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https://issues.apache.org/jira/browse/HBASE-14370?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14735423#comment-14735423
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Enis Soztutar commented on HBASE-14370:
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Forking a thread is expensive, so we do not use that pattern but instead use
Executors with fixed thread pools. Plus, as mentioned above, we have to make
sure that the refresh requests from different even notifications should execute
in the same order that the zk notification comes from. Single threaded executor
should be able to do that.
> Use separate thread for calling ZKPermissionWatcher#refreshNodes()
> ------------------------------------------------------------------
>
> Key: HBASE-14370
> URL: https://issues.apache.org/jira/browse/HBASE-14370
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.98.0
> Reporter: Ted Yu
> Assignee: Ted Yu
> Attachments: 14370-v1.txt
>
>
> I came off a support case (0.98.0) where main zk thread was seen doing the
> following:
> {code}
> at
> org.apache.hadoop.hbase.security.access.ZKPermissionWatcher.refreshAuthManager(ZKPermissionWatcher.java:152)
> at
> org.apache.hadoop.hbase.security.access.ZKPermissionWatcher.refreshNodes(ZKPermissionWatcher.java:135)
> at
> org.apache.hadoop.hbase.security.access.ZKPermissionWatcher.nodeChildrenChanged(ZKPermissionWatcher.java:121)
> at
> org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.process(ZooKeeperWatcher.java:348)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
> {code}
> There were 62000 nodes under /acl due to lack of fix from HBASE-12635,
> leading to slowness in table creation because zk notification for region
> offline was blocked by the above.
> The attached patch separates refreshNodes() call into its own thread.
> Thanks to Enis and Devaraj for offline discussion.
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