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From "Ivan A. Veselovsky (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-4774) repair test org.apache.hadoop.mapred.TestClusterMRNotification.testMR
Date Tue, 06 Nov 2012 11:30:12 GMT
Ivan A. Veselovsky created MAPREDUCE-4774:

             Summary: repair test org.apache.hadoop.mapred.TestClusterMRNotification.testMR
                 Key: MAPREDUCE-4774
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4774
             Project: Hadoop Map/Reduce
          Issue Type: Bug
            Reporter: Ivan A. Veselovsky

The test org.apache.hadoop.mapred.TestClusterMRNotification.testMR frequently  fails in mapred
build (e.g. see https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/2988/testReport/junit/org.apache.hadoop.mapred/TestClusterMRNotification/testMR/
, or 

The test aims to check Job status notifications received through HTTP Servlet. It runs 3 jobs:
successfull, killed, and failed. 
The test expects the servlet to receive some expected notifications in some expected order.
It also tries to test the retry-on-failure notification functionality, so on each 1st notification
the servlet answers "400 forcing error", and on each 2nd notification attempt it answers "ok".

In general, the test fails because the actual number and/or type of the notifications differs
from the expected.

Investigation shows that actual root cause of the problem is an incorrect job state transition:
the 3rd job mapred task fails (by intentionally thrown  RuntimeException, see UtilsForTests#runJobFail()),
and the state of the task changes from RUNNING to FAILED.
At this point JobEventType.JOB_TASK_ATTEMPT_COMPLETED event is submitted (in  method org.apache.hadoop.mapreduce.v2.app.job.impl.TaskImpl.handleTaskAttemptCompletion(TaskAttemptId,
TaskAttemptCompletionEventStatus)), and this event gets processed in AsyncDispatcher, but
this transition is impossible according to the event transition map (see org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl#stateMachineFactory).
This causes the following exception to be thrown upon the event processing:
2012-11-06 12:22:02,335 ERROR [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl:
Can't handle this event at current state
org.apache.hadoop.yarn.state.InvalidStateTransitonException: Invalid event: JOB_TASK_ATTEMPT_COMPLETED
        at org.apache.hadoop.yarn.state.StateMachineFactory.doTransition(StateMachineFactory.java:309)
        at org.apache.hadoop.yarn.state.StateMachineFactory.access$3(StateMachineFactory.java:290)
        at org.apache.hadoop.yarn.state.StateMachineFactory$InternalStateMachine.doTransition(StateMachineFactory.java:454)
        at org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.handle(JobImpl.java:716)
        at org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.handle(JobImpl.java:1)
        at org.apache.hadoop.mapreduce.v2.app.MRAppMaster$JobEventDispatcher.handle(MRAppMaster.java:917)
        at org.apache.hadoop.mapreduce.v2.app.MRAppMaster$JobEventDispatcher.handle(MRAppMaster.java:1)
        at org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:130)
        at org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:79)
        at java.lang.Thread.run(Thread.java:662) 

So, the job gets into state "INTERNAL_ERROR", the job end notification like this is sent:

(here we can see "ERROR" status instead of "FAILED")
After that the notification servlet receives either only "ERROR" notification, or one more
notification "ERROR" after "FAILED", which finally causes the test to fail. (Some variation
in the test behavior caused by racing conditions because there are many asynchronous processings
there, and the test is flaky, in fact).

In any way, it looks like the root cause of the problem is the possibility of the forbidden
transition "Invalid event: JOB_TASK_ATTEMPT_COMPLETED at FAILED". 
Need an expert advice on how that should be fixed.

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