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https://issues.apache.org/jira/browse/HADOOP-12189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14640376#comment-14640376
]
Hudson commented on HADOOP-12189:
---------------------------------
FAILURE: Integrated in Hadoop-Yarn-trunk-Java8 #266 (See
[https://builds.apache.org/job/Hadoop-Yarn-trunk-Java8/266/])
HADOOP-12189. Improve CallQueueManager#swapQueue to make queue elements drop
nearly impossible. Contributed by Zhihai Xu. (wang: rev
6736a1ab7033523ed5f304fdfed46d7f348665b4)
*
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/CallQueueManager.java
* hadoop-common-project/hadoop-common/CHANGES.txt
*
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestCallQueueManager.java
> 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
> Fix For: 2.8.0
>
> 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
>
>
> Improve CallQueueManager#swapQueue to make queue elements drop nearly
> impossible. This is the trade-off between performance and functionality, even
> in the very very rare situation, we may drop one element, but it is not the
> end of the world since the client may still recover with timeout.
> 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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