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https://issues.apache.org/jira/browse/HBASE-9467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13764082#comment-13764082
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Feng Honghua commented on HBASE-9467:
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I like [~tlipcon]'s idea that we reject write by RegionOverloadedException
rather than blocking writes. This treatment can also avoid the unnecessary
scenario where RS eventually finishes the write after the memstore flush is
done but client gets timeout response if memstore flush takes too long
But the client receiving such exception can only perform backoff for writes
with the same rowKey as which is responsed such exception, hence can't prevent
writes with different rowKeys belonging to the same region from hitting the RS
and get RegionOverloadedException as well (considering client typically is
unaware of the region key range when doing write)
> write can be totally blocked temporarily by a write-heavy region
> ----------------------------------------------------------------
>
> Key: HBASE-9467
> URL: https://issues.apache.org/jira/browse/HBASE-9467
> Project: HBase
> Issue Type: Improvement
> Reporter: Feng Honghua
> Priority: Minor
>
> Write to a region can be blocked temporarily if the memstore of that region
> reaches the threshold(hbase.hregion.memstore.block.multiplier *
> hbase.hregion.flush.size) until the memstore of that region is flushed.
> For a write-heavy region, if its write requests saturates all the handler
> threads of that RS when write blocking for that region occurs, requests of
> other regions/tables to that RS also can't be served due to no available
> handler threads...until the pending writes of that write-heavy region are
> served after the flush is done. Hence during this time period, from the RS
> perspective it can't serve any request from any table/region just due to a
> single write-heavy region.
> This sounds not very reasonable, right? Maybe write requests from a region
> can only be served by a sub-set of the handler threads, and then write
> blocking of any single region can't lead to the scenario mentioned above?
> Comment?
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