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https://issues.apache.org/jira/browse/HBASE-9467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13762037#comment-13762037
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Nicolas Liochon commented on HBASE-9467:
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It's not fully a duplicate, as this one is about ensuring that a workload of a
region does not impact the others. HBASE-8836 concentrates the writers, freeing
resources for the reader. But an heavy write on a region would block the others.
In any case, if you have a fixed number of worker thread, the activity of
someone in the system can block the others (vs. only slowing them).
There is no definitive solutions for this (if it's slow and you add queries it
will become slower: like it or not, the regionserver shares its resources
between all clients, and the load of a region impacts the others). I tend to
think that priorities are the best option.
> 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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