[jira] [Created] (HDFS-10816) TestComputeInvalidateWork#testDatanodeReRegistration fails due to race between test and replication monitor

["Eric Badger (JIRA)" <ji...@apache.org>]

Eric Badger created HDFS-10816:
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             Summary: TestComputeInvalidateWork#testDatanodeReRegistration fails due to race between test and replication monitor
                 Key: HDFS-10816
                 URL: https://issues.apache.org/jira/browse/HDFS-10816
             Project: Hadoop HDFS
          Issue Type: Bug
            Reporter: Eric Badger
            Assignee: Eric Badger


{noformat}
java.lang.AssertionError: Expected invalidate blocks to be the number of DNs expected:<3> but was:<2>
	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.apache.hadoop.hdfs.server.blockmanagement.TestComputeInvalidateWork.testDatanodeReRegistration(TestComputeInvalidateWork.java:160)
{noformat}

The test fails because of a race condition between the test and the replication monitor. The default replication monitor interval is 3 seconds, which is just about how long the test normally takes to run. The test deletes a file and then subsequently gets the namesystem writelock. However, if the replication monitor fires in between those two instructions, the test will fail as it will itself invalidate one of the blocks. This can be easily reproduced by removing the sleep() in the ReplicationMonitor's run() method in BlockManager.java, so that the replication monitor executes as quickly as possible and exacerbates the race. 

To fix the test all that needs to be done is to turn off the replication monitor. 



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