pending_exception after they unblock. But that should happen later. |
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340 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { |
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341 assert (!(cur->has_pending_exception() && |
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342 cur->safepoint_state()->is_at_poll_safepoint()), |
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343 "safepoint installed a pending exception"); |
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344 } |
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345 #endif // ASSERT |
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346 |
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347 if (PageArmed) { |
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348 // Make polling safepoint aware |
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349 os::make_polling_page_readable(); |
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350 PageArmed = 0 ; |
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351 } |
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352 |
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353 // Remove safepoint check from interpreter |
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354 Interpreter::ignore_safepoints(); |
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355 |
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356 { |
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357 MutexLocker mu(Safepoint_lock); |
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358 |
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359 assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); |
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360 |
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361 // Set to not synchronized, so the threads will not go into the signal_thread_blocked method |
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362 // when they get restarted. |
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363 _state = _not_synchronized; |
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364 OrderAccess::fence(); |
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365 |
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366 if (TraceSafepoint) { |
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367 tty->print_cr("Leaving safepoint region"); |
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368 } |
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369 |
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370 // Start suspended threads |
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371 for(JavaThread *current = Threads::first(); current; current = current->next()) { |
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372 // A problem occuring on Solaris is when attempting to restart threads |
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373 // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
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374 // to the next one (since it has been running the longest). We then have |
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375 // to wait for a cpu to become available before we can continue restarting |
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376 // threads. |
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377 // FIXME: This causes the performance of the VM to degrade when active and with |
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378 // large numbers of threads. Apparently this is due to the synchronous nature |
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379 // of suspending threads. |
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380 // |
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381 // TODO-FIXME: the comments above are vestigial and no longer apply. |
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382 // Furthermore, using solaris' schedctl in this particular context confers no benefit |
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383 if (VMThreadHintNoPreempt) { |
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384 os::hint_no_preempt(); |
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385 } |
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386 ThreadSafepointState* cur_state = current->safepoint_state(); |
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387 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); |
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388 cur_state->restart(); |
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389 assert(cur_state->is_running(), "safepoint state has not been reset"); |
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390 } |
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391 |
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392 RuntimeService::record_safepoint_end(); |
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393 |
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394 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads |
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395 // blocked in signal_thread_blocked |
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396 Threads_lock->unlock(); |
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397 |
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398 } |
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399 #ifndef SERIALGC |
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400 // If there are any concurrent GC threads resume them. |
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401 if (UseConcMarkSweepGC) { |
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402 ConcurrentMarkSweepThread::desynchronize(false); |
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403 } else { |
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404 ConcurrentGCThread::safepoint_desynchronize(); |
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405 } |
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406 #endif // SERIALGC |
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407 } |
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408 |
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409 bool SafepointSynchronize::is_cleanup_needed() { |
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410 // Need a safepoint if some inline cache buffers is non-empty |
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411 if (!InlineCacheBuffer::is_empty()) return true; |
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412 return false; |
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413 } |
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414 |
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415 jlong CounterDecay::_last_timestamp = 0; |
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416 |
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417 static void do_method(methodOop m) { |
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418 m->invocation_counter()->decay(); |
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419 } |
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420 |
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421 void CounterDecay::decay() { |
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422 _last_timestamp = os::javaTimeMillis(); |
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423 |
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424 // This operation is going to be performed only at the end of a safepoint |
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425 // and hence GC's will not be going on, all Java mutators are suspended |
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426 // at this point and hence SystemDictionary_lock is also not needed. |
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427 assert(SafepointSynchronize::is_at_safepoint(), "can only be executed at a safepoint"); |
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428 int nclasses = SystemDictionary::number_of_classes(); |
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429 double classes_per_tick = nclasses * (CounterDecayMinIntervalLength * 1e-3 / |
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430 CounterHalfLifeTime); |
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431 for (int i = 0; i < classes_per_tick; i++) { |
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432 klassOop k = SystemDictionary::try_get_next_class(); |
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433 if (k != NULL && k->klass_part()->oop_is_instance()) { |
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434 instanceKlass::cast(k)->methods_do(do_method); |
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435 } |
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436 } |
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437 } |
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438 |
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439 // Various cleaning tasks that should be done periodically at safepoints |
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440 void SafepointSynchronize::do_cleanup_tasks() { |
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441 jlong cleanup_time; |
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442 |
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443 // Update fat-monitor pool, since this is a safepoint. |
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444 if (TraceSafepoint) { |
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445 cleanup_time = os::javaTimeNanos(); |
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446 } |
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447 |
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448 ObjectSynchronizer::deflate_idle_monitors(); |
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449 InlineCacheBuffer::update_inline_caches(); |
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450 if(UseCounterDecay && CounterDecay::is_decay_needed()) { |
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451 CounterDecay::decay(); |
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452 } |
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453 NMethodSweeper::sweep(); |
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454 |
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455 if (TraceSafepoint) { |
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456 tty->print_cr("do_cleanup_tasks takes "INT64_FORMAT_W(6) "ms", |
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457 (os::javaTimeNanos() - cleanup_time) / MICROUNITS); |
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458 } |
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459 } |
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460 |
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461 |
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462 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { |
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463 switch(state) { |
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464 case _thread_in_native: |
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465 // native threads are safe if they have no java stack or have walkable stack |
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466 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); |
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467 |
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468 // blocked threads should have already have walkable stack |
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469 case _thread_blocked: |
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470 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); |
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471 return true; |
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472 |
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473 default: |
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474 return false; |
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475 } |
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476 } |
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477 |
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478 |
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479 // ------------------------------------------------------------------------------------------------------- |
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480 // Implementation of Safepoint callback point |
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481 |
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482 void SafepointSynchronize::block(JavaThread *thread) { |
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483 assert(thread != NULL, "thread must be set"); |
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484 assert(thread->is_Java_thread(), "not a Java thread"); |
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485 |
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486 // Threads shouldn't block if they are in the middle of printing, but... |
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487 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); |
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488 |
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489 // Only bail from the block() call if the thread is gone from the |
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490 // thread list; starting to exit should still block. |
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491 if (thread->is_terminated()) { |
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492 // block current thread if we come here from native code when VM is gone |
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493 thread->block_if_vm_exited(); |
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494 |
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495 // otherwise do nothing |
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496 return; |
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497 } |
|
498 |
|
499 JavaThreadState state = thread->thread_state(); |
|
500 thread->frame_anchor()->make_walkable(thread); |
|
501 |
|
502 // Check that we have a valid thread_state at this point |
|
503 switch(state) { |
|
504 case _thread_in_vm_trans: |
|
505 case _thread_in_Java: // From compiled code |
|
506 |
|
507 // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, |
|
508 // we pretend we are still in the VM. |
|
509 thread->set_thread_state(_thread_in_vm); |
|
510 |
|
511 if (is_synchronizing()) { |
|
512 Atomic::inc (&TryingToBlock) ; |
|
513 } |
|
514 |
|
515 // We will always be holding the Safepoint_lock when we are examine the state |
|
516 // of a thread. Hence, the instructions between the Safepoint_lock->lock() and |
|
517 // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code |
|
518 Safepoint_lock->lock_without_safepoint_check(); |
|
519 if (is_synchronizing()) { |
|
520 // Decrement the number of threads to wait for and signal vm thread |
|
521 assert(_waiting_to_block > 0, "sanity check"); |
|
522 _waiting_to_block--; |
|
523 thread->safepoint_state()->set_has_called_back(true); |
|
524 |
|
525 // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread |
|
526 if (_waiting_to_block == 0) { |
|
527 Safepoint_lock->notify_all(); |
|
528 } |
|
529 } |
|
530 |
|
531 // We transition the thread to state _thread_blocked here, but |
|
532 // we can't do our usual check for external suspension and then |
|
533 // self-suspend after the lock_without_safepoint_check() call |
|
534 // below because we are often called during transitions while |
|
535 // we hold different locks. That would leave us suspended while |
|
536 // holding a resource which results in deadlocks. |
|
537 thread->set_thread_state(_thread_blocked); |
|
538 Safepoint_lock->unlock(); |
|
539 |
|
540 // We now try to acquire the threads lock. Since this lock is hold by the VM thread during |
|
541 // the entire safepoint, the threads will all line up here during the safepoint. |
|
542 Threads_lock->lock_without_safepoint_check(); |
|
543 // restore original state. This is important if the thread comes from compiled code, so it |
|
544 // will continue to execute with the _thread_in_Java state. |
|
545 thread->set_thread_state(state); |
|
546 Threads_lock->unlock(); |
|
547 break; |
|
548 |
|
549 case _thread_in_native_trans: |
|
550 case _thread_blocked_trans: |
|
551 case _thread_new_trans: |
|
552 if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { |
|
553 thread->print_thread_state(); |
|
554 fatal("Deadlock in safepoint code. " |
|
555 "Should have called back to the VM before blocking."); |
|
556 } |
|
557 |
|
558 // We transition the thread to state _thread_blocked here, but |
|
559 // we can't do our usual check for external suspension and then |
|
560 // self-suspend after the lock_without_safepoint_check() call |
|
561 // below because we are often called during transitions while |
|
562 // we hold different locks. That would leave us suspended while |
|
563 // holding a resource which results in deadlocks. |
|
564 thread->set_thread_state(_thread_blocked); |
|
565 |
|
566 // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, |
|
567 // the safepoint code might still be waiting for it to block. We need to change the state here, |
|
568 // so it can see that it is at a safepoint. |
|
569 |
|
570 // Block until the safepoint operation is completed. |
|
571 Threads_lock->lock_without_safepoint_check(); |
|
572 |
|
573 // Restore state |
|
574 thread->set_thread_state(state); |
|
575 |
|
576 Threads_lock->unlock(); |
|
577 break; |
|
578 |
|
579 default: |
|
580 fatal1("Illegal threadstate encountered: %d", state); |
|
581 } |
|
582 |
|
583 // Check for pending. async. exceptions or suspends - except if the |
|
584 // thread was blocked inside the VM. has_special_runtime_exit_condition() |
|
585 // is called last since it grabs a lock and we only want to do that when |
|
586 // we must. |
|
587 // |
|
588 // Note: we never deliver an async exception at a polling point as the |
|
589 // compiler may not have an exception handler for it. The polling |
|
590 // code will notice the async and deoptimize and the exception will |
|
591 // be delivered. (Polling at a return point is ok though). Sure is |
|
592 // a lot of bother for a deprecated feature... |
|
593 // |
|
594 // We don't deliver an async exception if the thread state is |
|
595 // _thread_in_native_trans so JNI functions won't be called with |
|
596 // a surprising pending exception. If the thread state is going back to java, |
|
597 // async exception is checked in check_special_condition_for_native_trans(). |
|
598 |
|
599 if (state != _thread_blocked_trans && |
|
600 state != _thread_in_vm_trans && |
|
601 thread->has_special_runtime_exit_condition()) { |
|
602 thread->handle_special_runtime_exit_condition( |
|
603 !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); |
|
604 } |
|
605 } |
|
606 |
|
607 // ------------------------------------------------------------------------------------------------------ |
|
608 // Exception handlers |
|
609 |
|
610 #ifndef PRODUCT |
|
611 #ifdef _LP64 |
|
612 #define PTR_PAD "" |
|
613 #else |
|
614 #define PTR_PAD " " |
|
615 #endif |
|
616 |
|
617 static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) { |
|
618 bool is_oop = newptr ? ((oop)newptr)->is_oop() : false; |
|
619 tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s", |
|
620 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', |
|
621 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); |
|
622 } |
|
623 |
|
624 static void print_longs(jlong oldptr, jlong newptr, bool wasoop) { |
|
625 bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false; |
|
626 tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s", |
|
627 oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!', |
|
628 newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" ")); |
|
629 } |
|
630 |
|
631 #ifdef SPARC |
|
632 static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) { |
|
633 #ifdef _LP64 |
|
634 tty->print_cr("--------+------address-----+------before-----------+-------after----------+"); |
|
635 const int incr = 1; // Increment to skip a long, in units of intptr_t |
|
636 #else |
|
637 tty->print_cr("--------+--address-+------before-----------+-------after----------+"); |
|
638 const int incr = 2; // Increment to skip a long, in units of intptr_t |
|
639 #endif |
|
640 tty->print_cr("---SP---|"); |
|
641 for( int i=0; i<16; i++ ) { |
|
642 tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } |
|
643 tty->print_cr("--------|"); |
|
644 for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) { |
|
645 tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } |
|
646 tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); |
|
647 tty->print_cr("--------|"); |
|
648 tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; |
|
649 tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; |
|
650 tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; |
|
651 tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr; |
|
652 tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp); |
|
653 old_sp += incr; new_sp += incr; was_oops += incr; |
|
654 // Skip the floats |
|
655 tty->print_cr("--Float-|"PTR_FORMAT,new_sp); |
|
656 tty->print_cr("---FP---|"); |
|
657 old_sp += incr*32; new_sp += incr*32; was_oops += incr*32; |
|
658 for( int i2=0; i2<16; i2++ ) { |
|
659 tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); } |
|
660 tty->print_cr(""); |
|
661 } |
|
662 #endif // SPARC |
|
663 #endif // PRODUCT |
|
664 |
|
665 |
|
666 void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { |
|
667 assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); |
|
668 assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); |
|
669 assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); |
|
670 |
|
671 // Uncomment this to get some serious before/after printing of the |
|
672 // Sparc safepoint-blob frame structure. |
|
673 /* |
|
674 intptr_t* sp = thread->last_Java_sp(); |
|
675 intptr_t stack_copy[150]; |
|
676 for( int i=0; i<150; i++ ) stack_copy[i] = sp[i]; |
|
677 bool was_oops[150]; |
|
678 for( int i=0; i<150; i++ ) |
|
679 was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false; |
|
680 */ |
|
681 |
|
682 if (ShowSafepointMsgs) { |
|
683 tty->print("handle_polling_page_exception: "); |
|
684 } |
|
685 |
|
686 if (PrintSafepointStatistics) { |
|
687 inc_page_trap_count(); |
|
688 } |
|
689 |
|
690 ThreadSafepointState* state = thread->safepoint_state(); |
|
691 |
|
692 state->handle_polling_page_exception(); |
|
693 // print_me(sp,stack_copy,was_oops); |
|
694 } |
|
695 |
|
696 |
|
697 void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { |
|
698 if (!timeout_error_printed) { |
|
699 timeout_error_printed = true; |
|
700 // Print out the thread infor which didn't reach the safepoint for debugging |
|
701 // purposes (useful when there are lots of threads in the debugger). |
|
702 tty->print_cr(""); |
|
703 tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); |
|
704 if (reason == _spinning_timeout) { |
|
705 tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); |
|
706 } else if (reason == _blocking_timeout) { |
|
707 tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); |
|
708 } |
|
709 |
|
710 tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); |
|
711 ThreadSafepointState *cur_state; |
|
712 ResourceMark rm; |
|
713 for(JavaThread *cur_thread = Threads::first(); cur_thread; |
|
714 cur_thread = cur_thread->next()) { |
|
715 cur_state = cur_thread->safepoint_state(); |
|
716 |
|
717 if (cur_thread->thread_state() != _thread_blocked && |
|
718 ((reason == _spinning_timeout && cur_state->is_running()) || |
|
719 (reason == _blocking_timeout && !cur_state->has_called_back()))) { |
|
720 tty->print("# "); |
|
721 cur_thread->print(); |
|
722 tty->print_cr(""); |
|
723 } |
|
724 } |
|
725 tty->print_cr("# SafepointSynchronize::begin: (End of list)"); |
|
726 } |
|
727 |
|
728 // To debug the long safepoint, specify both DieOnSafepointTimeout & |
|
729 // ShowMessageBoxOnError. |
|
730 if (DieOnSafepointTimeout) { |
|
731 char msg[1024]; |
|
732 VM_Operation *op = VMThread::vm_operation(); |
|
733 sprintf(msg, "Safepoint sync time longer than %d ms detected when executing %s.", |
|
734 SafepointTimeoutDelay, |
|
735 op != NULL ? op->name() : "no vm operation"); |
|
736 fatal(msg); |
|
737 } |
|
738 } |
|
739 |
|
740 |
|
741 // ------------------------------------------------------------------------------------------------------- |
|
742 // Implementation of ThreadSafepointState |
|
743 |
|
744 ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { |
|
745 _thread = thread; |
|
746 _type = _running; |
|
747 _has_called_back = false; |
|
748 _at_poll_safepoint = false; |
|
749 } |
|
750 |
|
751 void ThreadSafepointState::create(JavaThread *thread) { |
|
752 ThreadSafepointState *state = new ThreadSafepointState(thread); |
|
753 thread->set_safepoint_state(state); |
|
754 } |
|
755 |
|
756 void ThreadSafepointState::destroy(JavaThread *thread) { |
|
757 if (thread->safepoint_state()) { |
|
758 delete(thread->safepoint_state()); |
|
759 thread->set_safepoint_state(NULL); |
|
760 } |
|
761 } |
|
762 |
|
763 void ThreadSafepointState::examine_state_of_thread() { |
|
764 assert(is_running(), "better be running or just have hit safepoint poll"); |
|
765 |
|
766 JavaThreadState state = _thread->thread_state(); |
|
767 |
|
768 // Check for a thread that is suspended. Note that thread resume tries |
|
769 // to grab the Threads_lock which we own here, so a thread cannot be |
|
770 // resumed during safepoint synchronization. |
|
771 |
|
772 // We check with locking because another thread that has not yet |
|
773 // synchronized may be trying to suspend this one. |
|
774 bool is_suspended = _thread->is_any_suspended_with_lock(); |
|
775 if (is_suspended) { |
|
776 roll_forward(_at_safepoint); |
|
777 return; |
|
778 } |
|
779 |
|
780 // Some JavaThread states have an initial safepoint state of |
|
781 // running, but are actually at a safepoint. We will happily |
|
782 // agree and update the safepoint state here. |
|
783 if (SafepointSynchronize::safepoint_safe(_thread, state)) { |
|
784 roll_forward(_at_safepoint); |
|
785 return; |
|
786 } |
|
787 |
|
788 if (state == _thread_in_vm) { |
|
789 roll_forward(_call_back); |
|
790 return; |
|
791 } |
|
792 |
|
793 // All other thread states will continue to run until they |
|
794 // transition and self-block in state _blocked |
|
795 // Safepoint polling in compiled code causes the Java threads to do the same. |
|
796 // Note: new threads may require a malloc so they must be allowed to finish |
|
797 |
|
798 assert(is_running(), "examine_state_of_thread on non-running thread"); |
|
799 return; |
|
800 } |
|
801 |
|
802 // Returns true is thread could not be rolled forward at present position. |
|
803 void ThreadSafepointState::roll_forward(suspend_type type) { |
|
804 _type = type; |
|
805 |
|
806 switch(_type) { |
|
807 case _at_safepoint: |
|
808 SafepointSynchronize::signal_thread_at_safepoint(); |
|
809 break; |
|
810 |
|
811 case _call_back: |
|
812 set_has_called_back(false); |
|
813 break; |
|
814 |
|
815 case _running: |
|
816 default: |
|
817 ShouldNotReachHere(); |
|
818 } |
|
819 } |
|
820 |
|
821 void ThreadSafepointState::restart() { |
|
822 switch(type()) { |
|
823 case _at_safepoint: |
|
824 case _call_back: |
|
825 break; |
|
826 |
|
827 case _running: |
|
828 default: |
|
829 tty->print_cr("restart thread "INTPTR_FORMAT" with state %d", |
|
830 _thread, _type); |
|
831 _thread->print(); |
|
832 ShouldNotReachHere(); |
|
833 } |
|
834 _type = _running; |
|
835 set_has_called_back(false); |
|
836 } |
|
837 |
|
838 |
|
839 void ThreadSafepointState::print_on(outputStream *st) const { |
|
840 const char *s; |
|
841 |
|
842 switch(_type) { |
|
843 case _running : s = "_running"; break; |
|
844 case _at_safepoint : s = "_at_safepoint"; break; |
|
845 case _call_back : s = "_call_back"; break; |
|
846 default: |
|
847 ShouldNotReachHere(); |
|
848 } |
|
849 |
|
850 st->print_cr("Thread: " INTPTR_FORMAT |
|
851 " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", |
|
852 _thread, _thread->osthread()->thread_id(), s, _has_called_back, |
|
853 _at_poll_safepoint); |
|
854 |
|
855 _thread->print_thread_state_on(st); |
|
856 } |
|
857 |
|
858 |
|
859 // --------------------------------------------------------------------------------------------------------------------- |
|
860 |
|
861 // Block the thread at the safepoint poll or poll return. |
|
862 void ThreadSafepointState::handle_polling_page_exception() { |
|
863 |
|
864 // Check state. block() will set thread state to thread_in_vm which will |
|
865 // cause the safepoint state _type to become _call_back. |
|
866 assert(type() == ThreadSafepointState::_running, |
|
867 "polling page exception on thread not running state"); |
|
868 |
|
869 // Step 1: Find the nmethod from the return address |
|
870 if (ShowSafepointMsgs && Verbose) { |
|
871 tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc()); |
|
872 } |
|
873 address real_return_addr = thread()->saved_exception_pc(); |
|
874 |
|
875 CodeBlob *cb = CodeCache::find_blob(real_return_addr); |
|
876 assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod"); |
|
877 nmethod* nm = (nmethod*)cb; |
|
878 |
|
879 // Find frame of caller |
|
880 frame stub_fr = thread()->last_frame(); |
|
881 CodeBlob* stub_cb = stub_fr.cb(); |
|
882 assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); |
|
883 RegisterMap map(thread(), true); |
|
884 frame caller_fr = stub_fr.sender(&map); |
|
885 |
|
886 // Should only be poll_return or poll |
|
887 assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); |
|
888 |
|
889 // This is a poll immediately before a return. The exception handling code |
|
890 // has already had the effect of causing the return to occur, so the execution |
|
891 // will continue immediately after the call. In addition, the oopmap at the |
|
892 // return point does not mark the return value as an oop (if it is), so |
|
893 // it needs a handle here to be updated. |
|
894 if( nm->is_at_poll_return(real_return_addr) ) { |
|
895 // See if return type is an oop. |
|
896 bool return_oop = nm->method()->is_returning_oop(); |
|
897 Handle return_value; |
|
898 if (return_oop) { |
|
899 // The oop result has been saved on the stack together with all |
|
900 // the other registers. In order to preserve it over GCs we need |
|
901 // to keep it in a handle. |
|
902 oop result = caller_fr.saved_oop_result(&map); |
|
903 assert(result == NULL || result->is_oop(), "must be oop"); |
|
904 return_value = Handle(thread(), result); |
|
905 assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); |
|
906 } |
|
907 |
|
908 // Block the thread |
|
909 SafepointSynchronize::block(thread()); |
|
910 |
|
911 // restore oop result, if any |
|
912 if (return_oop) { |
|
913 caller_fr.set_saved_oop_result(&map, return_value()); |
|
914 } |
|
915 } |
|
916 |
|
917 // This is a safepoint poll. Verify the return address and block. |
|
918 else { |
|
919 set_at_poll_safepoint(true); |
|
920 |
|
921 // verify the blob built the "return address" correctly |
|
922 assert(real_return_addr == caller_fr.pc(), "must match"); |
|
923 |
|
924 // Block the thread |
|
925 SafepointSynchronize::block(thread()); |
|
926 set_at_poll_safepoint(false); |
|
927 |
|
928 // If we have a pending async exception deoptimize the frame |
|
929 // as otherwise we may never deliver it. |
|
930 if (thread()->has_async_condition()) { |
|
931 ThreadInVMfromJavaNoAsyncException __tiv(thread()); |
|
932 VM_DeoptimizeFrame deopt(thread(), caller_fr.id()); |
|
933 VMThread::execute(&deopt); |
|
934 } |
|
935 |
|
936 // If an exception has been installed we must check for a pending deoptimization |
|
937 // Deoptimize frame if exception has been thrown. |
|
938 |
|
939 if (thread()->has_pending_exception() ) { |
|
940 RegisterMap map(thread(), true); |
|
941 frame caller_fr = stub_fr.sender(&map); |
|
942 if (caller_fr.is_deoptimized_frame()) { |
|
943 // The exception patch will destroy registers that are still |
|
944 // live and will be needed during deoptimization. Defer the |
|
945 // Async exception should have defered the exception until the |
|
946 // next safepoint which will be detected when we get into |
|
947 // the interpreter so if we have an exception now things |
|
948 // are messed up. |
|
949 |
|
950 fatal("Exception installed and deoptimization is pending"); |
|
951 } |
|
952 } |
|
953 } |
|
954 } |
|
955 |
|
956 |
|
957 // |
|
958 // Statistics & Instrumentations |
|
959 // |
|
960 SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; |
|
961 int SafepointSynchronize::_cur_stat_index = 0; |
|
962 julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; |
|
963 julong SafepointSynchronize::_coalesced_vmop_count = 0; |
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964 jlong SafepointSynchronize::_max_sync_time = 0; |
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965 |
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966 // last_safepoint_start_time records the start time of last safepoint. |
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967 static jlong last_safepoint_start_time = 0; |
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968 static jlong sync_end_time = 0; |
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969 static bool need_to_track_page_armed_status = false; |
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970 static bool init_done = false; |
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971 |
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972 void SafepointSynchronize::deferred_initialize_stat() { |
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973 if (init_done) return; |
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974 |
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975 if (PrintSafepointStatisticsCount <= 0) { |
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976 fatal("Wrong PrintSafepointStatisticsCount"); |
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977 } |
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978 |
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979 // If PrintSafepointStatisticsTimeout is specified, the statistics data will |
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980 // be printed right away, in which case, _safepoint_stats will regress to |
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981 // a single element array. Otherwise, it is a circular ring buffer with default |
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982 // size of PrintSafepointStatisticsCount. |
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983 int stats_array_size; |
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984 if (PrintSafepointStatisticsTimeout > 0) { |
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985 stats_array_size = 1; |
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986 PrintSafepointStatistics = true; |
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987 } else { |
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988 stats_array_size = PrintSafepointStatisticsCount; |
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989 } |
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990 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size |
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991 * sizeof(SafepointStats)); |
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992 guarantee(_safepoint_stats != NULL, |
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993 "not enough memory for safepoint instrumentation data"); |
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994 |
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995 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) { |
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996 need_to_track_page_armed_status = true; |
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997 } |
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998 |
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999 tty->print(" vmop_name " |
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1000 "[threads: total initially_running wait_to_block] "); |
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1001 tty->print("[time: spin block sync] " |
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1002 "[vmop_time time_elapsed] "); |
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1003 |
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1004 // no page armed status printed out if it is always armed. |
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1005 if (need_to_track_page_armed_status) { |
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1006 tty->print("page_armed "); |
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1007 } |
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1008 |
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1009 tty->print_cr("page_trap_count"); |
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1010 |
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1011 init_done = true; |
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1012 } |
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1013 |
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1014 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { |
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1015 deferred_initialize_stat(); |
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1016 |
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1017 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1018 |
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1019 VM_Operation *op = VMThread::vm_operation(); |
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1020 spstat->_vmop_type = (op != NULL ? op->type() : -1); |
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1021 if (op != NULL) { |
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1022 _safepoint_reasons[spstat->_vmop_type]++; |
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1023 } |
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1024 |
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1025 spstat->_nof_total_threads = nof_threads; |
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1026 spstat->_nof_initial_running_threads = nof_running; |
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1027 spstat->_nof_threads_hit_page_trap = 0; |
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1028 |
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1029 // Records the start time of spinning. The real time spent on spinning |
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1030 // will be adjusted when spin is done. Same trick is applied for time |
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1031 // spent on waiting for threads to block. |
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1032 if (nof_running != 0) { |
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1033 spstat->_time_to_spin = os::javaTimeNanos(); |
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1034 } else { |
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1035 spstat->_time_to_spin = 0; |
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1036 } |
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1037 |
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1038 if (last_safepoint_start_time == 0) { |
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1039 spstat->_time_elapsed_since_last_safepoint = 0; |
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1040 } else { |
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1041 spstat->_time_elapsed_since_last_safepoint = _last_safepoint - |
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1042 last_safepoint_start_time; |
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1043 } |
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1044 last_safepoint_start_time = _last_safepoint; |
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1045 } |
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1046 |
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1047 void SafepointSynchronize::update_statistics_on_spin_end() { |
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1048 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1049 |
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1050 jlong cur_time = os::javaTimeNanos(); |
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1051 |
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1052 spstat->_nof_threads_wait_to_block = _waiting_to_block; |
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1053 if (spstat->_nof_initial_running_threads != 0) { |
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1054 spstat->_time_to_spin = cur_time - spstat->_time_to_spin; |
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1055 } |
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1056 |
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1057 if (need_to_track_page_armed_status) { |
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1058 spstat->_page_armed = (PageArmed == 1); |
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1059 } |
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1060 |
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1061 // Records the start time of waiting for to block. Updated when block is done. |
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1062 if (_waiting_to_block != 0) { |
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1063 spstat->_time_to_wait_to_block = cur_time; |
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1064 } else { |
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1065 spstat->_time_to_wait_to_block = 0; |
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1066 } |
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1067 } |
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1068 |
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1069 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { |
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1070 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1071 |
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1072 if (spstat->_nof_threads_wait_to_block != 0) { |
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1073 spstat->_time_to_wait_to_block = end_time - |
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1074 spstat->_time_to_wait_to_block; |
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1075 } |
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1076 |
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1077 // Records the end time of sync which will be used to calculate the total |
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1078 // vm operation time. Again, the real time spending in syncing will be deducted |
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1079 // from the start of the sync time later when end_statistics is called. |
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1080 spstat->_time_to_sync = end_time - _last_safepoint; |
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1081 if (spstat->_time_to_sync > _max_sync_time) { |
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1082 _max_sync_time = spstat->_time_to_sync; |
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1083 } |
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1084 sync_end_time = end_time; |
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1085 } |
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1086 |
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1087 void SafepointSynchronize::end_statistics(jlong vmop_end_time) { |
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1088 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1089 |
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1090 // Update the vm operation time. |
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1091 spstat->_time_to_exec_vmop = vmop_end_time - sync_end_time; |
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1092 // Only the sync time longer than the specified |
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1093 // PrintSafepointStatisticsTimeout will be printed out right away. |
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1094 // By default, it is -1 meaning all samples will be put into the list. |
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1095 if ( PrintSafepointStatisticsTimeout > 0) { |
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1096 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { |
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1097 print_statistics(); |
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1098 } |
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1099 } else { |
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1100 // The safepoint statistics will be printed out when the _safepoin_stats |
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1101 // array fills up. |
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1102 if (_cur_stat_index != PrintSafepointStatisticsCount - 1) { |
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1103 _cur_stat_index ++; |
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1104 } else { |
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1105 print_statistics(); |
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1106 _cur_stat_index = 0; |
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1107 tty->print_cr(""); |
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1108 } |
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1109 } |
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1110 } |
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1111 |
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1112 void SafepointSynchronize::print_statistics() { |
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1113 int index; |
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1114 SafepointStats* sstats = _safepoint_stats; |
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1115 |
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1116 for (index = 0; index <= _cur_stat_index; index++) { |
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1117 sstats = &_safepoint_stats[index]; |
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1118 tty->print("%-28s [" |
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1119 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15) |
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1120 "] ", |
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1121 sstats->_vmop_type == -1 ? "no vm operation" : |
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1122 VM_Operation::name(sstats->_vmop_type), |
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1123 sstats->_nof_total_threads, |
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1124 sstats->_nof_initial_running_threads, |
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1125 sstats->_nof_threads_wait_to_block); |
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1126 // "/ MICROUNITS " is to convert the unit from nanos to millis. |
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1127 tty->print(" [" |
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1128 INT64_FORMAT_W(6)INT64_FORMAT_W(6)INT64_FORMAT_W(6) |
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1129 "] " |
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1130 "["INT64_FORMAT_W(6)INT64_FORMAT_W(9) "] ", |
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1131 sstats->_time_to_spin / MICROUNITS, |
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1132 sstats->_time_to_wait_to_block / MICROUNITS, |
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1133 sstats->_time_to_sync / MICROUNITS, |
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1134 sstats->_time_to_exec_vmop / MICROUNITS, |
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1135 sstats->_time_elapsed_since_last_safepoint / MICROUNITS); |
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1136 |
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1137 if (need_to_track_page_armed_status) { |
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1138 tty->print(INT32_FORMAT" ", sstats->_page_armed); |
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1139 } |
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1140 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap); |
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1141 } |
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1142 } |
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1143 |
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1144 // This method will be called when VM exits. It will first call |
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1145 // print_statistics to print out the rest of the sampling. Then |
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1146 // it tries to summarize the sampling. |
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1147 void SafepointSynchronize::print_stat_on_exit() { |
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1148 if (_safepoint_stats == NULL) return; |
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1149 |
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1150 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
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1151 |
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1152 // During VM exit, end_statistics may not get called and in that |
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1153 // case, if the sync time is less than PrintSafepointStatisticsTimeout, |
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1154 // don't print it out. |
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1155 // Approximate the vm op time. |
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1156 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = |
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1157 os::javaTimeNanos() - sync_end_time; |
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1158 |
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1159 if ( PrintSafepointStatisticsTimeout < 0 || |
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1160 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) { |
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1161 print_statistics(); |
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1162 } |
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1163 tty->print_cr(""); |
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1164 |
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1165 // Print out polling page sampling status. |
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1166 if (!need_to_track_page_armed_status) { |
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1167 if (UseCompilerSafepoints) { |
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1168 tty->print_cr("Polling page always armed"); |
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1169 } |
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1170 } else { |
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1171 tty->print_cr("Defer polling page loop count = %d\n", |
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1172 DeferPollingPageLoopCount); |
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1173 } |
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1174 |
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1175 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { |
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1176 if (_safepoint_reasons[index] != 0) { |
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1177 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index), |
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1178 _safepoint_reasons[index]); |
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1179 } |
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1180 } |
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1181 |
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1182 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint", |
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1183 _coalesced_vmop_count); |
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1184 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms", |
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1185 _max_sync_time / MICROUNITS); |
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1186 } |
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1187 |
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1188 // ------------------------------------------------------------------------------------------------ |
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1189 // Non-product code |
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1190 |
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1191 #ifndef PRODUCT |
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1192 |
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1193 void SafepointSynchronize::print_state() { |
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1194 if (_state == _not_synchronized) { |
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1195 tty->print_cr("not synchronized"); |
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1196 } else if (_state == _synchronizing || _state == _synchronized) { |
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1197 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : |
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1198 "synchronized"); |
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1199 |
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1200 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { |
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1201 cur->safepoint_state()->print(); |
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1202 } |
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1203 } |
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1204 } |
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1205 |
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1206 void SafepointSynchronize::safepoint_msg(const char* format, ...) { |
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1207 if (ShowSafepointMsgs) { |
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1208 va_list ap; |
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1209 va_start(ap, format); |
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1210 tty->vprint_cr(format, ap); |
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1211 va_end(ap); |
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1212 } |
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1213 } |
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1214 |
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1215 #endif // !PRODUCT |