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https://issues.apache.org/jira/browse/HBASE-3719?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14261284#comment-14261284
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Sean Busbey commented on HBASE-3719:
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client request to those regions that share the WAL that is rolling will wait,
yes. I don't think we actually need to wait for the log close though, provided
we had waited for a sync (that is, our persistence promise is already met at
sync time).
One of the suggestions I've seen in connection with HBASE-10278 is to always
use a hot spare HDFS pipeline to do the rolling. I think that's a great idea
and we could combine it with having a worker handle the closing outside of the
critical section. That should go a long way to minimizing how much of a time
hit clients take at roll time.
> Workload has to drain before hlog can be rolled
> -----------------------------------------------
>
> Key: HBASE-3719
> URL: https://issues.apache.org/jira/browse/HBASE-3719
> Project: HBase
> Issue Type: Improvement
> Components: regionserver, wal
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> In the current implementation, the regionserver blocks new transactions from
> occuring when the HLog is rolled. Closing the existing HLog sometimes takes
> more than a few seconds and during this time all new puts/increments are
> blocked. It will be nice if we can continue to write new transactions to the
> new HLog (but maybe not commit those transactions) while the old HLog is
> being closed.
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