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