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1 /*
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2 * Copyright 2001-2007 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/_workgroup.cpp.incl"
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27
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28 // Definitions of WorkGang methods.
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29
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30 AbstractWorkGang::AbstractWorkGang(const char* name,
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342
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31 bool are_GC_task_threads,
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32 bool are_ConcurrentGC_threads) :
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33 _name(name),
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342
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34 _are_GC_task_threads(are_GC_task_threads),
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35 _are_ConcurrentGC_threads(are_ConcurrentGC_threads) {
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36
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37 assert(!(are_GC_task_threads && are_ConcurrentGC_threads),
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38 "They cannot both be STW GC and Concurrent threads" );
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39
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0
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40 // Other initialization.
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41 _monitor = new Monitor(/* priority */ Mutex::leaf,
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42 /* name */ "WorkGroup monitor",
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342
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43 /* allow_vm_block */ are_GC_task_threads);
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0
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44 assert(monitor() != NULL, "Failed to allocate monitor");
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45 _terminate = false;
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46 _task = NULL;
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47 _sequence_number = 0;
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48 _started_workers = 0;
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49 _finished_workers = 0;
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50 }
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51
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52 WorkGang::WorkGang(const char* name,
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342
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53 int workers,
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54 bool are_GC_task_threads,
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55 bool are_ConcurrentGC_threads) :
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56 AbstractWorkGang(name, are_GC_task_threads, are_ConcurrentGC_threads)
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57 {
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0
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58 // Save arguments.
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59 _total_workers = workers;
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342
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60
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61 if (TraceWorkGang) {
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62 tty->print_cr("Constructing work gang %s with %d threads", name, workers);
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63 }
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64 _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, workers);
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342
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65 if (gang_workers() == NULL) {
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66 vm_exit_out_of_memory(0, "Cannot create GangWorker array.");
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67 }
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0
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68 for (int worker = 0; worker < total_workers(); worker += 1) {
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69 GangWorker* new_worker = new GangWorker(this, worker);
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70 assert(new_worker != NULL, "Failed to allocate GangWorker");
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71 _gang_workers[worker] = new_worker;
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72 if (new_worker == NULL || !os::create_thread(new_worker, os::pgc_thread))
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73 vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources.");
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74 if (!DisableStartThread) {
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75 os::start_thread(new_worker);
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76 }
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77 }
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78 }
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79
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80 AbstractWorkGang::~AbstractWorkGang() {
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81 if (TraceWorkGang) {
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82 tty->print_cr("Destructing work gang %s", name());
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83 }
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84 stop(); // stop all the workers
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85 for (int worker = 0; worker < total_workers(); worker += 1) {
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86 delete gang_worker(worker);
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87 }
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88 delete gang_workers();
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89 delete monitor();
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90 }
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91
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92 GangWorker* AbstractWorkGang::gang_worker(int i) const {
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93 // Array index bounds checking.
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94 GangWorker* result = NULL;
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95 assert(gang_workers() != NULL, "No workers for indexing");
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96 assert(((i >= 0) && (i < total_workers())), "Worker index out of bounds");
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97 result = _gang_workers[i];
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98 assert(result != NULL, "Indexing to null worker");
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99 return result;
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100 }
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101
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102 void WorkGang::run_task(AbstractGangTask* task) {
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103 // This thread is executed by the VM thread which does not block
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104 // on ordinary MutexLocker's.
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105 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
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106 if (TraceWorkGang) {
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107 tty->print_cr("Running work gang %s task %s", name(), task->name());
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108 }
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109 // Tell all the workers to run a task.
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110 assert(task != NULL, "Running a null task");
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111 // Initialize.
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112 _task = task;
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113 _sequence_number += 1;
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114 _started_workers = 0;
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115 _finished_workers = 0;
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116 // Tell the workers to get to work.
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117 monitor()->notify_all();
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118 // Wait for them to be finished
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119 while (finished_workers() < total_workers()) {
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120 if (TraceWorkGang) {
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121 tty->print_cr("Waiting in work gang %s: %d/%d finished sequence %d",
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122 name(), finished_workers(), total_workers(),
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123 _sequence_number);
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124 }
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125 monitor()->wait(/* no_safepoint_check */ true);
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126 }
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127 _task = NULL;
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128 if (TraceWorkGang) {
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129 tty->print_cr("/nFinished work gang %s: %d/%d sequence %d",
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130 name(), finished_workers(), total_workers(),
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131 _sequence_number);
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132 }
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133 }
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134
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135 void AbstractWorkGang::stop() {
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136 // Tell all workers to terminate, then wait for them to become inactive.
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137 MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
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138 if (TraceWorkGang) {
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139 tty->print_cr("Stopping work gang %s task %s", name(), task()->name());
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140 }
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141 _task = NULL;
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142 _terminate = true;
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143 monitor()->notify_all();
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144 while (finished_workers() < total_workers()) {
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145 if (TraceWorkGang) {
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146 tty->print_cr("Waiting in work gang %s: %d/%d finished",
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147 name(), finished_workers(), total_workers());
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148 }
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149 monitor()->wait(/* no_safepoint_check */ true);
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150 }
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151 }
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152
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153 void AbstractWorkGang::internal_worker_poll(WorkData* data) const {
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154 assert(monitor()->owned_by_self(), "worker_poll is an internal method");
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155 assert(data != NULL, "worker data is null");
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156 data->set_terminate(terminate());
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157 data->set_task(task());
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158 data->set_sequence_number(sequence_number());
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159 }
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160
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161 void AbstractWorkGang::internal_note_start() {
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162 assert(monitor()->owned_by_self(), "note_finish is an internal method");
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163 _started_workers += 1;
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164 }
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165
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166 void AbstractWorkGang::internal_note_finish() {
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167 assert(monitor()->owned_by_self(), "note_finish is an internal method");
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168 _finished_workers += 1;
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169 }
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170
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171 void AbstractWorkGang::print_worker_threads_on(outputStream* st) const {
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172 uint num_thr = total_workers();
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173 for (uint i = 0; i < num_thr; i++) {
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174 gang_worker(i)->print_on(st);
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175 st->cr();
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176 }
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177 }
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178
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179 void AbstractWorkGang::threads_do(ThreadClosure* tc) const {
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180 assert(tc != NULL, "Null ThreadClosure");
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181 uint num_thr = total_workers();
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182 for (uint i = 0; i < num_thr; i++) {
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183 tc->do_thread(gang_worker(i));
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184 }
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185 }
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186
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187 // GangWorker methods.
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188
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189 GangWorker::GangWorker(AbstractWorkGang* gang, uint id) {
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190 _gang = gang;
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191 set_id(id);
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192 set_name("Gang worker#%d (%s)", id, gang->name());
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193 }
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194
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195 void GangWorker::run() {
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196 initialize();
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197 loop();
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198 }
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199
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200 void GangWorker::initialize() {
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201 this->initialize_thread_local_storage();
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202 assert(_gang != NULL, "No gang to run in");
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203 os::set_priority(this, NearMaxPriority);
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204 if (TraceWorkGang) {
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205 tty->print_cr("Running gang worker for gang %s id %d",
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206 gang()->name(), id());
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207 }
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208 // The VM thread should not execute here because MutexLocker's are used
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209 // as (opposed to MutexLockerEx's).
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210 assert(!Thread::current()->is_VM_thread(), "VM thread should not be part"
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211 " of a work gang");
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212 }
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213
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214 void GangWorker::loop() {
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215 int previous_sequence_number = 0;
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216 Monitor* gang_monitor = gang()->monitor();
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217 for ( ; /* !terminate() */; ) {
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218 WorkData data;
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219 int part; // Initialized below.
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220 {
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221 // Grab the gang mutex.
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222 MutexLocker ml(gang_monitor);
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223 // Wait for something to do.
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224 // Polling outside the while { wait } avoids missed notifies
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225 // in the outer loop.
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226 gang()->internal_worker_poll(&data);
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227 if (TraceWorkGang) {
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228 tty->print("Polled outside for work in gang %s worker %d",
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229 gang()->name(), id());
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230 tty->print(" terminate: %s",
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231 data.terminate() ? "true" : "false");
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232 tty->print(" sequence: %d (prev: %d)",
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233 data.sequence_number(), previous_sequence_number);
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234 if (data.task() != NULL) {
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235 tty->print(" task: %s", data.task()->name());
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236 } else {
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237 tty->print(" task: NULL");
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238 }
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239 tty->cr();
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240 }
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241 for ( ; /* break or return */; ) {
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242 // Terminate if requested.
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243 if (data.terminate()) {
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244 gang()->internal_note_finish();
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245 gang_monitor->notify_all();
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246 return;
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247 }
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248 // Check for new work.
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249 if ((data.task() != NULL) &&
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250 (data.sequence_number() != previous_sequence_number)) {
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251 gang()->internal_note_start();
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252 gang_monitor->notify_all();
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253 part = gang()->started_workers() - 1;
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254 break;
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255 }
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256 // Nothing to do.
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257 gang_monitor->wait(/* no_safepoint_check */ true);
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258 gang()->internal_worker_poll(&data);
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259 if (TraceWorkGang) {
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260 tty->print("Polled inside for work in gang %s worker %d",
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261 gang()->name(), id());
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262 tty->print(" terminate: %s",
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263 data.terminate() ? "true" : "false");
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264 tty->print(" sequence: %d (prev: %d)",
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265 data.sequence_number(), previous_sequence_number);
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266 if (data.task() != NULL) {
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267 tty->print(" task: %s", data.task()->name());
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268 } else {
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269 tty->print(" task: NULL");
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270 }
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271 tty->cr();
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272 }
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273 }
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274 // Drop gang mutex.
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275 }
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276 if (TraceWorkGang) {
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277 tty->print("Work for work gang %s id %d task %s part %d",
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278 gang()->name(), id(), data.task()->name(), part);
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279 }
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280 assert(data.task() != NULL, "Got null task");
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281 data.task()->work(part);
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282 {
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283 if (TraceWorkGang) {
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284 tty->print("Finish for work gang %s id %d task %s part %d",
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285 gang()->name(), id(), data.task()->name(), part);
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286 }
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287 // Grab the gang mutex.
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288 MutexLocker ml(gang_monitor);
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289 gang()->internal_note_finish();
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290 // Tell the gang you are done.
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291 gang_monitor->notify_all();
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292 // Drop the gang mutex.
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293 }
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294 previous_sequence_number = data.sequence_number();
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295 }
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296 }
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297
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298 bool GangWorker::is_GC_task_thread() const {
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342
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299 return gang()->are_GC_task_threads();
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300 }
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301
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302 bool GangWorker::is_ConcurrentGC_thread() const {
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303 return gang()->are_ConcurrentGC_threads();
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0
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304 }
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305
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306 void GangWorker::print_on(outputStream* st) const {
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307 st->print("\"%s\" ", name());
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308 Thread::print_on(st);
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309 st->cr();
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310 }
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311
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312 // Printing methods
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313
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314 const char* AbstractWorkGang::name() const {
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315 return _name;
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316 }
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317
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318 #ifndef PRODUCT
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319
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320 const char* AbstractGangTask::name() const {
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321 return _name;
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322 }
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323
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324 #endif /* PRODUCT */
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325
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326 // *** WorkGangBarrierSync
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327
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328 WorkGangBarrierSync::WorkGangBarrierSync()
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329 : _monitor(Mutex::safepoint, "work gang barrier sync", true),
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342
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330 _n_workers(0), _n_completed(0), _should_reset(false) {
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0
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331 }
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332
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333 WorkGangBarrierSync::WorkGangBarrierSync(int n_workers, const char* name)
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334 : _monitor(Mutex::safepoint, name, true),
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342
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335 _n_workers(n_workers), _n_completed(0), _should_reset(false) {
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0
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336 }
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337
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338 void WorkGangBarrierSync::set_n_workers(int n_workers) {
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339 _n_workers = n_workers;
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340 _n_completed = 0;
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342
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341 _should_reset = false;
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0
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342 }
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343
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344 void WorkGangBarrierSync::enter() {
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345 MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag);
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342
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346 if (should_reset()) {
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347 // The should_reset() was set and we are the first worker to enter
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348 // the sync barrier. We will zero the n_completed() count which
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349 // effectively resets the barrier.
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350 zero_completed();
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351 set_should_reset(false);
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352 }
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0
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353 inc_completed();
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354 if (n_completed() == n_workers()) {
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342
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355 // At this point we would like to reset the barrier to be ready in
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356 // case it is used again. However, we cannot set n_completed() to
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357 // 0, even after the notify_all(), given that some other workers
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358 // might still be waiting for n_completed() to become ==
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359 // n_workers(). So, if we set n_completed() to 0, those workers
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360 // will get stuck (as they will wake up, see that n_completed() !=
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361 // n_workers() and go back to sleep). Instead, we raise the
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362 // should_reset() flag and the barrier will be reset the first
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363 // time a worker enters it again.
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364 set_should_reset(true);
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0
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365 monitor()->notify_all();
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342
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366 } else {
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0
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367 while (n_completed() != n_workers()) {
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368 monitor()->wait(/* no_safepoint_check */ true);
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369 }
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370 }
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371 }
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372
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373 // SubTasksDone functions.
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374
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375 SubTasksDone::SubTasksDone(int n) :
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376 _n_tasks(n), _n_threads(1), _tasks(NULL) {
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377 _tasks = NEW_C_HEAP_ARRAY(jint, n);
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378 guarantee(_tasks != NULL, "alloc failure");
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379 clear();
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380 }
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381
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382 bool SubTasksDone::valid() {
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383 return _tasks != NULL;
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384 }
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385
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386 void SubTasksDone::set_par_threads(int t) {
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387 #ifdef ASSERT
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388 assert(_claimed == 0 || _threads_completed == _n_threads,
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389 "should not be called while tasks are being processed!");
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390 #endif
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391 _n_threads = (t == 0 ? 1 : t);
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392 }
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393
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394 void SubTasksDone::clear() {
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395 for (int i = 0; i < _n_tasks; i++) {
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396 _tasks[i] = 0;
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397 }
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398 _threads_completed = 0;
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399 #ifdef ASSERT
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400 _claimed = 0;
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401 #endif
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402 }
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403
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404 bool SubTasksDone::is_task_claimed(int t) {
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405 assert(0 <= t && t < _n_tasks, "bad task id.");
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406 jint old = _tasks[t];
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407 if (old == 0) {
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408 old = Atomic::cmpxchg(1, &_tasks[t], 0);
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409 }
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410 assert(_tasks[t] == 1, "What else?");
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411 bool res = old != 0;
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412 #ifdef ASSERT
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413 if (!res) {
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414 assert(_claimed < _n_tasks, "Too many tasks claimed; missing clear?");
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415 Atomic::inc(&_claimed);
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416 }
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417 #endif
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418 return res;
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419 }
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420
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421 void SubTasksDone::all_tasks_completed() {
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422 jint observed = _threads_completed;
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423 jint old;
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424 do {
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425 old = observed;
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426 observed = Atomic::cmpxchg(old+1, &_threads_completed, old);
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427 } while (observed != old);
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428 // If this was the last thread checking in, clear the tasks.
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429 if (observed+1 == _n_threads) clear();
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430 }
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431
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432
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433 SubTasksDone::~SubTasksDone() {
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434 if (_tasks != NULL) FREE_C_HEAP_ARRAY(jint, _tasks);
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435 }
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436
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437 // *** SequentialSubTasksDone
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438
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439 void SequentialSubTasksDone::clear() {
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440 _n_tasks = _n_claimed = 0;
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441 _n_threads = _n_completed = 0;
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442 }
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443
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444 bool SequentialSubTasksDone::valid() {
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445 return _n_threads > 0;
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446 }
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447
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448 bool SequentialSubTasksDone::is_task_claimed(int& t) {
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449 jint* n_claimed_ptr = &_n_claimed;
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450 t = *n_claimed_ptr;
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451 while (t < _n_tasks) {
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452 jint res = Atomic::cmpxchg(t+1, n_claimed_ptr, t);
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453 if (res == t) {
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454 return false;
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455 }
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456 t = *n_claimed_ptr;
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457 }
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458 return true;
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459 }
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460
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461 bool SequentialSubTasksDone::all_tasks_completed() {
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462 jint* n_completed_ptr = &_n_completed;
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463 jint complete = *n_completed_ptr;
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464 while (true) {
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465 jint res = Atomic::cmpxchg(complete+1, n_completed_ptr, complete);
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466 if (res == complete) {
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467 break;
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468 }
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469 complete = res;
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470 }
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471 if (complete+1 == _n_threads) {
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472 clear();
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473 return true;
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474 }
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475 return false;
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476 }
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342
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477
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478 bool FreeIdSet::_stat_init = false;
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479 FreeIdSet* FreeIdSet::_sets[NSets];
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480 bool FreeIdSet::_safepoint;
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481
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482 FreeIdSet::FreeIdSet(int sz, Monitor* mon) :
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483 _sz(sz), _mon(mon), _hd(0), _waiters(0), _index(-1), _claimed(0)
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484 {
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485 _ids = new int[sz];
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486 for (int i = 0; i < sz; i++) _ids[i] = i+1;
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487 _ids[sz-1] = end_of_list; // end of list.
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488 if (_stat_init) {
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489 for (int j = 0; j < NSets; j++) _sets[j] = NULL;
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490 _stat_init = true;
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491 }
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|
492 // Add to sets. (This should happen while the system is still single-threaded.)
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493 for (int j = 0; j < NSets; j++) {
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494 if (_sets[j] == NULL) {
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|
495 _sets[j] = this;
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|
496 _index = j;
|
|
|
497 break;
|
|
|
498 }
|
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|
499 }
|
|
|
500 guarantee(_index != -1, "Too many FreeIdSets in use!");
|
|
|
501 }
|
|
|
502
|
|
|
503 FreeIdSet::~FreeIdSet() {
|
|
|
504 _sets[_index] = NULL;
|
|
|
505 }
|
|
|
506
|
|
|
507 void FreeIdSet::set_safepoint(bool b) {
|
|
|
508 _safepoint = b;
|
|
|
509 if (b) {
|
|
|
510 for (int j = 0; j < NSets; j++) {
|
|
|
511 if (_sets[j] != NULL && _sets[j]->_waiters > 0) {
|
|
|
512 Monitor* mon = _sets[j]->_mon;
|
|
|
513 mon->lock_without_safepoint_check();
|
|
|
514 mon->notify_all();
|
|
|
515 mon->unlock();
|
|
|
516 }
|
|
|
517 }
|
|
|
518 }
|
|
|
519 }
|
|
|
520
|
|
|
521 #define FID_STATS 0
|
|
|
522
|
|
|
523 int FreeIdSet::claim_par_id() {
|
|
|
524 #if FID_STATS
|
|
|
525 thread_t tslf = thr_self();
|
|
|
526 tty->print("claim_par_id[%d]: sz = %d, claimed = %d\n", tslf, _sz, _claimed);
|
|
|
527 #endif
|
|
|
528 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
|
|
|
529 while (!_safepoint && _hd == end_of_list) {
|
|
|
530 _waiters++;
|
|
|
531 #if FID_STATS
|
|
|
532 if (_waiters > 5) {
|
|
|
533 tty->print("claim_par_id waiting[%d]: %d waiters, %d claimed.\n",
|
|
|
534 tslf, _waiters, _claimed);
|
|
|
535 }
|
|
|
536 #endif
|
|
|
537 _mon->wait(Mutex::_no_safepoint_check_flag);
|
|
|
538 _waiters--;
|
|
|
539 }
|
|
|
540 if (_hd == end_of_list) {
|
|
|
541 #if FID_STATS
|
|
|
542 tty->print("claim_par_id[%d]: returning EOL.\n", tslf);
|
|
|
543 #endif
|
|
|
544 return -1;
|
|
|
545 } else {
|
|
|
546 int res = _hd;
|
|
|
547 _hd = _ids[res];
|
|
|
548 _ids[res] = claimed; // For debugging.
|
|
|
549 _claimed++;
|
|
|
550 #if FID_STATS
|
|
|
551 tty->print("claim_par_id[%d]: returning %d, claimed = %d.\n",
|
|
|
552 tslf, res, _claimed);
|
|
|
553 #endif
|
|
|
554 return res;
|
|
|
555 }
|
|
|
556 }
|
|
|
557
|
|
|
558 bool FreeIdSet::claim_perm_id(int i) {
|
|
|
559 assert(0 <= i && i < _sz, "Out of range.");
|
|
|
560 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
|
|
|
561 int prev = end_of_list;
|
|
|
562 int cur = _hd;
|
|
|
563 while (cur != end_of_list) {
|
|
|
564 if (cur == i) {
|
|
|
565 if (prev == end_of_list) {
|
|
|
566 _hd = _ids[cur];
|
|
|
567 } else {
|
|
|
568 _ids[prev] = _ids[cur];
|
|
|
569 }
|
|
|
570 _ids[cur] = claimed;
|
|
|
571 _claimed++;
|
|
|
572 return true;
|
|
|
573 } else {
|
|
|
574 prev = cur;
|
|
|
575 cur = _ids[cur];
|
|
|
576 }
|
|
|
577 }
|
|
|
578 return false;
|
|
|
579
|
|
|
580 }
|
|
|
581
|
|
|
582 void FreeIdSet::release_par_id(int id) {
|
|
|
583 MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
|
|
|
584 assert(_ids[id] == claimed, "Precondition.");
|
|
|
585 _ids[id] = _hd;
|
|
|
586 _hd = id;
|
|
|
587 _claimed--;
|
|
|
588 #if FID_STATS
|
|
|
589 tty->print("[%d] release_par_id(%d), waiters =%d, claimed = %d.\n",
|
|
|
590 thr_self(), id, _waiters, _claimed);
|
|
|
591 #endif
|
|
|
592 if (_waiters > 0)
|
|
|
593 // Notify all would be safer, but this is OK, right?
|
|
|
594 _mon->notify_all();
|
|
|
595 }
|
