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https://issues.apache.org/jira/browse/HBASE-6466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13972817#comment-13972817
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Liu Shaohui commented on HBASE-6466:
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[~zjushch]
Very curious about this patch.
In current codebase, the write of hlog is many small pieces write and sync,
and the flush of memstore are batch write. So i think the throughput of one
-thread flush is larger than the throughput of write of hlog. That means one
flush thread is enough for most cases.
What's scenario for multi-thread memstore flush? High-throughput write without
wal?
> Enable multi-thread for memstore flush
> --------------------------------------
>
> Key: HBASE-6466
> URL: https://issues.apache.org/jira/browse/HBASE-6466
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Affects Versions: 0.95.2
> Reporter: chunhui shen
> Assignee: chunhui shen
> Priority: Critical
> Fix For: 0.95.0
>
> Attachments: 6466-v6.patch, 6466-v7.patch, HBASE-6466-v4.patch,
> HBASE-6466-v4.patch, HBASE-6466-v5.patch, HBASE-6466.patch,
> HBASE-6466v2.patch, HBASE-6466v3.1.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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