zhihai xu created HADOOP-12189:
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Summary: 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
Affects Versions: 2.7.1
Reporter: zhihai xu
Assignee: zhihai xu
CallQueueManager may drop elements from the queue sometimes when calling
{{swapQueue}}.
The following test failure 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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