[jira] Commented: (HBASE-1111) [performance] Crash recovery takes way too long

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

    [ https://issues.apache.org/jira/browse/HBASE-1111?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12662191#action_12662191 ] 

stack commented on HBASE-1111:
------------------------------

Yeah, just tried killing server that was carrying -ROOT-.  Took 20 minutes just processing 41 log files.  All clients were  dead by time cluster was again useable.

> [performance] Crash recovery takes way too long
> -----------------------------------------------
>
>                 Key: HBASE-1111
>                 URL: https://issues.apache.org/jira/browse/HBASE-1111
>             Project: Hadoop HBase
>          Issue Type: Improvement
>            Reporter: stack
>
> Watching hbase recover from crashes, its taking way too long:
> 1. Must wait first on lease to expire (if server is rebooted, it should cancel the old servers' lease but make sure the lease expiration code runs)
> 2. Master splits logs.  This is single-threaded.  At least a maximum of 64 logs but seems to run slow anyways.
> 3. Assign out the regions that were on dead-server (minutes or even tens of minutes could have elapsed at this stage)
> 4. Wait on the regionservers to open.  If small cluster, because regionservers open regions in series, could take a long time opening a bunch of issues.  Meantime the regions are not available, clients will likely timeout.
> 5. To make things worse, I've seen load-balancer cut in to 'help out' telling regionserver close some of its regions though its busy opening a bunch.
> Andrew Purtell notes that HBASE-1110 will change a bunch of the above.

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