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Posted to issues@hbase.apache.org by "Jimmy Xiang (Assigned) (JIRA)" <ji...@apache.org> on 2011/12/28 20:22:30 UTC
[jira] [Assigned] (HBASE-5099) ZK event thread waiting for root
region while server shutdown handler waiting for event thread to finish
distributed log splitting to recover the region sever the root region is on
[ https://issues.apache.org/jira/browse/HBASE-5099?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jimmy Xiang reassigned HBASE-5099:
----------------------------------
Assignee: Jimmy Xiang
> ZK event thread waiting for root region while server shutdown handler waiting for event thread to finish distributed log splitting to recover the region sever the root region is on
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-5099
> URL: https://issues.apache.org/jira/browse/HBASE-5099
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.92.0, 0.94.0
> Reporter: Jimmy Xiang
> Assignee: Jimmy Xiang
> Attachments: ZK-event-thread-waiting-for-root.png, distributed-log-splitting-hangs.png, hbase-5099.patch
>
>
> A RS died. The ServerShutdownHandler kicked in and started the logspliting. SpliLogManager
> installed the tasks asynchronously, then started to wait for them to complete.
> The task znodes were not created actually. The requests were just queued.
> At this time, the zookeeper connection expired. HMaster tried to recover the expired ZK session.
> During the recovery, a new zookeeper connection was created. However, this master became the
> new master again. It tried to assign root and meta.
> Because the dead RS got the old root region, the master needs to wait for the log splitting to complete.
> This waiting holds the zookeeper event thread. So the async create split task is never retried since
> there is only one event thread, which is waiting for the root region assigned.
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