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Kevin Scott Carr commented on CURATOR-172: ------------------------------------------ I believe this can be closed, as there seems to have been an issue with implementation instead of code. > Deadlock when performing background operation > --------------------------------------------- > > Key: CURATOR-172 > URL: https://issues.apache.org/jira/browse/CURATOR-172 > Project: Apache Curator > Issue Type: Bug > Components: Client > Affects Versions: 2.4.2 > Environment: Linux HOSTNAME-REMOVED 2.6.32-279.19.1.el6.x86_64 #1 SMP > Tue Dec 18 15:04:44 PST 2012 x86_64 x86_64 x86_64 GNU/Linux > java version "1.7.0_60" > Java(TM) SE Runtime Environment (build 1.7.0_60-b19) > Java HotSpot(TM) 64-Bit Server VM (build 24.60-b09, mixed mode) > Reporter: Tom Byrne > > Had a box get into a state where our ZK connections were all deadlocked, > waiting on an object monitor. jstack shows that our background thread that > was creating a node was waiting on a lock that was held by the > CuratorFramework thread, who was waiting on an object monitor that looks like > it couldn't be completed until our other write was finished (packet.finish > would never return true.) > We have seen this happen twice, but don't notice it until afterwards, and > don't have enough logging to know what's triggering it (possible ZK > connections going away?) > Rest of the box is fine, network connections are not flapping, main IO > threads continue to accept and process connections, until we get backed up > waiting for ZK. > Here are the two stack traces: > "ZooChangeWatcher-BackgroundReader--2-1-SendThread()" daemon prio=10 > tid=0x00007fcf64108000 nid=0x88d waiting for monitor entry > [0x00007fcbf5d16000] > java.lang.Thread.State: BLOCKED (on object monitor) > at > org.apache.curator.ConnectionState.checkTimeouts(ConnectionState.java:177) > - waiting to lock <0x00000000d526bcc8> (a > org.apache.curator.ConnectionState) > at > org.apache.curator.ConnectionState.getZooKeeper(ConnectionState.java:88) > at > org.apache.curator.CuratorZookeeperClient.getZooKeeper(CuratorZookeeperClient.java:115) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.performBackgroundOperation(CuratorFrameworkImpl.java:763) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.processBackgroundOperation(CuratorFrameworkImpl.java:470) > at > org.apache.curator.framework.imps.CreateBuilderImpl.pathInBackground(CreateBuilderImpl.java:648) > at > org.apache.curator.framework.imps.CreateBuilderImpl.forPath(CreateBuilderImpl.java:427) > at > org.apache.curator.framework.imps.CreateBuilderImpl.forPath(CreateBuilderImpl.java:44) > at > org.apache.curator.framework.recipes.nodes.PersistentEphemeralNode.createNode(PersistentEphemeralNode.java:340) > at > org.apache.curator.framework.recipes.nodes.PersistentEphemeralNode.access$000(PersistentEphemeralNode.java:52) > at > org.apache.curator.framework.recipes.nodes.PersistentEphemeralNode$4.processResult(PersistentEphemeralNode.java:224) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.sendToBackgroundCallback(CuratorFrameworkImpl.java:686) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.checkBackgroundRetry(CuratorFrameworkImpl.java:659) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.processBackgroundOperation(CuratorFrameworkImpl.java:479) > at > org.apache.curator.framework.imps.CreateBuilderImpl.sendBackgroundResponse(CreateBuilderImpl.java:526) > at > org.apache.curator.framework.imps.CreateBuilderImpl.access$600(CreateBuilderImpl.java:44) > at > org.apache.curator.framework.imps.CreateBuilderImpl$6.processResult(CreateBuilderImpl.java:485) > at > org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:602) > at > org.apache.zookeeper.ClientCnxn$EventThread.queuePacket(ClientCnxn.java:475) > - locked <0x00000000fa8e16f8> (a > java.util.concurrent.LinkedBlockingQueue) > at org.apache.zookeeper.ClientCnxn.finishPacket(ClientCnxn.java:627) > at org.apache.zookeeper.ClientCnxn.conLossPacket(ClientCnxn.java:645) > at org.apache.zookeeper.ClientCnxn.access$2400(ClientCnxn.java:85) > at > org.apache.zookeeper.ClientCnxn$SendThread.cleanup(ClientCnxn.java:1160) > - locked <0x00000000fa8e1380> (a java.util.LinkedList) > at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1109) > "CuratorFramework-0" daemon prio=10 tid=0x00007fd02cb57800 nid=0x4425 in > Object.wait() [0x00007fcfc507e000] > java.lang.Thread.State: WAITING (on object monitor) > at java.lang.Object.wait(Native Method) > at java.lang.Object.wait(Object.java:503) > at org.apache.zookeeper.ClientCnxn.submitRequest(ClientCnxn.java:1309) > - locked <0x00000000fa8e6750> (a org.apache.zookeeper.ClientCnxn$Packet) > at org.apache.zookeeper.ClientCnxn.close(ClientCnxn.java:1281) > at org.apache.zookeeper.ZooKeeper.close(ZooKeeper.java:677) > - locked <0x00000000fa8e0948> (a org.apache.zookeeper.ZooKeeper) > at org.apache.curator.HandleHolder.internalClose(HandleHolder.java:139) > at org.apache.curator.HandleHolder.closeAndReset(HandleHolder.java:77) > at org.apache.curator.ConnectionState.reset(ConnectionState.java:218) > - locked <0x00000000d526bcc8> (a org.apache.curator.ConnectionState) > at > org.apache.curator.ConnectionState.checkTimeouts(ConnectionState.java:194) > - locked <0x00000000d526bcc8> (a org.apache.curator.ConnectionState) > at > org.apache.curator.ConnectionState.getZooKeeper(ConnectionState.java:88) > at > org.apache.curator.CuratorZookeeperClient.getZooKeeper(CuratorZookeeperClient.java:115) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.performBackgroundOperation(CuratorFrameworkImpl.java:763) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.backgroundOperationsLoop(CuratorFrameworkImpl.java:749) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl.access$300(CuratorFrameworkImpl.java:56) > at > org.apache.curator.framework.imps.CuratorFrameworkImpl$3.call(CuratorFrameworkImpl.java:244) > at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) > at java.util.concurrent.FutureTask.run(FutureTask.java:166) > at > java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) > at > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) > at java.lang.Thread.run(Thread.java:722) > Help me Obi-Wan Kenobi, you're my only hope. -- This message was sent by Atlassian JIRA (v6.3.4#6332)