Blocker Description
I just hit this while working on an elasticseach test using a lucene 5.1 snapshot (5.1.0-snapshot-1654549). The test throws random exceptions via MockDirWrapper and deadlocks, jstack says:
Found one Java-level deadlock: ============================= "elasticsearch[node_2][refresh][T#2]": waiting to lock monitor 0x00007fe51314c098 (object 0x00000007018ee8d8, a java.lang.Object), which is held by "elasticsearch[node_2][generic][T#1]" "elasticsearch[node_2][generic][T#1]": waiting to lock monitor 0x00007fe512d74b68 (object 0x00000007018ee8e8, a java.lang.Object), which is held by "elasticsearch[node_2][refresh][T#2]" Java stack information for the threads listed above: =================================================== "elasticsearch[node_2][refresh][T#2]": at org.apache.lucene.index.IndexWriter.tragicEvent(IndexWriter.java:4441) - waiting to lock <0x00000007018ee8d8> (a java.lang.Object) at org.apache.lucene.index.IndexWriter.getReader(IndexWriter.java:436) - locked <0x00000007018ee8e8> (a java.lang.Object) at org.apache.lucene.index.StandardDirectoryReader.doOpenFromWriter(StandardDirectoryReader.java:281) at org.apache.lucene.index.StandardDirectoryReader.doOpenIfChanged(StandardDirectoryReader.java:256) at org.apache.lucene.index.StandardDirectoryReader.doOpenIfChanged(StandardDirectoryReader.java:246) at org.apache.lucene.index.FilterDirectoryReader.doOpenIfChanged(FilterDirectoryReader.java:104) at org.apache.lucene.index.DirectoryReader.openIfChanged(DirectoryReader.java:123) at org.apache.lucene.search.SearcherManager.refreshIfNeeded(SearcherManager.java:137) at org.apache.lucene.search.SearcherManager.refreshIfNeeded(SearcherManager.java:58) at org.apache.lucene.search.ReferenceManager.doMaybeRefresh(ReferenceManager.java:176) at org.apache.lucene.search.ReferenceManager.maybeRefreshBlocking(ReferenceManager.java:253) at org.elasticsearch.index.engine.internal.InternalEngine.refresh(InternalEngine.java:703) at org.elasticsearch.index.shard.IndexShard.refresh(IndexShard.java:500) at org.elasticsearch.index.shard.IndexShard$EngineRefresher$1.run(IndexShard.java:954) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745) "elasticsearch[node_2][generic][T#1]": at org.apache.lucene.index.IndexWriter.prepareCommitInternal(IndexWriter.java:2730) - waiting to lock <0x00000007018ee8e8> (a java.lang.Object) - locked <0x00000007018ee8d8> (a java.lang.Object) at org.apache.lucene.index.IndexWriter.commitInternal(IndexWriter.java:2888) - locked <0x00000007018ee8d8> (a java.lang.Object) at org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:2855) at org.elasticsearch.index.engine.internal.InternalEngine.commitIndexWriter(InternalEngine.java:722) at org.elasticsearch.index.engine.internal.InternalEngine.flush(InternalEngine.java:800) at org.elasticsearch.index.engine.internal.InternalEngine$RecoveryCounter.endRecovery(InternalEngine.java:1520) at org.elasticsearch.index.engine.internal.InternalEngine$RecoveryCounter.close(InternalEngine.java:1533) at org.elasticsearch.common.lease.Releasables.close(Releasables.java:45) at org.elasticsearch.common.lease.Releasables.closeWhileHandlingException(Releasables.java:70) at org.elasticsearch.common.lease.Releasables.closeWhileHandlingException(Releasables.java:75) at org.elasticsearch.index.engine.internal.InternalEngine.recover(InternalEngine.java:1048) at org.elasticsearch.index.shard.IndexShard.recover(IndexShard.java:635) at org.elasticsearch.indices.recovery.RecoverySource.recover(RecoverySource.java:120) at org.elasticsearch.indices.recovery.RecoverySource.access$200(RecoverySource.java:48) at org.elasticsearch.indices.recovery.RecoverySource$StartRecoveryTransportRequestHandler.messageReceived(RecoverySource.java:141) at org.elasticsearch.indices.recovery.RecoverySource$StartRecoveryTransportRequestHandler.messageReceived(RecoverySource.java:127) at org.elasticsearch.transport.local.LocalTransport$2.doRun(LocalTransport.java:287) at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:36) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745) Found 1 deadlock.