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Posted to common-issues@hadoop.apache.org by "Andrew Wang (JIRA)" <ji...@apache.org> on 2015/07/23 23:33:04 UTC
[jira] [Commented] (HADOOP-12189) improve
CallQueueManager#swapQueue to make queue elements drop nearly impossible.
[ https://issues.apache.org/jira/browse/HADOOP-12189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14639544#comment-14639544 ]
Andrew Wang commented on HADOOP-12189:
--------------------------------------
LGTM too, will commit shortly. Thanks Zhihai for the patch, Chris and Arpit for reviewing.
> improve CallQueueManager#swapQueue to make queue elements drop nearly impossible.
> ---------------------------------------------------------------------------------
>
> Key: HADOOP-12189
> URL: https://issues.apache.org/jira/browse/HADOOP-12189
> Project: Hadoop Common
> Issue Type: Improvement
> Components: ipc, test
> Affects Versions: 2.7.1
> Reporter: zhihai xu
> Assignee: zhihai xu
> Attachments: HADOOP-12189.000.patch, HADOOP-12189.001.patch, HADOOP-12189.none_guarantee.000.patch, HADOOP-12189.none_guarantee.001.patch, HADOOP-12189.none_guarantee.002.patch
>
>
> CallQueueManager may drop elements from the queue sometimes when calling {{swapQueue}}.
> The following test failure from TestCallQueueManager shown some elements in the queue are dropped.
> https://builds.apache.org/job/PreCommit-HADOOP-Build/7150/testReport/org.apache.hadoop.ipc/TestCallQueueManager/testSwapUnderContention/
> {code}
> java.lang.AssertionError: expected:<27241> but was:<27245>
> at org.junit.Assert.fail(Assert.java:88)
> at org.junit.Assert.failNotEquals(Assert.java:743)
> at org.junit.Assert.assertEquals(Assert.java:118)
> at org.junit.Assert.assertEquals(Assert.java:555)
> at org.junit.Assert.assertEquals(Assert.java:542)
> at org.apache.hadoop.ipc.TestCallQueueManager.testSwapUnderContention(TestCallQueueManager.java:220)
> {code}
> It looked like the elements in the queue are dropped due to {{CallQueueManager#swapQueue}}
> Looked at the implementation of {{CallQueueManager#swapQueue}}, there is a possibility that the elements in the queue are dropped. If the queue is full, the calling thread for {{CallQueueManager#put}} is blocked for long time. It may put the element into the old queue after queue in {{takeRef}} is changed by swapQueue, then this element in the old queue will be dropped.
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