Wed, 15 Feb 2012 10:12:55 -0800
7145537: minor tweaks to LogEvents
Reviewed-by: kvn, twisti
duke@435 | 1 | /* |
never@3494 | 2 | * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
trims@1907 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
trims@1907 | 20 | * or visit www.oracle.com if you need additional information or have any |
trims@1907 | 21 | * questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
stefank@2314 | 25 | #ifndef SHARE_VM_MEMORY_GCLOCKER_HPP |
stefank@2314 | 26 | #define SHARE_VM_MEMORY_GCLOCKER_HPP |
stefank@2314 | 27 | |
stefank@2314 | 28 | #include "gc_interface/collectedHeap.hpp" |
stefank@2314 | 29 | #include "memory/genCollectedHeap.hpp" |
stefank@2314 | 30 | #include "memory/universe.hpp" |
stefank@2314 | 31 | #include "oops/oop.hpp" |
stefank@2314 | 32 | #ifdef TARGET_OS_FAMILY_linux |
stefank@2314 | 33 | # include "os_linux.inline.hpp" |
stefank@2314 | 34 | # include "thread_linux.inline.hpp" |
stefank@2314 | 35 | #endif |
stefank@2314 | 36 | #ifdef TARGET_OS_FAMILY_solaris |
stefank@2314 | 37 | # include "os_solaris.inline.hpp" |
stefank@2314 | 38 | # include "thread_solaris.inline.hpp" |
stefank@2314 | 39 | #endif |
stefank@2314 | 40 | #ifdef TARGET_OS_FAMILY_windows |
stefank@2314 | 41 | # include "os_windows.inline.hpp" |
stefank@2314 | 42 | # include "thread_windows.inline.hpp" |
stefank@2314 | 43 | #endif |
never@3156 | 44 | #ifdef TARGET_OS_FAMILY_bsd |
never@3156 | 45 | # include "os_bsd.inline.hpp" |
never@3156 | 46 | # include "thread_bsd.inline.hpp" |
never@3156 | 47 | #endif |
stefank@2314 | 48 | |
duke@435 | 49 | // The direct lock/unlock calls do not force a collection if an unlock |
duke@435 | 50 | // decrements the count to zero. Avoid calling these if at all possible. |
duke@435 | 51 | |
duke@435 | 52 | class GC_locker: public AllStatic { |
duke@435 | 53 | private: |
never@3494 | 54 | // The _jni_lock_count keeps track of the number of threads that are |
never@3494 | 55 | // currently in a critical region. It's only kept up to date when |
never@3494 | 56 | // _needs_gc is true. The current value is computed during |
never@3494 | 57 | // safepointing and decremented during the slow path of GC_locker |
never@3494 | 58 | // unlocking. |
never@3494 | 59 | static volatile jint _jni_lock_count; // number of jni active instances. |
never@3494 | 60 | |
duke@435 | 61 | static volatile jint _lock_count; // number of other active instances |
duke@435 | 62 | static volatile bool _needs_gc; // heap is filling, we need a GC |
duke@435 | 63 | // note: bool is typedef'd as jint |
duke@435 | 64 | static volatile bool _doing_gc; // unlock_critical() is doing a GC |
duke@435 | 65 | |
never@3494 | 66 | #ifdef ASSERT |
never@3494 | 67 | // This lock count is updated for all operations and is used to |
never@3494 | 68 | // validate the jni_lock_count that is computed during safepoints. |
never@3494 | 69 | static volatile jint _debug_jni_lock_count; |
never@3494 | 70 | #endif |
never@3494 | 71 | |
duke@435 | 72 | // Accessors |
duke@435 | 73 | static bool is_jni_active() { |
never@3494 | 74 | assert(_needs_gc, "only valid when _needs_gc is set"); |
duke@435 | 75 | return _jni_lock_count > 0; |
duke@435 | 76 | } |
duke@435 | 77 | |
never@3494 | 78 | // At a safepoint, visit all threads and count the number of active |
never@3494 | 79 | // critical sections. This is used to ensure that all active |
never@3494 | 80 | // critical sections are exited before a new one is started. |
never@3494 | 81 | static void verify_critical_count() NOT_DEBUG_RETURN; |
duke@435 | 82 | |
never@3494 | 83 | static void jni_lock(JavaThread* thread); |
never@3494 | 84 | static void jni_unlock(JavaThread* thread); |
duke@435 | 85 | |
duke@435 | 86 | public: |
duke@435 | 87 | // Accessors |
duke@435 | 88 | static bool is_active(); |
duke@435 | 89 | static bool needs_gc() { return _needs_gc; } |
never@3494 | 90 | |
duke@435 | 91 | // Shorthand |
never@3494 | 92 | static bool is_active_and_needs_gc() { return needs_gc() && is_active(); } |
duke@435 | 93 | |
never@3494 | 94 | // In debug mode track the locking state at all times |
never@3494 | 95 | static void increment_debug_jni_lock_count() { |
never@3494 | 96 | #ifdef ASSERT |
never@3494 | 97 | assert(_debug_jni_lock_count >= 0, "bad value"); |
never@3494 | 98 | Atomic::inc(&_debug_jni_lock_count); |
never@3494 | 99 | #endif |
never@3494 | 100 | } |
never@3494 | 101 | static void decrement_debug_jni_lock_count() { |
never@3494 | 102 | #ifdef ASSERT |
never@3494 | 103 | assert(_debug_jni_lock_count > 0, "bad value"); |
never@3494 | 104 | Atomic::dec(&_debug_jni_lock_count); |
never@3494 | 105 | #endif |
never@3494 | 106 | } |
never@3494 | 107 | |
never@3494 | 108 | // Set the current lock count |
never@3494 | 109 | static void set_jni_lock_count(int count) { |
never@3494 | 110 | _jni_lock_count = count; |
never@3494 | 111 | verify_critical_count(); |
never@3494 | 112 | } |
never@3494 | 113 | |
never@3494 | 114 | // Sets _needs_gc if is_active() is true. Returns is_active(). |
duke@435 | 115 | static bool check_active_before_gc(); |
duke@435 | 116 | |
duke@435 | 117 | // Stalls the caller (who should not be in a jni critical section) |
duke@435 | 118 | // until needs_gc() clears. Note however that needs_gc() may be |
duke@435 | 119 | // set at a subsequent safepoint and/or cleared under the |
duke@435 | 120 | // JNICritical_lock, so the caller may not safely assert upon |
duke@435 | 121 | // return from this method that "!needs_gc()" since that is |
duke@435 | 122 | // not a stable predicate. |
duke@435 | 123 | static void stall_until_clear(); |
duke@435 | 124 | |
duke@435 | 125 | // Non-structured GC locking: currently needed for JNI. Use with care! |
duke@435 | 126 | static void lock(); |
duke@435 | 127 | static void unlock(); |
duke@435 | 128 | |
duke@435 | 129 | // The following two methods are used for JNI critical regions. |
duke@435 | 130 | // If we find that we failed to perform a GC because the GC_locker |
duke@435 | 131 | // was active, arrange for one as soon as possible by allowing |
duke@435 | 132 | // all threads in critical regions to complete, but not allowing |
duke@435 | 133 | // other critical regions to be entered. The reasons for that are: |
duke@435 | 134 | // 1) a GC request won't be starved by overlapping JNI critical |
duke@435 | 135 | // region activities, which can cause unnecessary OutOfMemory errors. |
duke@435 | 136 | // 2) even if allocation requests can still be satisfied before GC locker |
duke@435 | 137 | // becomes inactive, for example, in tenured generation possibly with |
duke@435 | 138 | // heap expansion, those allocations can trigger lots of safepointing |
duke@435 | 139 | // attempts (ineffective GC attempts) and require Heap_lock which |
duke@435 | 140 | // slow down allocations tremendously. |
duke@435 | 141 | // |
duke@435 | 142 | // Note that critical regions can be nested in a single thread, so |
duke@435 | 143 | // we must allow threads already in critical regions to continue. |
duke@435 | 144 | // |
duke@435 | 145 | // JNI critical regions are the only participants in this scheme |
duke@435 | 146 | // because they are, by spec, well bounded while in a critical region. |
duke@435 | 147 | // |
never@3494 | 148 | // Each of the following two method is split into a fast path and a |
never@3494 | 149 | // slow path. JNICritical_lock is only grabbed in the slow path. |
duke@435 | 150 | // _needs_gc is initially false and every java thread will go |
never@3494 | 151 | // through the fast path, which simply increments or decrements the |
never@3494 | 152 | // current thread's critical count. When GC happens at a safepoint, |
never@3494 | 153 | // GC_locker::is_active() is checked. Since there is no safepoint in |
never@3494 | 154 | // the fast path of lock_critical() and unlock_critical(), there is |
never@3494 | 155 | // no race condition between the fast path and GC. After _needs_gc |
never@3494 | 156 | // is set at a safepoint, every thread will go through the slow path |
never@3494 | 157 | // after the safepoint. Since after a safepoint, each of the |
never@3494 | 158 | // following two methods is either entered from the method entry and |
never@3494 | 159 | // falls into the slow path, or is resumed from the safepoints in |
never@3494 | 160 | // the method, which only exist in the slow path. So when _needs_gc |
never@3494 | 161 | // is set, the slow path is always taken, till _needs_gc is cleared. |
duke@435 | 162 | static void lock_critical(JavaThread* thread); |
duke@435 | 163 | static void unlock_critical(JavaThread* thread); |
never@3500 | 164 | |
never@3500 | 165 | static address needs_gc_address() { return (address) &_needs_gc; } |
duke@435 | 166 | }; |
duke@435 | 167 | |
duke@435 | 168 | |
duke@435 | 169 | // A No_GC_Verifier object can be placed in methods where one assumes that |
duke@435 | 170 | // no garbage collection will occur. The destructor will verify this property |
duke@435 | 171 | // unless the constructor is called with argument false (not verifygc). |
duke@435 | 172 | // |
duke@435 | 173 | // The check will only be done in debug mode and if verifygc true. |
duke@435 | 174 | |
duke@435 | 175 | class No_GC_Verifier: public StackObj { |
duke@435 | 176 | friend class Pause_No_GC_Verifier; |
duke@435 | 177 | |
duke@435 | 178 | protected: |
duke@435 | 179 | bool _verifygc; |
duke@435 | 180 | unsigned int _old_invocations; |
duke@435 | 181 | |
duke@435 | 182 | public: |
duke@435 | 183 | #ifdef ASSERT |
duke@435 | 184 | No_GC_Verifier(bool verifygc = true); |
duke@435 | 185 | ~No_GC_Verifier(); |
duke@435 | 186 | #else |
duke@435 | 187 | No_GC_Verifier(bool verifygc = true) {} |
duke@435 | 188 | ~No_GC_Verifier() {} |
duke@435 | 189 | #endif |
duke@435 | 190 | }; |
duke@435 | 191 | |
duke@435 | 192 | // A Pause_No_GC_Verifier is used to temporarily pause the behavior |
duke@435 | 193 | // of a No_GC_Verifier object. If we are not in debug mode or if the |
duke@435 | 194 | // No_GC_Verifier object has a _verifygc value of false, then there |
duke@435 | 195 | // is nothing to do. |
duke@435 | 196 | |
duke@435 | 197 | class Pause_No_GC_Verifier: public StackObj { |
duke@435 | 198 | private: |
duke@435 | 199 | No_GC_Verifier * _ngcv; |
duke@435 | 200 | |
duke@435 | 201 | public: |
duke@435 | 202 | #ifdef ASSERT |
duke@435 | 203 | Pause_No_GC_Verifier(No_GC_Verifier * ngcv); |
duke@435 | 204 | ~Pause_No_GC_Verifier(); |
duke@435 | 205 | #else |
duke@435 | 206 | Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {} |
duke@435 | 207 | ~Pause_No_GC_Verifier() {} |
duke@435 | 208 | #endif |
duke@435 | 209 | }; |
duke@435 | 210 | |
duke@435 | 211 | |
duke@435 | 212 | // A No_Safepoint_Verifier object will throw an assertion failure if |
duke@435 | 213 | // the current thread passes a possible safepoint while this object is |
duke@435 | 214 | // instantiated. A safepoint, will either be: an oop allocation, blocking |
duke@435 | 215 | // on a Mutex or JavaLock, or executing a VM operation. |
duke@435 | 216 | // |
duke@435 | 217 | // If StrictSafepointChecks is turned off, it degrades into a No_GC_Verifier |
duke@435 | 218 | // |
duke@435 | 219 | class No_Safepoint_Verifier : public No_GC_Verifier { |
duke@435 | 220 | friend class Pause_No_Safepoint_Verifier; |
duke@435 | 221 | |
duke@435 | 222 | private: |
duke@435 | 223 | bool _activated; |
duke@435 | 224 | Thread *_thread; |
duke@435 | 225 | public: |
duke@435 | 226 | #ifdef ASSERT |
never@533 | 227 | No_Safepoint_Verifier(bool activated = true, bool verifygc = true ) : |
never@533 | 228 | No_GC_Verifier(verifygc), |
never@533 | 229 | _activated(activated) { |
duke@435 | 230 | _thread = Thread::current(); |
duke@435 | 231 | if (_activated) { |
duke@435 | 232 | _thread->_allow_allocation_count++; |
duke@435 | 233 | _thread->_allow_safepoint_count++; |
duke@435 | 234 | } |
duke@435 | 235 | } |
duke@435 | 236 | |
duke@435 | 237 | ~No_Safepoint_Verifier() { |
duke@435 | 238 | if (_activated) { |
duke@435 | 239 | _thread->_allow_allocation_count--; |
duke@435 | 240 | _thread->_allow_safepoint_count--; |
duke@435 | 241 | } |
duke@435 | 242 | } |
duke@435 | 243 | #else |
duke@435 | 244 | No_Safepoint_Verifier(bool activated = true, bool verifygc = true) : No_GC_Verifier(verifygc){} |
duke@435 | 245 | ~No_Safepoint_Verifier() {} |
duke@435 | 246 | #endif |
duke@435 | 247 | }; |
duke@435 | 248 | |
duke@435 | 249 | // A Pause_No_Safepoint_Verifier is used to temporarily pause the |
duke@435 | 250 | // behavior of a No_Safepoint_Verifier object. If we are not in debug |
duke@435 | 251 | // mode then there is nothing to do. If the No_Safepoint_Verifier |
duke@435 | 252 | // object has an _activated value of false, then there is nothing to |
duke@435 | 253 | // do for safepoint and allocation checking, but there may still be |
duke@435 | 254 | // something to do for the underlying No_GC_Verifier object. |
duke@435 | 255 | |
duke@435 | 256 | class Pause_No_Safepoint_Verifier : public Pause_No_GC_Verifier { |
duke@435 | 257 | private: |
duke@435 | 258 | No_Safepoint_Verifier * _nsv; |
duke@435 | 259 | |
duke@435 | 260 | public: |
duke@435 | 261 | #ifdef ASSERT |
duke@435 | 262 | Pause_No_Safepoint_Verifier(No_Safepoint_Verifier * nsv) |
duke@435 | 263 | : Pause_No_GC_Verifier(nsv) { |
duke@435 | 264 | |
duke@435 | 265 | _nsv = nsv; |
duke@435 | 266 | if (_nsv->_activated) { |
duke@435 | 267 | _nsv->_thread->_allow_allocation_count--; |
duke@435 | 268 | _nsv->_thread->_allow_safepoint_count--; |
duke@435 | 269 | } |
duke@435 | 270 | } |
duke@435 | 271 | |
duke@435 | 272 | ~Pause_No_Safepoint_Verifier() { |
duke@435 | 273 | if (_nsv->_activated) { |
duke@435 | 274 | _nsv->_thread->_allow_allocation_count++; |
duke@435 | 275 | _nsv->_thread->_allow_safepoint_count++; |
duke@435 | 276 | } |
duke@435 | 277 | } |
duke@435 | 278 | #else |
duke@435 | 279 | Pause_No_Safepoint_Verifier(No_Safepoint_Verifier * nsv) |
duke@435 | 280 | : Pause_No_GC_Verifier(nsv) {} |
duke@435 | 281 | ~Pause_No_Safepoint_Verifier() {} |
duke@435 | 282 | #endif |
duke@435 | 283 | }; |
duke@435 | 284 | |
ysr@1241 | 285 | // A SkipGCALot object is used to elide the usual effect of gc-a-lot |
ysr@1241 | 286 | // over a section of execution by a thread. Currently, it's used only to |
ysr@1241 | 287 | // prevent re-entrant calls to GC. |
ysr@1241 | 288 | class SkipGCALot : public StackObj { |
ysr@1241 | 289 | private: |
ysr@1241 | 290 | bool _saved; |
ysr@1241 | 291 | Thread* _t; |
ysr@1241 | 292 | |
ysr@1241 | 293 | public: |
ysr@1241 | 294 | #ifdef ASSERT |
ysr@1241 | 295 | SkipGCALot(Thread* t) : _t(t) { |
ysr@1241 | 296 | _saved = _t->skip_gcalot(); |
ysr@1241 | 297 | _t->set_skip_gcalot(true); |
ysr@1241 | 298 | } |
ysr@1241 | 299 | |
ysr@1241 | 300 | ~SkipGCALot() { |
ysr@1241 | 301 | assert(_t->skip_gcalot(), "Save-restore protocol invariant"); |
ysr@1241 | 302 | _t->set_skip_gcalot(_saved); |
ysr@1241 | 303 | } |
ysr@1241 | 304 | #else |
ysr@1241 | 305 | SkipGCALot(Thread* t) { } |
ysr@1241 | 306 | ~SkipGCALot() { } |
ysr@1241 | 307 | #endif |
ysr@1241 | 308 | }; |
ysr@1241 | 309 | |
duke@435 | 310 | // JRT_LEAF currently can be called from either _thread_in_Java or |
duke@435 | 311 | // _thread_in_native mode. In _thread_in_native, it is ok |
duke@435 | 312 | // for another thread to trigger GC. The rest of the JRT_LEAF |
duke@435 | 313 | // rules apply. |
duke@435 | 314 | class JRT_Leaf_Verifier : public No_Safepoint_Verifier { |
duke@435 | 315 | static bool should_verify_GC(); |
duke@435 | 316 | public: |
duke@435 | 317 | #ifdef ASSERT |
duke@435 | 318 | JRT_Leaf_Verifier(); |
duke@435 | 319 | ~JRT_Leaf_Verifier(); |
duke@435 | 320 | #else |
duke@435 | 321 | JRT_Leaf_Verifier() {} |
duke@435 | 322 | ~JRT_Leaf_Verifier() {} |
duke@435 | 323 | #endif |
duke@435 | 324 | }; |
duke@435 | 325 | |
duke@435 | 326 | // A No_Alloc_Verifier object can be placed in methods where one assumes that |
duke@435 | 327 | // no allocation will occur. The destructor will verify this property |
duke@435 | 328 | // unless the constructor is called with argument false (not activated). |
duke@435 | 329 | // |
duke@435 | 330 | // The check will only be done in debug mode and if activated. |
duke@435 | 331 | // Note: this only makes sense at safepoints (otherwise, other threads may |
duke@435 | 332 | // allocate concurrently.) |
duke@435 | 333 | |
duke@435 | 334 | class No_Alloc_Verifier : public StackObj { |
duke@435 | 335 | private: |
duke@435 | 336 | bool _activated; |
duke@435 | 337 | |
duke@435 | 338 | public: |
duke@435 | 339 | #ifdef ASSERT |
duke@435 | 340 | No_Alloc_Verifier(bool activated = true) { |
duke@435 | 341 | _activated = activated; |
duke@435 | 342 | if (_activated) Thread::current()->_allow_allocation_count++; |
duke@435 | 343 | } |
duke@435 | 344 | |
duke@435 | 345 | ~No_Alloc_Verifier() { |
duke@435 | 346 | if (_activated) Thread::current()->_allow_allocation_count--; |
duke@435 | 347 | } |
duke@435 | 348 | #else |
duke@435 | 349 | No_Alloc_Verifier(bool activated = true) {} |
duke@435 | 350 | ~No_Alloc_Verifier() {} |
duke@435 | 351 | #endif |
duke@435 | 352 | }; |
stefank@2314 | 353 | |
stefank@2314 | 354 | #endif // SHARE_VM_MEMORY_GCLOCKER_HPP |