[jira] [Commented] (HBASE-8483) HConnectionManager can leak ZooKeeper connections when using deleteStaleConnection

["Eric Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-8483?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13648324#comment-13648324 ] 

Eric Yu commented on HBASE-8483:
--------------------------------

I switched to using createConnection and sharing that connection across multiple threads, but still ran into possible ZK connection leaks if I closed the connection while others threads were using it. So far I can only avoid the problem by putting a check in ConnectionManager.HConnectionImplementation.getZooKeeperWatcher to not create a watcher if the hconnection is already closed and synchronize in HConnectionImplementation.close(boolean) when it is closing zk watcher and setting the closed indicator to true. Of course, the leak doesn't occur very much because application doesn't call deleteStaleConnection very often, only when we think the connection has problems. And the leak doesn't occur every time we close, only if another thread creates a new watcher after the hconnection has been closed.
                
> HConnectionManager can leak ZooKeeper connections when using deleteStaleConnection
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-8483
>                 URL: https://issues.apache.org/jira/browse/HBASE-8483
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 0.94.4
>            Reporter: Eric Yu
>            Priority: Critical
>             Fix For: 0.95.1
>
>         Attachments: LeakZKConnections.java
>
>
> If one thread calls deleteStaleConnection while other threads are using connection, can leak ZK connections.

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