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annotate src/share/vm/memory/gcLocker.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 | c18cbe5936b8 |
| children | f08d439fab8c |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 1972 | 2 * Copyright (c) 1997, 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_MEMORY_GCLOCKER_HPP |
| 26 #define SHARE_VM_MEMORY_GCLOCKER_HPP | |
| 27 | |
| 28 #include "gc_interface/collectedHeap.hpp" | |
| 29 #include "memory/genCollectedHeap.hpp" | |
| 30 #include "memory/universe.hpp" | |
| 31 #include "oops/oop.hpp" | |
| 32 #ifdef TARGET_OS_FAMILY_linux | |
| 33 # include "os_linux.inline.hpp" | |
| 34 # include "thread_linux.inline.hpp" | |
| 35 #endif | |
| 36 #ifdef TARGET_OS_FAMILY_solaris | |
| 37 # include "os_solaris.inline.hpp" | |
| 38 # include "thread_solaris.inline.hpp" | |
| 39 #endif | |
| 40 #ifdef TARGET_OS_FAMILY_windows | |
| 41 # include "os_windows.inline.hpp" | |
| 42 # include "thread_windows.inline.hpp" | |
| 43 #endif | |
| 44 | |
| 0 | 45 // The direct lock/unlock calls do not force a collection if an unlock |
| 46 // decrements the count to zero. Avoid calling these if at all possible. | |
| 47 | |
| 48 class GC_locker: public AllStatic { | |
| 49 private: | |
| 50 static volatile jint _jni_lock_count; // number of jni active instances | |
| 51 static volatile jint _lock_count; // number of other active instances | |
| 52 static volatile bool _needs_gc; // heap is filling, we need a GC | |
| 53 // note: bool is typedef'd as jint | |
| 54 static volatile bool _doing_gc; // unlock_critical() is doing a GC | |
| 55 | |
| 56 // Accessors | |
| 57 static bool is_jni_active() { | |
| 58 return _jni_lock_count > 0; | |
| 59 } | |
| 60 | |
| 61 static void set_needs_gc() { | |
| 62 assert(SafepointSynchronize::is_at_safepoint(), | |
| 63 "needs_gc is only set at a safepoint"); | |
| 64 _needs_gc = true; | |
| 65 } | |
| 66 | |
| 67 static void clear_needs_gc() { | |
| 68 assert_lock_strong(JNICritical_lock); | |
| 69 _needs_gc = false; | |
| 70 } | |
| 71 | |
| 72 static void jni_lock() { | |
| 73 Atomic::inc(&_jni_lock_count); | |
| 74 CHECK_UNHANDLED_OOPS_ONLY( | |
| 75 if (CheckUnhandledOops) { Thread::current()->_gc_locked_out_count++; }) | |
| 76 assert(Universe::heap() == NULL || !Universe::heap()->is_gc_active(), | |
| 77 "locking failed"); | |
| 78 } | |
| 79 | |
| 80 static void jni_unlock() { | |
| 81 Atomic::dec(&_jni_lock_count); | |
| 82 CHECK_UNHANDLED_OOPS_ONLY( | |
| 83 if (CheckUnhandledOops) { Thread::current()->_gc_locked_out_count--; }) | |
| 84 } | |
| 85 | |
| 86 static void jni_lock_slow(); | |
| 87 static void jni_unlock_slow(); | |
| 88 | |
| 89 public: | |
| 90 // Accessors | |
| 91 static bool is_active(); | |
| 92 static bool needs_gc() { return _needs_gc; } | |
| 93 // Shorthand | |
| 94 static bool is_active_and_needs_gc() { return is_active() && needs_gc();} | |
| 95 | |
| 96 // Calls set_needs_gc() if is_active() is true. Returns is_active(). | |
| 97 static bool check_active_before_gc(); | |
| 98 | |
| 99 // Stalls the caller (who should not be in a jni critical section) | |
| 100 // until needs_gc() clears. Note however that needs_gc() may be | |
| 101 // set at a subsequent safepoint and/or cleared under the | |
| 102 // JNICritical_lock, so the caller may not safely assert upon | |
| 103 // return from this method that "!needs_gc()" since that is | |
| 104 // not a stable predicate. | |
| 105 static void stall_until_clear(); | |
| 106 | |
| 107 // Non-structured GC locking: currently needed for JNI. Use with care! | |
| 108 static void lock(); | |
| 109 static void unlock(); | |
| 110 | |
| 111 // The following two methods are used for JNI critical regions. | |
| 112 // If we find that we failed to perform a GC because the GC_locker | |
| 113 // was active, arrange for one as soon as possible by allowing | |
| 114 // all threads in critical regions to complete, but not allowing | |
| 115 // other critical regions to be entered. The reasons for that are: | |
| 116 // 1) a GC request won't be starved by overlapping JNI critical | |
| 117 // region activities, which can cause unnecessary OutOfMemory errors. | |
| 118 // 2) even if allocation requests can still be satisfied before GC locker | |
| 119 // becomes inactive, for example, in tenured generation possibly with | |
| 120 // heap expansion, those allocations can trigger lots of safepointing | |
| 121 // attempts (ineffective GC attempts) and require Heap_lock which | |
| 122 // slow down allocations tremendously. | |
| 123 // | |
| 124 // Note that critical regions can be nested in a single thread, so | |
| 125 // we must allow threads already in critical regions to continue. | |
| 126 // | |
| 127 // JNI critical regions are the only participants in this scheme | |
| 128 // because they are, by spec, well bounded while in a critical region. | |
| 129 // | |
| 130 // Each of the following two method is split into a fast path and a slow | |
| 131 // path. JNICritical_lock is only grabbed in the slow path. | |
| 132 // _needs_gc is initially false and every java thread will go | |
| 133 // through the fast path (which does the same thing as the slow path | |
| 134 // when _needs_gc is false). When GC happens at a safepoint, | |
| 135 // GC_locker::is_active() is checked. Since there is no safepoint in the | |
| 136 // fast path of lock_critical() and unlock_critical(), there is no race | |
| 137 // condition between the fast path and GC. After _needs_gc is set at a | |
| 138 // safepoint, every thread will go through the slow path after the safepoint. | |
| 139 // Since after a safepoint, each of the following two methods is either | |
| 140 // entered from the method entry and falls into the slow path, or is | |
| 141 // resumed from the safepoints in the method, which only exist in the slow | |
| 142 // path. So when _needs_gc is set, the slow path is always taken, till | |
| 143 // _needs_gc is cleared. | |
| 144 static void lock_critical(JavaThread* thread); | |
| 145 static void unlock_critical(JavaThread* thread); | |
| 146 }; | |
| 147 | |
| 148 | |
| 149 // A No_GC_Verifier object can be placed in methods where one assumes that | |
| 150 // no garbage collection will occur. The destructor will verify this property | |
| 151 // unless the constructor is called with argument false (not verifygc). | |
| 152 // | |
| 153 // The check will only be done in debug mode and if verifygc true. | |
| 154 | |
| 155 class No_GC_Verifier: public StackObj { | |
| 156 friend class Pause_No_GC_Verifier; | |
| 157 | |
| 158 protected: | |
| 159 bool _verifygc; | |
| 160 unsigned int _old_invocations; | |
| 161 | |
| 162 public: | |
| 163 #ifdef ASSERT | |
| 164 No_GC_Verifier(bool verifygc = true); | |
| 165 ~No_GC_Verifier(); | |
| 166 #else | |
| 167 No_GC_Verifier(bool verifygc = true) {} | |
| 168 ~No_GC_Verifier() {} | |
| 169 #endif | |
| 170 }; | |
| 171 | |
| 172 // A Pause_No_GC_Verifier is used to temporarily pause the behavior | |
| 173 // of a No_GC_Verifier object. If we are not in debug mode or if the | |
| 174 // No_GC_Verifier object has a _verifygc value of false, then there | |
| 175 // is nothing to do. | |
| 176 | |
| 177 class Pause_No_GC_Verifier: public StackObj { | |
| 178 private: | |
| 179 No_GC_Verifier * _ngcv; | |
| 180 | |
| 181 public: | |
| 182 #ifdef ASSERT | |
| 183 Pause_No_GC_Verifier(No_GC_Verifier * ngcv); | |
| 184 ~Pause_No_GC_Verifier(); | |
| 185 #else | |
| 186 Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {} | |
| 187 ~Pause_No_GC_Verifier() {} | |
| 188 #endif | |
| 189 }; | |
| 190 | |
| 191 | |
| 192 // A No_Safepoint_Verifier object will throw an assertion failure if | |
| 193 // the current thread passes a possible safepoint while this object is | |
| 194 // instantiated. A safepoint, will either be: an oop allocation, blocking | |
| 195 // on a Mutex or JavaLock, or executing a VM operation. | |
| 196 // | |
| 197 // If StrictSafepointChecks is turned off, it degrades into a No_GC_Verifier | |
| 198 // | |
| 199 class No_Safepoint_Verifier : public No_GC_Verifier { | |
| 200 friend class Pause_No_Safepoint_Verifier; | |
| 201 | |
| 202 private: | |
| 203 bool _activated; | |
| 204 Thread *_thread; | |
| 205 public: | |
| 206 #ifdef ASSERT | |
|
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207 No_Safepoint_Verifier(bool activated = true, bool verifygc = true ) : |
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208 No_GC_Verifier(verifygc), |
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209 _activated(activated) { |
| 0 | 210 _thread = Thread::current(); |
| 211 if (_activated) { | |
| 212 _thread->_allow_allocation_count++; | |
| 213 _thread->_allow_safepoint_count++; | |
| 214 } | |
| 215 } | |
| 216 | |
| 217 ~No_Safepoint_Verifier() { | |
| 218 if (_activated) { | |
| 219 _thread->_allow_allocation_count--; | |
| 220 _thread->_allow_safepoint_count--; | |
| 221 } | |
| 222 } | |
| 223 #else | |
| 224 No_Safepoint_Verifier(bool activated = true, bool verifygc = true) : No_GC_Verifier(verifygc){} | |
| 225 ~No_Safepoint_Verifier() {} | |
| 226 #endif | |
| 227 }; | |
| 228 | |
| 229 // A Pause_No_Safepoint_Verifier is used to temporarily pause the | |
| 230 // behavior of a No_Safepoint_Verifier object. If we are not in debug | |
| 231 // mode then there is nothing to do. If the No_Safepoint_Verifier | |
| 232 // object has an _activated value of false, then there is nothing to | |
| 233 // do for safepoint and allocation checking, but there may still be | |
| 234 // something to do for the underlying No_GC_Verifier object. | |
| 235 | |
| 236 class Pause_No_Safepoint_Verifier : public Pause_No_GC_Verifier { | |
| 237 private: | |
| 238 No_Safepoint_Verifier * _nsv; | |
| 239 | |
| 240 public: | |
| 241 #ifdef ASSERT | |
| 242 Pause_No_Safepoint_Verifier(No_Safepoint_Verifier * nsv) | |
| 243 : Pause_No_GC_Verifier(nsv) { | |
| 244 | |
| 245 _nsv = nsv; | |
| 246 if (_nsv->_activated) { | |
| 247 _nsv->_thread->_allow_allocation_count--; | |
| 248 _nsv->_thread->_allow_safepoint_count--; | |
| 249 } | |
| 250 } | |
| 251 | |
| 252 ~Pause_No_Safepoint_Verifier() { | |
| 253 if (_nsv->_activated) { | |
| 254 _nsv->_thread->_allow_allocation_count++; | |
| 255 _nsv->_thread->_allow_safepoint_count++; | |
| 256 } | |
| 257 } | |
| 258 #else | |
| 259 Pause_No_Safepoint_Verifier(No_Safepoint_Verifier * nsv) | |
| 260 : Pause_No_GC_Verifier(nsv) {} | |
| 261 ~Pause_No_Safepoint_Verifier() {} | |
| 262 #endif | |
| 263 }; | |
| 264 | |
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265 // A SkipGCALot object is used to elide the usual effect of gc-a-lot |
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266 // over a section of execution by a thread. Currently, it's used only to |
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267 // prevent re-entrant calls to GC. |
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268 class SkipGCALot : public StackObj { |
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269 private: |
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270 bool _saved; |
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271 Thread* _t; |
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272 |
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273 public: |
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274 #ifdef ASSERT |
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275 SkipGCALot(Thread* t) : _t(t) { |
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276 _saved = _t->skip_gcalot(); |
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277 _t->set_skip_gcalot(true); |
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278 } |
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279 |
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280 ~SkipGCALot() { |
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281 assert(_t->skip_gcalot(), "Save-restore protocol invariant"); |
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282 _t->set_skip_gcalot(_saved); |
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283 } |
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284 #else |
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285 SkipGCALot(Thread* t) { } |
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286 ~SkipGCALot() { } |
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287 #endif |
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288 }; |
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289 |
| 0 | 290 // JRT_LEAF currently can be called from either _thread_in_Java or |
| 291 // _thread_in_native mode. In _thread_in_native, it is ok | |
| 292 // for another thread to trigger GC. The rest of the JRT_LEAF | |
| 293 // rules apply. | |
| 294 class JRT_Leaf_Verifier : public No_Safepoint_Verifier { | |
| 295 static bool should_verify_GC(); | |
| 296 public: | |
| 297 #ifdef ASSERT | |
| 298 JRT_Leaf_Verifier(); | |
| 299 ~JRT_Leaf_Verifier(); | |
| 300 #else | |
| 301 JRT_Leaf_Verifier() {} | |
| 302 ~JRT_Leaf_Verifier() {} | |
| 303 #endif | |
| 304 }; | |
| 305 | |
| 306 // A No_Alloc_Verifier object can be placed in methods where one assumes that | |
| 307 // no allocation will occur. The destructor will verify this property | |
| 308 // unless the constructor is called with argument false (not activated). | |
| 309 // | |
| 310 // The check will only be done in debug mode and if activated. | |
| 311 // Note: this only makes sense at safepoints (otherwise, other threads may | |
| 312 // allocate concurrently.) | |
| 313 | |
| 314 class No_Alloc_Verifier : public StackObj { | |
| 315 private: | |
| 316 bool _activated; | |
| 317 | |
| 318 public: | |
| 319 #ifdef ASSERT | |
| 320 No_Alloc_Verifier(bool activated = true) { | |
| 321 _activated = activated; | |
| 322 if (_activated) Thread::current()->_allow_allocation_count++; | |
| 323 } | |
| 324 | |
| 325 ~No_Alloc_Verifier() { | |
| 326 if (_activated) Thread::current()->_allow_allocation_count--; | |
| 327 } | |
| 328 #else | |
| 329 No_Alloc_Verifier(bool activated = true) {} | |
| 330 ~No_Alloc_Verifier() {} | |
| 331 #endif | |
| 332 }; | |
| 1972 | 333 |
| 334 #endif // SHARE_VM_MEMORY_GCLOCKER_HPP |