Tom Byrne created CURATOR-172:
---------------------------------
Summary: 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.
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