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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11208) Remove the hbase.hstor.blockingStoreFiles setting
Date Tue, 20 May 2014 17:06:38 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14003641#comment-14003641
] 

Lars Hofhansl commented on HBASE-11208:
---------------------------------------

Whoa... This is the one mechanism HBase has to limit writes when writes come in faster than
the hardware (the IO system) can absorb. The only other mechanism is OOM'ing.
How else do you purpose throttling clients?

> Remove the hbase.hstor.blockingStoreFiles setting
> -------------------------------------------------
>
>                 Key: HBASE-11208
>                 URL: https://issues.apache.org/jira/browse/HBASE-11208
>             Project: HBase
>          Issue Type: Brainstorming
>          Components: Compaction, regionserver
>    Affects Versions: 0.99.0
>            Reporter: Nicolas Liochon
>            Assignee: Nicolas Liochon
>             Fix For: 0.99.0
>
>
> It's a little bit of a provocation, but the rational is:
>  - there are some bugs around the delayed flush. For example, if the periodic scheduler
has asked for a delayed flush, and that we need to flush, we will have to wait
>  - if the number of WAL files increases, we won't flush immediately if the blockingFile
number has been reached. This impacts the MTTR.
>  - We don't write to limit the compaction impact, but they are many cases where we would
want to flush anyway, as the writes cannot wait.
>  - this obviously leads to huge write latency peaks.
> So I'm questioning this setting, it leads to multiple intricate cases, unpredictable
write latency, and looks like a workaround for compaction performances. With all the work
done on compaction, I think we can get rid of it.  A solution in the middle would be to deprecate
it and to set it to a large value...
> Any opinion before I shoot :-) ? 



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