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https://issues.apache.org/jira/browse/HBASE-6466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13438360#comment-13438360
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Jimmy Xiang commented on HBASE-6466:
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Instead of having multiple flush threads, can we flush multiple regions each
time when under memory pressure?
For flush thread, one is enough in most case. Multiple threads complicate
things. If under global memory pressure,
we can figure out how many regions to flush based on a configurable ratio of
memory to release.
> 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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