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https://issues.apache.org/jira/browse/HBASE-6466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13476597#comment-13476597
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Kannan Muthukkaruppan commented on HBASE-6466:
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Chunhui wrote: <<<I agree with one flush thread is enough in most case, however
we have encountered the case that memstore always at the global limit in the
online application, the small affect is writing will be blocked sometimes and
the serious affect is jvm would always do CMS if your configuration is not very
appropriate>>>. See description in HBASE-6980. I think for some use cases, the
wins will be substantial. Also, if we do multiple commit logs per server, then
too, this feature will be important to maximize throughput.
> Enable multi-thread for memstore flush
> --------------------------------------
>
> Key: HBASE-6466
> URL: https://issues.apache.org/jira/browse/HBASE-6466
> Project: HBase
> Issue Type: Improvement
> Reporter: chunhui shen
> Assignee: chunhui shen
> Attachments: HBASE-6466.patch, HBASE-6466v2.patch, HBASE-6466v3.patch
>
>
> If the KV is large or Hlog is closed with high-pressure putting, we found
> memstore is often above the high water mark and block the putting.
> So should we enable multi-thread for Memstore Flush?
> Some performance test data for reference,
> 1.test environment ：
> random writting；upper memstore limit 5.6GB;lower memstore limit 4.8GB;400
> regions per regionserver；row len=50 bytes, value len=1024 bytes;5
> regionserver, 300 ipc handler per regionserver;5 client, 50 thread handler
> per client for writing
> 2.test results:
> one cacheFlush handler, tps: 7.8k/s per regionserver, Flush:10.1MB/s per
> regionserver, appears many aboveGlobalMemstoreLimit blocking
> two cacheFlush handlers, tps: 10.7k/s per regionserver, Flush:12.46MB/s per
> regionserver,
> 200 thread handler per client & two cacheFlush handlers, tps:16.1k/s per
> regionserver, Flush:18.6MB/s per regionserver
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