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https://issues.apache.org/jira/browse/OOZIE-1722?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13916699#comment-13916699
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Venkat Ranganathan commented on OOZIE-1722:
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bq. If we put the tag in the job itself, then the launcher would try to kill
itself unless we add additional logic to exclude it, but I'm not sure we can do
that easily. I'm also not sure what we'd gain from this; the launcher doesn't
need to find itself and the Oozie server already has the job ID for the
launcher.
I agree that the logic will be a little more than what there is currently
bq. I hadn't considered the affect of this on uber mode. But shouldn't that
not make a difference here? The launcher and action jobs are still separate
jobs so they should have different tags, right?
Right, they will be separate jobs, But when enabling uber mode there were some
failure modes that I hit in secure mode that led me to tagging the launcher
also. We can revisit that when we enable uber mode.
Will run some tests with your patch and let you know.
> When an ApplicationMaster restarts, it restarts the launcher job
> ----------------------------------------------------------------
>
> Key: OOZIE-1722
> URL: https://issues.apache.org/jira/browse/OOZIE-1722
> Project: Oozie
> Issue Type: Improvement
> Affects Versions: trunk
> Reporter: Robert Kanter
> Assignee: Robert Kanter
> Attachments: OOZIE-1722.patch
>
>
> When using Yarn, there are some situations in which the ApplicationMaster can
> be restarted (e.g. RM failover, the AM dies and another attempt is made,
> etc).
> When this happens, it starts the launcher job again, which will start over.
> So, if that launcher has already launched a job, we'll end up with two
> instances of the same job, which can be problematic. For example, if you
> have a Pig action, the Pig client might run a job, but then the launcher gets
> restarted by an AM restart and launches that same job again.
> We don't have a way of "re-attaching" to previously launched jobs; however,
> with YARN-1461 and MAPREDUCE-5699, we can use yarn tags to find anything the
> launcher previously launched that's running and kill them. We still have to
> start over, but at least we're not running two instances of a job at the same
> time.
> Here's what we can do for each action type:
> - Pig, Sqoop, Hive
> -- Kill previously launched jobs and start over
> - MapReduce (different because of the optimization)
> -- Exit launcher if a previously launched job already exists
> - Java, Shell
> -- No out-of-the-box support for this
> -- Like with other things, the Java action can take advantage of this like
> Pig, Sqoop, and Hive if the user adds some code
> - DistCp
> -- Not supported
> - SSH, Email
> -- N/A
> The yarn tags won't be available until Hadoop 2.4.0, but is in the nightly
> (i.e. Hadoop 3.0.0-SNAPSHOT); and its obviously not in Hadoop 1.x. To be
> able to use the Yarn methods and the new methods for tagging, we can add a
> new type of Hadooplib called "Hadoop Utils" where we can put classes that are
> specific to a specific version of Hadoop; the other implementations can have
> dummy versions. For example, in the Hadoop-2 Hadoop Utils, we can put a
> method foo() that calls some yarn stuff but in the Hadoop-1 Hadoop Utils, the
> foo() method would either do the equivalent in MR1 or a no-op. So for now, I
> put some methods in the Hadoop-3 Hadoop Utils that use the tags and the
> Hadoop-1, Hadoop-2, and Hadoop-23 Hadoop Utils all have dummy implementations
> that don't do anything (so the existing behavior is preserved). The Hadoop
> Utils modules will allow us to take advantage of Hadoop 2 only features in
> the future, while still being able to compile against Hadoop 1; so it's not
> just limited to this feature.
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