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https://issues.apache.org/jira/browse/HADOOP-12189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14617186#comment-14617186
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zhihai xu commented on HADOOP-12189:
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I uploaded a new patch HADOOP-12189.001.patch. I did some optimization in the
new patch.
With the new patch, the performance is much better. it can process 377,932
elements in less than 297ms using 120 threads for put and 120 threads for take.
The performance with the new patch is very close to the performance without
patch, less than 15% difference.
> CallQueueManager may drop elements from the queue sometimes when calling
> swapQueue
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-12189
> URL: https://issues.apache.org/jira/browse/HADOOP-12189
> Project: Hadoop Common
> Issue Type: Bug
> Components: ipc, test
> Affects Versions: 2.7.1
> Reporter: zhihai xu
> Assignee: zhihai xu
> Attachments: HADOOP-12189.000.patch, HADOOP-12189.001.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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