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https://issues.apache.org/jira/browse/TEZ-1539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14131135#comment-14131135
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Hitesh Shah commented on TEZ-1539:
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[~bikassaha] Good catch. Yes - the patch does need to change. Storing at the
destination would not work as there is no guarantee that the events were all
captured.
Which reminds me, [~sseth], I am assuming that if a task attempt generates
events and fails, the next attempt's events will override the previous attempt?
> Allow a FIRE_ONCE_ON_SUCCESS model for events generated by user code
> --------------------------------------------------------------------
>
> Key: TEZ-1539
> URL: https://issues.apache.org/jira/browse/TEZ-1539
> Project: Apache Tez
> Issue Type: Improvement
> Reporter: Siddharth Seth
> Assignee: Siddharth Seth
> Attachments: TEZ-1539.1.wip.txt, TEZ-1539.2.txt, TEZ-1539.3.txt,
> TEZ-1539.4.txt
>
>
> Specifically for InputInitalizerEvents and VertexManagerEvents.
> Pasting comment from TEZ-1447
> In a majority of cases, events generated by different attempts of the same
> task will be identical - in which case just making use of the event generated
> by the first successful attempt is adequate. Doing something like this manes
> that users don't worry about retries, indices etc - and can just rely on
> receiving a set of events which are to be processed once the vertex succeeds.
> If different attempts of the same workload generate different events -
> processing is likely to be incorrect, since it's very possible for all data
> to be processed (VERTEX successful), then a failure and retry - which
> generates a different event. The initializer doesn't even run at this point,
> since it's already done it's work and is complete. Handling such scenarios,
> likely involves re-running the entire initializer and re-starting the vertex
> which processed the event from scratch. In situations like this, where data
> generated may be different, the best bet is for speculation to be disabled
> (when it's supported), and max-attempts to be set to 1.
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