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https://issues.apache.org/jira/browse/HELIX-195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13731255#comment-13731255
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Hudson commented on HELIX-195:
------------------------------

SUCCESS: Integrated in helix #1117 (See 
[https://builds.apache.org/job/helix/1117/])
HELIX-195: fix race condition between FINALIZE callbacks and zk callbacks, 
rb=13345 (zzhang: rev 6d5397990d9629009e304ae6eea4a046d5429871)
* helix-core/src/main/java/org/apache/helix/manager/zk/CallbackHandler.java
* 
helix-core/src/main/java/org/apache/helix/manager/zk/DistributedLeaderElection.java
* 
helix-core/src/test/java/org/apache/helix/integration/manager/ClusterDistributedController.java
* 
helix-core/src/main/java/org/apache/helix/manager/zk/ParticipantManagerHelper.java
* 
helix-core/src/main/java/org/apache/helix/controller/GenericHelixController.java
* 
helix-core/src/test/java/org/apache/helix/integration/manager/TestZkCallbackHandlerLeak.java
* helix-core/src/test/java/org/apache/helix/TestHelper.java
* 
helix-core/src/test/java/org/apache/helix/integration/manager/TestConsecutiveZkSessionExpiry.java
* 
helix-core/src/test/java/org/apache/helix/integration/manager/TestControllerManager.java
* 
helix-core/src/main/java/org/apache/helix/manager/zk/DistributedControllerManager.java
* 
helix-core/src/test/java/org/apache/helix/integration/manager/TestParticipantManager.java
* 
helix-core/src/test/java/org/apache/helix/integration/manager/TestDistributedControllerManager.java
* helix-core/src/main/java/org/apache/helix/manager/zk/ParticipantManager.java
* helix-core/src/main/java/org/apache/helix/manager/zk/ControllerManager.java
* helix-core/src/main/java/org/apache/helix/manager/zk/AbstractManager.java

                
> Race condition between FINALIZE callbacks and Zk Callbacks
> ----------------------------------------------------------
>
>                 Key: HELIX-195
>                 URL: https://issues.apache.org/jira/browse/HELIX-195
>             Project: Apache Helix
>          Issue Type: Sub-task
>            Reporter: dafu
>            Assignee: dafu
>
> FINALIZE callbacks are sent async via CallbackHandler#reset(), while Zk 
> callbacks are queued in ZkEventThread. It's possible that we are handling a 
> FINALIZE callback before all Zk callbacks are cleaned up. This creates race 
> conditions, for example, in zk session expiry, when a GenericController gets 
> a FINALIZE callback, it cleans up all listeners using ZkClient#unsubscribe(), 
> but Zk callbacks  leftover in ZkEventThread comes later, and re-subscribe all 
> listeners, causing zk watcher leaking.
> This is observed by setting up two controllers and expire the leader (by 
> simulating a long gc). The second controller takes the leadership and add all 
> listeners, but when the former leader recovers from gc, it gets leftover Zk 
> callbacks and re-subscribe the live-instance listener hence react to all 
> live-instance changes, though it doesn't acquire the leadership.

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