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https://issues.apache.org/jira/browse/HDFS-6591?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14043285#comment-14043285
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Liang Xie commented on HDFS-6591:
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Retry. After a debugging, showed a rare race. the CountDownLatch is inside
Callable, but there's no guarantee: when a countDown happened, then one of
tasks has done. see:
http://stackoverflow.com/questions/9604713/future-isdone-returns-false-even-if-the-task-is-done
. really tricky...
I rewrote the sync related code in the latest patch. and passed all the
TestPread case in a shell loop:)
> while loop is executed tens of thousands of times in Hedged Read
> ------------------------------------------------------------------
>
> Key: HDFS-6591
> URL: https://issues.apache.org/jira/browse/HDFS-6591
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 2.4.0
> Reporter: LiuLei
> Assignee: Liang Xie
> Attachments: HDFS-6591.txt, LoopTooManyTimesTestCase.patch
>
>
> I download hadoop-2.4.1-rc1 code from
> http://people.apache.org/~acmurthy/hadoop-2.4.1-rc1/, I test the Hedged
> Read. I find the while loop in hedgedFetchBlockByteRange method is executed
> tens of thousands of times.
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