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https://issues.apache.org/jira/browse/HDFS-5776?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13906611#comment-13906611
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Liang Xie commented on HDFS-5776:
---------------------------------
Huge thanks, [~saint....@gmail.com] ! Here is the YCSB test result w/ the
latest v21 patch:
My test env, setting, data just same as the previous ones.
hedged read thread pool size = 0:
{code}
[OVERALL], Throughput(ops/sec), 248.69758063844773
[READ], AverageLatency(us), 40152.776944654586
[READ], 50thPercentileLatency(us), 21023
[READ], 95thPercentileLatency(us), 151130
[READ], 99thPercentileLatency(us), 255973
[READ], 99.9thPercentileLatency(us), 420971
{code}
hedged read thread pool size = 50, hedged read timeout = 250ms :
{code}
[OVERALL], Throughput(ops/sec), 231.90953643421446
[READ], AverageLatency(us), 43094.41323982726
[READ], 50thPercentileLatency(us), 23280
[READ], 95thPercentileLatency(us), 160024
[READ], 99thPercentileLatency(us), 258110
[READ], 99.9thPercentileLatency(us), 278328
{code}
hedged read thread pool size = 50, hedged read timeout = 150ms :
{code}
[OVERALL], Throughput(ops/sec), 240.76033437917079
[READ], AverageLatency(us), 41507.364070480435
[READ], 50thPercentileLatency(us), 23316
[READ], 95thPercentileLatency(us), 158907
[READ], 99thPercentileLatency(us), 168504
[READ], 99.9thPercentileLatency(us), 218926
{code}
hedged read thread pool size = 50, hedged read timeout = 100ms :
{code}
[OVERALL], Throughput(ops/sec), 271.0941444451295
[READ], AverageLatency(us), 36863.66854547243
[READ], 50thPercentileLatency(us), 21371
[READ], 95thPercentileLatency(us), 114943
[READ], 99thPercentileLatency(us), 121673
[READ], 99.9thPercentileLatency(us), 195467
{code}
> Support 'hedged' reads in DFSClient
> -----------------------------------
>
> Key: HDFS-5776
> URL: https://issues.apache.org/jira/browse/HDFS-5776
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client
> Affects Versions: 3.0.0
> Reporter: Liang Xie
> Assignee: Liang Xie
> Attachments: HDFS-5776-v10.txt, HDFS-5776-v11.txt, HDFS-5776-v12.txt,
> HDFS-5776-v12.txt, HDFS-5776-v13.wip.txt, HDFS-5776-v14.txt,
> HDFS-5776-v15.txt, HDFS-5776-v17.txt, HDFS-5776-v17.txt, HDFS-5776-v2.txt,
> HDFS-5776-v3.txt, HDFS-5776-v4.txt, HDFS-5776-v5.txt, HDFS-5776-v6.txt,
> HDFS-5776-v7.txt, HDFS-5776-v8.txt, HDFS-5776-v9.txt, HDFS-5776.txt,
> HDFS-5776v18.txt, HDFS-5776v21.txt
>
>
> This is a placeholder of hdfs related stuff backport from
> https://issues.apache.org/jira/browse/HBASE-7509
> The quorum read ability should be helpful especially to optimize read outliers
> we can utilize "dfs.dfsclient.quorum.read.threshold.millis" &
> "dfs.dfsclient.quorum.read.threadpool.size" to enable/disable the hedged read
> ability from client side(e.g. HBase), and by using DFSQuorumReadMetrics, we
> could export the interested metric valus into client system(e.g. HBase's
> regionserver metric).
> The core logic is in pread code path, we decide to goto the original
> fetchBlockByteRange or the new introduced fetchBlockByteRangeSpeculative per
> the above config items.
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