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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
|
|
|
378 // large numbers of threads. Apparently this is due to the synchronous nature
|
|
|
379 // of suspending threads.
|
|
|
380 //
|
|
|
381 // TODO-FIXME: the comments above are vestigial and no longer apply.
|
|
|
382 // Furthermore, using solaris' schedctl in this particular context confers no benefit
|
|
|
383 if (VMThreadHintNoPreempt) {
|
|
|
384 os::hint_no_preempt();
|
|
|
385 }
|
|
|
386 ThreadSafepointState* cur_state = current->safepoint_state();
|
|
|
387 assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
|
|
|
388 cur_state->restart();
|
|
|
389 assert(cur_state->is_running(), "safepoint state has not been reset");
|
|
|
390 }
|
|
|
391
|
|
|
392 RuntimeService::record_safepoint_end();
|
|
|
393
|
|
|
394 // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
|
|
|
395 // blocked in signal_thread_blocked
|
|
|
396 Threads_lock->unlock();
|
|
|
397
|
|
|
398 }
|
|
|
399 #ifndef SERIALGC
|
|
|
400 // If there are any concurrent GC threads resume them.
|
|
|
401 if (UseConcMarkSweepGC) {
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|
|
402 ConcurrentMarkSweepThread::desynchronize(false);
|
|
|
403 } else {
|
|
|
404 ConcurrentGCThread::safepoint_desynchronize();
|
|
|
405 }
|
|
|
406 #endif // SERIALGC
|
|
|
407 }
|
|
|
408
|
|
|
409 bool SafepointSynchronize::is_cleanup_needed() {
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|
|
410 // Need a safepoint if some inline cache buffers is non-empty
|
|
|
411 if (!InlineCacheBuffer::is_empty()) return true;
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|
412 return false;
|
|
|
413 }
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|
|
414
|
|
|
415 jlong CounterDecay::_last_timestamp = 0;
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|
|
416
|
|
|
417 static void do_method(methodOop m) {
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|
|
418 m->invocation_counter()->decay();
|
|
|
419 }
|
|
|
420
|
|
|
421 void CounterDecay::decay() {
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422 _last_timestamp = os::javaTimeMillis();
|
|
|
423
|
|
|
424 // This operation is going to be performed only at the end of a safepoint
|
|
|
425 // and hence GC's will not be going on, all Java mutators are suspended
|
|
|
426 // at this point and hence SystemDictionary_lock is also not needed.
|
|
|
427 assert(SafepointSynchronize::is_at_safepoint(), "can only be executed at a safepoint");
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|
|
428 int nclasses = SystemDictionary::number_of_classes();
|
|
|
429 double classes_per_tick = nclasses * (CounterDecayMinIntervalLength * 1e-3 /
|
|
|
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();
|
|
|
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 }
|
|
|
436 }
|
|
|
437 }
|
|
|
438
|
|
|
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;
|
|
|
442
|
|
|
443 // Update fat-monitor pool, since this is a safepoint.
|
|
|
444 if (TraceSafepoint) {
|
|
|
445 cleanup_time = os::javaTimeNanos();
|
|
|
446 }
|
|
|
447
|
|
|
448 ObjectSynchronizer::deflate_idle_monitors();
|
|
|
449 InlineCacheBuffer::update_inline_caches();
|
|
|
450 if(UseCounterDecay && CounterDecay::is_decay_needed()) {
|
|
|
451 CounterDecay::decay();
|
|
|
452 }
|
|
|
453 NMethodSweeper::sweep();
|
|
|
454
|
|
|
455 if (TraceSafepoint) {
|
|
|
456 tty->print_cr("do_cleanup_tasks takes "INT64_FORMAT_W(6) "ms",
|
|
|
457 (os::javaTimeNanos() - cleanup_time) / MICROUNITS);
|
|
|
458 }
|
|
|
459 }
|
|
|
460
|
|
|
461
|
|
|
462 bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
|
|
|
463 switch(state) {
|
|
|
464 case _thread_in_native:
|
|
|
465 // native threads are safe if they have no java stack or have walkable stack
|
|
|
466 return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
|
|
|
467
|
|
|
468 // blocked threads should have already have walkable stack
|
|
|
469 case _thread_blocked:
|
|
|
470 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
|
|
|
471 return true;
|
|
|
472
|
|
|
473 default:
|
|
|
474 return false;
|
|
|
475 }
|
|
|
476 }
|
|
|
477
|
|
|
478
|
|
|
479 // -------------------------------------------------------------------------------------------------------
|
|
|
480 // Implementation of Safepoint callback point
|
|
|
481
|
|
|
482 void SafepointSynchronize::block(JavaThread *thread) {
|
|
|
483 assert(thread != NULL, "thread must be set");
|
|
|
484 assert(thread->is_Java_thread(), "not a Java thread");
|
|
|
485
|
|
|
486 // Threads shouldn't block if they are in the middle of printing, but...
|
|
|
487 ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
|
|
|
488
|
|
|
489 // Only bail from the block() call if the thread is gone from the
|
|
|
490 // thread list; starting to exit should still block.
|
|
|
491 if (thread->is_terminated()) {
|
|
|
492 // block current thread if we come here from native code when VM is gone
|
|
|
493 thread->block_if_vm_exited();
|
|
|
494
|
|
|
495 // otherwise do nothing
|
|
|
496 return;
|
|
|
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;
|
|
|
964 jlong SafepointSynchronize::_max_sync_time = 0;
|
|
|
965
|
|
|
966 // last_safepoint_start_time records the start time of last safepoint.
|
|
|
967 static jlong last_safepoint_start_time = 0;
|
|
|
968 static jlong sync_end_time = 0;
|
|
|
969 static bool need_to_track_page_armed_status = false;
|
|
|
970 static bool init_done = false;
|
|
|
971
|
|
|
972 void SafepointSynchronize::deferred_initialize_stat() {
|
|
|
973 if (init_done) return;
|
|
|
974
|
|
|
975 if (PrintSafepointStatisticsCount <= 0) {
|
|
|
976 fatal("Wrong PrintSafepointStatisticsCount");
|
|
|
977 }
|
|
|
978
|
|
|
979 // If PrintSafepointStatisticsTimeout is specified, the statistics data will
|
|
|
980 // be printed right away, in which case, _safepoint_stats will regress to
|
|
|
981 // a single element array. Otherwise, it is a circular ring buffer with default
|
|
|
982 // size of PrintSafepointStatisticsCount.
|
|
|
983 int stats_array_size;
|
|
|
984 if (PrintSafepointStatisticsTimeout > 0) {
|
|
|
985 stats_array_size = 1;
|
|
|
986 PrintSafepointStatistics = true;
|
|
|
987 } else {
|
|
|
988 stats_array_size = PrintSafepointStatisticsCount;
|
|
|
989 }
|
|
|
990 _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
|
|
|
991 * sizeof(SafepointStats));
|
|
|
992 guarantee(_safepoint_stats != NULL,
|
|
|
993 "not enough memory for safepoint instrumentation data");
|
|
|
994
|
|
|
995 if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
|
|
|
996 need_to_track_page_armed_status = true;
|
|
|
997 }
|
|
|
998
|
|
|
999 tty->print(" vmop_name "
|
|
|
1000 "[threads: total initially_running wait_to_block] ");
|
|
|
1001 tty->print("[time: spin block sync] "
|
|
|
1002 "[vmop_time time_elapsed] ");
|
|
|
1003
|
|
|
1004 // no page armed status printed out if it is always armed.
|
|
|
1005 if (need_to_track_page_armed_status) {
|
|
|
1006 tty->print("page_armed ");
|
|
|
1007 }
|
|
|
1008
|
|
|
1009 tty->print_cr("page_trap_count");
|
|
|
1010
|
|
|
1011 init_done = true;
|
|
|
1012 }
|
|
|
1013
|
|
|
1014 void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
|
|
|
1015 deferred_initialize_stat();
|
|
|
1016
|
|
|
1017 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
|
1018
|
|
|
1019 VM_Operation *op = VMThread::vm_operation();
|
|
|
1020 spstat->_vmop_type = (op != NULL ? op->type() : -1);
|
|
|
1021 if (op != NULL) {
|
|
|
1022 _safepoint_reasons[spstat->_vmop_type]++;
|
|
|
1023 }
|
|
|
1024
|
|
|
1025 spstat->_nof_total_threads = nof_threads;
|
|
|
1026 spstat->_nof_initial_running_threads = nof_running;
|
|
|
1027 spstat->_nof_threads_hit_page_trap = 0;
|
|
|
1028
|
|
|
1029 // Records the start time of spinning. The real time spent on spinning
|
|
|
1030 // will be adjusted when spin is done. Same trick is applied for time
|
|
|
1031 // spent on waiting for threads to block.
|
|
|
1032 if (nof_running != 0) {
|
|
|
1033 spstat->_time_to_spin = os::javaTimeNanos();
|
|
|
1034 } else {
|
|
|
1035 spstat->_time_to_spin = 0;
|
|
|
1036 }
|
|
|
1037
|
|
|
1038 if (last_safepoint_start_time == 0) {
|
|
|
1039 spstat->_time_elapsed_since_last_safepoint = 0;
|
|
|
1040 } else {
|
|
|
1041 spstat->_time_elapsed_since_last_safepoint = _last_safepoint -
|
|
|
1042 last_safepoint_start_time;
|
|
|
1043 }
|
|
|
1044 last_safepoint_start_time = _last_safepoint;
|
|
|
1045 }
|
|
|
1046
|
|
|
1047 void SafepointSynchronize::update_statistics_on_spin_end() {
|
|
|
1048 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
|
1049
|
|
|
1050 jlong cur_time = os::javaTimeNanos();
|
|
|
1051
|
|
|
1052 spstat->_nof_threads_wait_to_block = _waiting_to_block;
|
|
|
1053 if (spstat->_nof_initial_running_threads != 0) {
|
|
|
1054 spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
|
|
|
1055 }
|
|
|
1056
|
|
|
1057 if (need_to_track_page_armed_status) {
|
|
|
1058 spstat->_page_armed = (PageArmed == 1);
|
|
|
1059 }
|
|
|
1060
|
|
|
1061 // Records the start time of waiting for to block. Updated when block is done.
|
|
|
1062 if (_waiting_to_block != 0) {
|
|
|
1063 spstat->_time_to_wait_to_block = cur_time;
|
|
|
1064 } else {
|
|
|
1065 spstat->_time_to_wait_to_block = 0;
|
|
|
1066 }
|
|
|
1067 }
|
|
|
1068
|
|
|
1069 void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
|
|
|
1070 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
|
1071
|
|
|
1072 if (spstat->_nof_threads_wait_to_block != 0) {
|
|
|
1073 spstat->_time_to_wait_to_block = end_time -
|
|
|
1074 spstat->_time_to_wait_to_block;
|
|
|
1075 }
|
|
|
1076
|
|
|
1077 // Records the end time of sync which will be used to calculate the total
|
|
|
1078 // vm operation time. Again, the real time spending in syncing will be deducted
|
|
|
1079 // from the start of the sync time later when end_statistics is called.
|
|
|
1080 spstat->_time_to_sync = end_time - _last_safepoint;
|
|
|
1081 if (spstat->_time_to_sync > _max_sync_time) {
|
|
|
1082 _max_sync_time = spstat->_time_to_sync;
|
|
|
1083 }
|
|
|
1084 sync_end_time = end_time;
|
|
|
1085 }
|
|
|
1086
|
|
|
1087 void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
|
|
|
1088 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
|
1089
|
|
|
1090 // Update the vm operation time.
|
|
|
1091 spstat->_time_to_exec_vmop = vmop_end_time - sync_end_time;
|
|
|
1092 // Only the sync time longer than the specified
|
|
|
1093 // PrintSafepointStatisticsTimeout will be printed out right away.
|
|
|
1094 // By default, it is -1 meaning all samples will be put into the list.
|
|
|
1095 if ( PrintSafepointStatisticsTimeout > 0) {
|
|
|
1096 if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
|
|
|
1097 print_statistics();
|
|
|
1098 }
|
|
|
1099 } else {
|
|
|
1100 // The safepoint statistics will be printed out when the _safepoin_stats
|
|
|
1101 // array fills up.
|
|
|
1102 if (_cur_stat_index != PrintSafepointStatisticsCount - 1) {
|
|
|
1103 _cur_stat_index ++;
|
|
|
1104 } else {
|
|
|
1105 print_statistics();
|
|
|
1106 _cur_stat_index = 0;
|
|
|
1107 tty->print_cr("");
|
|
|
1108 }
|
|
|
1109 }
|
|
|
1110 }
|
|
|
1111
|
|
|
1112 void SafepointSynchronize::print_statistics() {
|
|
|
1113 int index;
|
|
|
1114 SafepointStats* sstats = _safepoint_stats;
|
|
|
1115
|
|
|
1116 for (index = 0; index <= _cur_stat_index; index++) {
|
|
|
1117 sstats = &_safepoint_stats[index];
|
|
|
1118 tty->print("%-28s ["
|
|
|
1119 INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
|
|
|
1120 "] ",
|
|
|
1121 sstats->_vmop_type == -1 ? "no vm operation" :
|
|
|
1122 VM_Operation::name(sstats->_vmop_type),
|
|
|
1123 sstats->_nof_total_threads,
|
|
|
1124 sstats->_nof_initial_running_threads,
|
|
|
1125 sstats->_nof_threads_wait_to_block);
|
|
|
1126 // "/ MICROUNITS " is to convert the unit from nanos to millis.
|
|
|
1127 tty->print(" ["
|
|
|
1128 INT64_FORMAT_W(6)INT64_FORMAT_W(6)INT64_FORMAT_W(6)
|
|
|
1129 "] "
|
|
|
1130 "["INT64_FORMAT_W(6)INT64_FORMAT_W(9) "] ",
|
|
|
1131 sstats->_time_to_spin / MICROUNITS,
|
|
|
1132 sstats->_time_to_wait_to_block / MICROUNITS,
|
|
|
1133 sstats->_time_to_sync / MICROUNITS,
|
|
|
1134 sstats->_time_to_exec_vmop / MICROUNITS,
|
|
|
1135 sstats->_time_elapsed_since_last_safepoint / MICROUNITS);
|
|
|
1136
|
|
|
1137 if (need_to_track_page_armed_status) {
|
|
|
1138 tty->print(INT32_FORMAT" ", sstats->_page_armed);
|
|
|
1139 }
|
|
|
1140 tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
|
|
|
1141 }
|
|
|
1142 }
|
|
|
1143
|
|
|
1144 // This method will be called when VM exits. It will first call
|
|
|
1145 // print_statistics to print out the rest of the sampling. Then
|
|
|
1146 // it tries to summarize the sampling.
|
|
|
1147 void SafepointSynchronize::print_stat_on_exit() {
|
|
|
1148 if (_safepoint_stats == NULL) return;
|
|
|
1149
|
|
|
1150 SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
|
1151
|
|
|
1152 // During VM exit, end_statistics may not get called and in that
|
|
|
1153 // case, if the sync time is less than PrintSafepointStatisticsTimeout,
|
|
|
1154 // don't print it out.
|
|
|
1155 // Approximate the vm op time.
|
|
|
1156 _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
|
|
|
1157 os::javaTimeNanos() - sync_end_time;
|
|
|
1158
|
|
|
1159 if ( PrintSafepointStatisticsTimeout < 0 ||
|
|
|
1160 spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
|
|
|
1161 print_statistics();
|
|
|
1162 }
|
|
|
1163 tty->print_cr("");
|
|
|
1164
|
|
|
1165 // Print out polling page sampling status.
|
|
|
1166 if (!need_to_track_page_armed_status) {
|
|
|
1167 if (UseCompilerSafepoints) {
|
|
|
1168 tty->print_cr("Polling page always armed");
|
|
|
1169 }
|
|
|
1170 } else {
|
|
|
1171 tty->print_cr("Defer polling page loop count = %d\n",
|
|
|
1172 DeferPollingPageLoopCount);
|
|
|
1173 }
|
|
|
1174
|
|
|
1175 for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
|
|
|
1176 if (_safepoint_reasons[index] != 0) {
|
|
|
1177 tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
|
|
|
1178 _safepoint_reasons[index]);
|
|
|
1179 }
|
|
|
1180 }
|
|
|
1181
|
|
|
1182 tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
|
|
|
1183 _coalesced_vmop_count);
|
|
|
1184 tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
|
|
|
1185 _max_sync_time / MICROUNITS);
|
|
|
1186 }
|
|
|
1187
|
|
|
1188 // ------------------------------------------------------------------------------------------------
|
|
|
1189 // Non-product code
|
|
|
1190
|
|
|
1191 #ifndef PRODUCT
|
|
|
1192
|
|
|
1193 void SafepointSynchronize::print_state() {
|
|
|
1194 if (_state == _not_synchronized) {
|
|
|
1195 tty->print_cr("not synchronized");
|
|
|
1196 } else if (_state == _synchronizing || _state == _synchronized) {
|
|
|
1197 tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
|
|
|
1198 "synchronized");
|
|
|
1199
|
|
|
1200 for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
|
|
|
1201 cur->safepoint_state()->print();
|
|
|
1202 }
|
|
|
1203 }
|
|
|
1204 }
|
|
|
1205
|
|
|
1206 void SafepointSynchronize::safepoint_msg(const char* format, ...) {
|
|
|
1207 if (ShowSafepointMsgs) {
|
|
|
1208 va_list ap;
|
|
|
1209 va_start(ap, format);
|
|
|
1210 tty->vprint_cr(format, ap);
|
|
|
1211 va_end(ap);
|
|
|
1212 }
|
|
|
1213 }
|
|
|
1214
|
|
|
1215 #endif // !PRODUCT
|
