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comparison src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp @ 1520:bb843ebc7c55

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6919638: CMS: ExplicitGCInvokesConcurrent misinteracts with gc locker Summary: GC-locker induced concurrent full gc should be asynchronous; policy now controlled by a separate flag, which defaults to false. Reviewed-by: jmasa
author ysr
date Mon, 03 May 2010 20:19:05 -0700
parents a61af66fc99e
children c18cbe5936b8
comparison
equal deleted inserted replaced
1519:7145628c2fa2 1520:bb843ebc7c55
161 161
162 // VM operation to invoke a concurrent collection of a 162 // VM operation to invoke a concurrent collection of a
163 // GenCollectedHeap heap. 163 // GenCollectedHeap heap.
164 void VM_GenCollectFullConcurrent::doit() { 164 void VM_GenCollectFullConcurrent::doit() {
165 assert(Thread::current()->is_VM_thread(), "Should be VM thread"); 165 assert(Thread::current()->is_VM_thread(), "Should be VM thread");
166 assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected");
166 167
167 GenCollectedHeap* gch = GenCollectedHeap::heap(); 168 GenCollectedHeap* gch = GenCollectedHeap::heap();
168 if (_gc_count_before == gch->total_collections()) { 169 if (_gc_count_before == gch->total_collections()) {
169 // The "full" of do_full_collection call below "forces" 170 // The "full" of do_full_collection call below "forces"
170 // a collection; the second arg, 0, below ensures that 171 // a collection; the second arg, 0, below ensures that
188 if (gch->total_full_collections() == _full_gc_count_before) { 189 if (gch->total_full_collections() == _full_gc_count_before) {
189 // Disable iCMS until the full collection is done. 190 // Disable iCMS until the full collection is done.
190 CMSCollector::disable_icms(); 191 CMSCollector::disable_icms();
191 // In case CMS thread was in icms_wait(), wake it up. 192 // In case CMS thread was in icms_wait(), wake it up.
192 CMSCollector::start_icms(); 193 CMSCollector::start_icms();
193 // Nudge the CMS thread to start a concurrent collection 194 // Nudge the CMS thread to start a concurrent collection.
194 CMSCollector::request_full_gc(_full_gc_count_before); 195 CMSCollector::request_full_gc(_full_gc_count_before);
195 } else { 196 } else {
196 FullGCCount_lock->notify_all(); // Inform the Java thread its work is done 197 FullGCCount_lock->notify_all(); // Inform the Java thread its work is done
197 } 198 }
198 } 199 }
229 // this will break for very long-running apps when the 230 // this will break for very long-running apps when the
230 // count overflows and wraps around. XXX fix me !!! 231 // count overflows and wraps around. XXX fix me !!!
231 // e.g. at the rate of 1 full gc per ms, this could 232 // e.g. at the rate of 1 full gc per ms, this could
232 // overflow in about 1000 years. 233 // overflow in about 1000 years.
233 GenCollectedHeap* gch = GenCollectedHeap::heap(); 234 GenCollectedHeap* gch = GenCollectedHeap::heap();
234 if (gch->total_full_collections_completed() <= _full_gc_count_before) { 235 if (_gc_cause != GCCause::_gc_locker &&
236 gch->total_full_collections_completed() <= _full_gc_count_before) {
237 assert(ExplicitGCInvokesConcurrent, "Error");
235 // Now, wait for witnessing concurrent gc cycle to complete, 238 // Now, wait for witnessing concurrent gc cycle to complete,
236 // but do so in native mode, because we want to lock the 239 // but do so in native mode, because we want to lock the
237 // FullGCEvent_lock, which may be needed by the VM thread 240 // FullGCEvent_lock, which may be needed by the VM thread
238 // or by the CMS thread, so we do not want to be suspended 241 // or by the CMS thread, so we do not want to be suspended
239 // while holding that lock. 242 // while holding that lock.