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From "Jason Lowe (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4774) repair test org.apache.hadoop.mapred.TestClusterMRNotification.testMR
Date Thu, 08 Nov 2012 16:22:12 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13493279#comment-13493279

Jason Lowe commented on MAPREDUCE-4774:

Thanks for the analysis, Ivan!  JobImpl's state machine is missing a number of events in the
FAILED state.  Due to the asynchronous nature of the job, task, and task attempt state machines,
it is possible for tasks and task attempts to complete even though the job overall has decided
to fail for other reasons.  Therefore we need to ignore these additional events in the FAILED
state to avoid their asynchronous arrival from knocking us out of the FAILED state and into
the ERROR state.


> 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 
> https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/2982//testReport/org.apache.hadoop.mapred/TestClusterMRNotification/testMR/).
> 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
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:
> http://localhost:48656/notification/mapred?jobId=job_1352199715842_0002&amp;jobStatus=ERROR

> (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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