239
240 void VM_GenCollectFullConcurrent::doit_epilogue() {
241 Thread* thr = Thread::current();
242 assert(thr->is_Java_thread(), "just checking");
243 JavaThread* jt = (JavaThread*)thr;
244 // Release the Heap_lock first.
245 Heap_lock->unlock();
246 release_and_notify_pending_list_lock();
247
248 // It is fine to test whether completed collections has
249 // exceeded our request count without locking because
250 // the completion count is monotonically increasing;
251 // this will break for very long-running apps when the
252 // count overflows and wraps around. XXX fix me !!!
253 // e.g. at the rate of 1 full gc per ms, this could
254 // overflow in about 1000 years.
255 GenCollectedHeap* gch = GenCollectedHeap::heap();
256 if (_gc_cause != GCCause::_gc_locker &&
257 gch->total_full_collections_completed() <= _full_gc_count_before) {
258 // maybe we should change the condition to test _gc_cause ==
259 // GCCause::_java_lang_system_gc, instead of
260 // _gc_cause != GCCause::_gc_locker
261 assert(_gc_cause == GCCause::_java_lang_system_gc,
262 "the only way to get here if this was a System.gc()-induced GC");
263 assert(ExplicitGCInvokesConcurrent, "Error");
264 // Now, wait for witnessing concurrent gc cycle to complete,
265 // but do so in native mode, because we want to lock the
266 // FullGCEvent_lock, which may be needed by the VM thread
267 // or by the CMS thread, so we do not want to be suspended
268 // while holding that lock.
269 ThreadToNativeFromVM native(jt);
270 MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
271 // Either a concurrent or a stop-world full gc is sufficient
272 // witness to our request.
273 while (gch->total_full_collections_completed() <= _full_gc_count_before) {
274 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
275 }
276 }
277 }
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239
240 void VM_GenCollectFullConcurrent::doit_epilogue() {
241 Thread* thr = Thread::current();
242 assert(thr->is_Java_thread(), "just checking");
243 JavaThread* jt = (JavaThread*)thr;
244 // Release the Heap_lock first.
245 Heap_lock->unlock();
246 release_and_notify_pending_list_lock();
247
248 // It is fine to test whether completed collections has
249 // exceeded our request count without locking because
250 // the completion count is monotonically increasing;
251 // this will break for very long-running apps when the
252 // count overflows and wraps around. XXX fix me !!!
253 // e.g. at the rate of 1 full gc per ms, this could
254 // overflow in about 1000 years.
255 GenCollectedHeap* gch = GenCollectedHeap::heap();
256 if (_gc_cause != GCCause::_gc_locker &&
257 gch->total_full_collections_completed() <= _full_gc_count_before) {
258 // maybe we should change the condition to test _gc_cause ==
259 // GCCause::_java_lang_system_gc or _dcmd_gc_run, instead of
260 // _gc_cause != GCCause::_gc_locker
261 assert(GCCause::is_user_requested_gc(_gc_cause),
262 "the only way to get here if this was a System.gc()-induced GC");
263 assert(ExplicitGCInvokesConcurrent, "Error");
264 // Now, wait for witnessing concurrent gc cycle to complete,
265 // but do so in native mode, because we want to lock the
266 // FullGCEvent_lock, which may be needed by the VM thread
267 // or by the CMS thread, so we do not want to be suspended
268 // while holding that lock.
269 ThreadToNativeFromVM native(jt);
270 MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
271 // Either a concurrent or a stop-world full gc is sufficient
272 // witness to our request.
273 while (gch->total_full_collections_completed() <= _full_gc_count_before) {
274 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
275 }
276 }
277 }
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