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https://issues.apache.org/jira/browse/HDFS-16293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17452908#comment-17452908
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Takanobu Asanuma commented on HDFS-16293:
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[~Yuanxin Zhu] Thanks for your explanation and for updating the patch. It seems
the unit test becomes stable, and [^HDFS-16293.06.patch] mostly looks good to
me. Some minor comments:
* Could you add a timeout to the unit test? @Test(timeout=60000)
* Please provide more comments to the unit tests about the purpose of each
thread, and why it verifies that congestedNodes.size() is greater than 1, and
so on.
* How about adding a comment like "// streamer has to release dataQueue before
calling backoff" before calling backOffIfNecessary()?
> Client sleeps and holds 'dataQueue' when DataNodes are congested
> ----------------------------------------------------------------
>
> Key: HDFS-16293
> URL: https://issues.apache.org/jira/browse/HDFS-16293
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 3.2.2, 3.3.1, 3.2.3
> Reporter: Yuanxin Zhu
> Assignee: Yuanxin Zhu
> Priority: Major
> Attachments: HDFS-16293.01-branch-3.2.2.patch, HDFS-16293.01.patch,
> HDFS-16293.02.patch, HDFS-16293.03.patch, HDFS-16293.04.patch,
> HDFS-16293.05.patch, HDFS-16293.06.patch
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> When I open the ECN and use Terasort(500G data,8 DataNodes,76 vcores/DN) for
> testing, DataNodes are congested(HDFS-8008). The client enters the sleep
> state after receiving the ACK for many times, but does not release the
> 'dataQueue'. The ResponseProcessor thread needs the 'dataQueue' to execute
> 'ackQueue.getFirst()', so the ResponseProcessor will wait for the client to
> release the 'dataQueue', which is equivalent to that the ResponseProcessor
> thread also enters sleep, resulting in ACK delay.MapReduce tasks can be
> delayed by tens of minutes or even hours.
> The DataStreamer thread can first execute 'one = dataQueue. getFirst()',
> release 'dataQueue', and then judge whether to execute 'backOffIfNecessary()'
> according to 'one.isHeartbeatPacket()'
>
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