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annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp @ 1972:f95d63e2154a
6989984: Use standard include model for Hospot
Summary: Replaced MakeDeps and the includeDB files with more standardized solutions.
Reviewed-by: coleenp, kvn, kamg
| author | stefank |
|---|---|
| date | Tue, 23 Nov 2010 13:22:55 -0800 |
| parents | cd3ef3fd20dd |
| children | a181f3a124dd |
| rev | line source |
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| 0 | 1 /* |
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2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPTHREAD_HPP |
| 26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPTHREAD_HPP | |
| 27 | |
| 28 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp" | |
| 29 #include "gc_implementation/shared/concurrentGCThread.hpp" | |
| 30 #ifdef TARGET_OS_FAMILY_linux | |
| 31 # include "thread_linux.inline.hpp" | |
| 32 #endif | |
| 33 #ifdef TARGET_OS_FAMILY_solaris | |
| 34 # include "thread_solaris.inline.hpp" | |
| 35 #endif | |
| 36 #ifdef TARGET_OS_FAMILY_windows | |
| 37 # include "thread_windows.inline.hpp" | |
| 38 #endif | |
| 39 | |
| 0 | 40 class ConcurrentMarkSweepGeneration; |
| 41 class CMSCollector; | |
| 42 | |
| 43 // The Concurrent Mark Sweep GC Thread (could be several in the future). | |
| 44 class ConcurrentMarkSweepThread: public ConcurrentGCThread { | |
| 45 friend class VMStructs; | |
| 46 friend class ConcurrentMarkSweepGeneration; // XXX should remove friendship | |
| 47 friend class CMSCollector; | |
| 48 public: | |
| 49 virtual void run(); | |
| 50 | |
| 51 private: | |
| 52 static ConcurrentMarkSweepThread* _cmst; | |
| 53 static CMSCollector* _collector; | |
| 54 static SurrogateLockerThread* _slt; | |
| 55 static SurrogateLockerThread::SLT_msg_type _sltBuffer; | |
| 56 static Monitor* _sltMonitor; | |
| 57 | |
| 58 ConcurrentMarkSweepThread* _next; | |
| 59 | |
| 60 static bool _should_terminate; | |
| 61 | |
| 62 enum CMS_flag_type { | |
| 63 CMS_nil = NoBits, | |
| 64 CMS_cms_wants_token = nth_bit(0), | |
| 65 CMS_cms_has_token = nth_bit(1), | |
| 66 CMS_vm_wants_token = nth_bit(2), | |
| 67 CMS_vm_has_token = nth_bit(3) | |
| 68 }; | |
| 69 | |
| 70 static int _CMS_flag; | |
| 71 | |
| 72 static bool CMS_flag_is_set(int b) { return (_CMS_flag & b) != 0; } | |
| 73 static bool set_CMS_flag(int b) { return (_CMS_flag |= b) != 0; } | |
| 74 static bool clear_CMS_flag(int b) { return (_CMS_flag &= ~b) != 0; } | |
| 75 void sleepBeforeNextCycle(); | |
| 76 | |
| 77 // CMS thread should yield for a young gen collection, direct allocation, | |
| 78 // and iCMS activity. | |
| 79 static char _pad_1[64 - sizeof(jint)]; // prevent cache-line sharing | |
| 80 static volatile jint _pending_yields; | |
| 81 static volatile jint _pending_decrements; // decrements to _pending_yields | |
| 82 static char _pad_2[64 - sizeof(jint)]; // prevent cache-line sharing | |
| 83 | |
| 84 // Tracing messages, enabled by CMSTraceThreadState. | |
| 85 static inline void trace_state(const char* desc); | |
| 86 | |
| 87 static volatile bool _icms_enabled; // iCMS enabled? | |
| 88 static volatile bool _should_run; // iCMS may run | |
| 89 static volatile bool _should_stop; // iCMS should stop | |
| 90 | |
| 91 // debugging | |
| 92 void verify_ok_to_terminate() const PRODUCT_RETURN; | |
| 93 | |
| 94 public: | |
| 95 // Constructor | |
| 96 ConcurrentMarkSweepThread(CMSCollector* collector); | |
| 97 | |
| 98 static void makeSurrogateLockerThread(TRAPS); | |
| 99 static SurrogateLockerThread* slt() { return _slt; } | |
| 100 | |
| 101 // Tester | |
| 102 bool is_ConcurrentGC_thread() const { return true; } | |
| 103 | |
| 104 static void threads_do(ThreadClosure* tc); | |
| 105 | |
| 106 // Printing | |
| 107 void print_on(outputStream* st) const; | |
| 108 void print() const { print_on(tty); } | |
| 109 static void print_all_on(outputStream* st); | |
| 110 static void print_all() { print_all_on(tty); } | |
| 111 | |
| 112 // Returns the CMS Thread | |
| 113 static ConcurrentMarkSweepThread* cmst() { return _cmst; } | |
| 114 static CMSCollector* collector() { return _collector; } | |
| 115 | |
| 116 // Create and start the CMS Thread, or stop it on shutdown | |
| 117 static ConcurrentMarkSweepThread* start(CMSCollector* collector); | |
| 118 static void stop(); | |
| 119 static bool should_terminate() { return _should_terminate; } | |
| 120 | |
| 121 // Synchronization using CMS token | |
| 122 static void synchronize(bool is_cms_thread); | |
| 123 static void desynchronize(bool is_cms_thread); | |
| 124 static bool vm_thread_has_cms_token() { | |
| 125 return CMS_flag_is_set(CMS_vm_has_token); | |
| 126 } | |
| 127 static bool cms_thread_has_cms_token() { | |
| 128 return CMS_flag_is_set(CMS_cms_has_token); | |
| 129 } | |
| 130 static bool vm_thread_wants_cms_token() { | |
| 131 return CMS_flag_is_set(CMS_vm_wants_token); | |
| 132 } | |
| 133 static bool cms_thread_wants_cms_token() { | |
| 134 return CMS_flag_is_set(CMS_cms_wants_token); | |
| 135 } | |
| 136 | |
| 137 // Wait on CMS lock until the next synchronous GC | |
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138 // or given timeout, whichever is earlier. A timeout value |
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139 // of 0 indicates that there is no upper bound on the wait time. |
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140 // A concurrent full gc request terminates the wait. |
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141 void wait_on_cms_lock(long t_millis); |
| 0 | 142 |
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143 // The CMS thread will yield during the work portion of its cycle |
| 0 | 144 // only when requested to. Both synchronous and asychronous requests |
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145 // are provided: |
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146 // (1) A synchronous request is used for young gen collections and |
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147 // for direct allocations. The requesting thread increments |
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148 // _pending_yields at the beginning of an operation, and decrements |
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149 // _pending_yields when that operation is completed. |
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150 // In turn, the CMS thread yields when _pending_yields is positive, |
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151 // and continues to yield until the value reverts to 0. |
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152 // (2) An asynchronous request, on the other hand, is used by iCMS |
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153 // for the stop_icms() operation. A single yield satisfies all of |
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154 // the outstanding asynch yield requests, of which there may |
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155 // occasionally be several in close succession. To accomplish |
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156 // this, an asynch-requesting thread atomically increments both |
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157 // _pending_yields and _pending_decrements. An asynchr requesting |
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158 // thread does not wait and "acknowledge" completion of an operation |
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159 // and deregister the request, like the synchronous version described |
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160 // above does. In turn, after yielding, the CMS thread decrements both |
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161 // _pending_yields and _pending_decrements by the value seen in |
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162 // _pending_decrements before the decrement. |
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163 // NOTE: The above scheme is isomorphic to having two request counters, |
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164 // one for async requests and one for sync requests, and for the CMS thread |
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165 // to check the sum of the two counters to decide whether it should yield |
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166 // and to clear only the async counter when it yields. However, it turns out |
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167 // to be more efficient for CMS code to just check a single counter |
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168 // _pending_yields that holds the sum (of both sync and async requests), and |
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169 // a second counter _pending_decrements that only holds the async requests, |
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170 // for greater efficiency, since in a typical CMS run, there are many more |
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171 // pontential (i.e. static) yield points than there are actual |
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172 // (i.e. dynamic) yields because of requests, which are few and far between. |
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173 // |
| 0 | 174 // Note that, while "_pending_yields >= _pending_decrements" is an invariant, |
| 175 // we cannot easily test that invariant, since the counters are manipulated via | |
| 176 // atomic instructions without explicit locking and we cannot read | |
| 177 // the two counters atomically together: one suggestion is to | |
| 178 // use (for example) 16-bit counters so as to be able to read the | |
| 179 // two counters atomically even on 32-bit platforms. Notice that | |
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180 // the second assert in acknowledge_yield_request() below does indeed |
| 0 | 181 // check a form of the above invariant, albeit indirectly. |
| 182 | |
| 183 static void increment_pending_yields() { | |
| 184 Atomic::inc(&_pending_yields); | |
| 185 assert(_pending_yields >= 0, "can't be negative"); | |
| 186 } | |
| 187 static void decrement_pending_yields() { | |
| 188 Atomic::dec(&_pending_yields); | |
| 189 assert(_pending_yields >= 0, "can't be negative"); | |
| 190 } | |
| 191 static void asynchronous_yield_request() { | |
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192 assert(CMSIncrementalMode, "Currently only used w/iCMS"); |
| 0 | 193 increment_pending_yields(); |
| 194 Atomic::inc(&_pending_decrements); | |
| 195 assert(_pending_decrements >= 0, "can't be negative"); | |
| 196 } | |
| 197 static void acknowledge_yield_request() { | |
| 198 jint decrement = _pending_decrements; | |
| 199 if (decrement > 0) { | |
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200 assert(CMSIncrementalMode, "Currently only used w/iCMS"); |
| 0 | 201 // Order important to preserve: _pending_yields >= _pending_decrements |
| 202 Atomic::add(-decrement, &_pending_decrements); | |
| 203 Atomic::add(-decrement, &_pending_yields); | |
| 204 assert(_pending_decrements >= 0, "can't be negative"); | |
| 205 assert(_pending_yields >= 0, "can't be negative"); | |
| 206 } | |
| 207 } | |
| 208 static bool should_yield() { return _pending_yields > 0; } | |
| 209 | |
| 210 // CMS incremental mode. | |
| 211 static void start_icms(); // notify thread to start a quantum of work | |
| 212 static void stop_icms(); // request thread to stop working | |
| 213 void icms_wait(); // if asked to stop, wait until notified to start | |
| 214 | |
| 215 // Incremental mode is enabled globally by the flag CMSIncrementalMode. It | |
| 216 // must also be enabled/disabled dynamically to allow foreground collections. | |
| 217 static inline void enable_icms() { _icms_enabled = true; } | |
| 218 static inline void disable_icms() { _icms_enabled = false; } | |
| 219 static inline void set_icms_enabled(bool val) { _icms_enabled = val; } | |
| 220 static inline bool icms_enabled() { return _icms_enabled; } | |
| 221 }; | |
| 222 | |
| 223 inline void ConcurrentMarkSweepThread::trace_state(const char* desc) { | |
| 224 if (CMSTraceThreadState) { | |
| 225 char buf[128]; | |
| 226 TimeStamp& ts = gclog_or_tty->time_stamp(); | |
| 227 if (!ts.is_updated()) { | |
| 228 ts.update(); | |
| 229 } | |
| 230 jio_snprintf(buf, sizeof(buf), " [%.3f: CMSThread %s] ", | |
| 231 ts.seconds(), desc); | |
| 232 buf[sizeof(buf) - 1] = '\0'; | |
| 233 gclog_or_tty->print(buf); | |
| 234 } | |
| 235 } | |
| 236 | |
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237 // For scoped increment/decrement of (synchronous) yield requests |
| 0 | 238 class CMSSynchronousYieldRequest: public StackObj { |
| 239 public: | |
| 240 CMSSynchronousYieldRequest() { | |
| 241 ConcurrentMarkSweepThread::increment_pending_yields(); | |
| 242 } | |
| 243 ~CMSSynchronousYieldRequest() { | |
| 244 ConcurrentMarkSweepThread::decrement_pending_yields(); | |
| 245 } | |
| 246 }; | |
| 247 | |
| 248 // Used to emit a warning in case of unexpectedly excessive | |
| 249 // looping (in "apparently endless loops") in CMS code. | |
| 250 class CMSLoopCountWarn: public StackObj { | |
| 251 private: | |
| 252 const char* _src; | |
| 253 const char* _msg; | |
| 254 const intx _threshold; | |
| 255 intx _ticks; | |
| 256 | |
| 257 public: | |
| 258 inline CMSLoopCountWarn(const char* src, const char* msg, | |
| 259 const intx threshold) : | |
| 260 _src(src), _msg(msg), _threshold(threshold), _ticks(0) { } | |
| 261 | |
| 262 inline void tick() { | |
| 263 _ticks++; | |
| 264 if (CMSLoopWarn && _ticks % _threshold == 0) { | |
| 265 warning("%s has looped %d times %s", _src, _ticks, _msg); | |
| 266 } | |
| 267 } | |
| 268 }; | |
| 1972 | 269 |
| 270 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPTHREAD_HPP |