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https://issues.apache.org/jira/browse/TEZ-3958?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16522585#comment-16522585
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Jaume M commented on TEZ-3958:
------------------------------
[~gopalv] looking at the code seems like the priority is something task
specific, not vertex specific. Also it looks like we [determine this when
scheduling the
tasks|https://github.com/apache/tez/blob/3f2373e2b2ab3825ef50e9f19b8704265542a8b2/tez-dag/src/main/java/org/apache/tez/dag/app/dag/impl/TaskAttemptImpl.java#L1323]
and we generate the {{dag.dot}} when the DAG is submitted so the best thing
we'd be able to log at that point is an estimation of the priority of the task.
> Add internal vertex priority information into the tez dag.dot debug
> information
> -------------------------------------------------------------------------------
>
> Key: TEZ-3958
> URL: https://issues.apache.org/jira/browse/TEZ-3958
> Project: Apache Tez
> Issue Type: Improvement
> Reporter: Gopal V
> Priority: Major
>
> Adding the actual vertex priority as computed by Tez into the debug dag.dot
> file would allows the debugging of task pre-emption issues when the DAG is no
> longer a tree.
> There are pre-emption issues with isomerization of Tez DAGs, where the a
> R-isomer dag with mirror rotation runs at a different speed than the L-isomer
> dag, due to priorities at the same level changing due to the vertex-id order.
> Since the problem is hard to debug through, it would be good to record the
> computed priority in the DAG .dot file in the logging directories.
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