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Posted to issues@tez.apache.org by "Ahmed Hussein (JIRA)" <ji...@apache.org> on 2019/05/28 20:57:00 UTC

[jira] [Updated] (TEZ-4067) Tez Speculation decision is calculated on each update by the dispatcher

     [ https://issues.apache.org/jira/browse/TEZ-4067?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ahmed Hussein updated TEZ-4067:
-------------------------------
    Attachment: TEZ-4067.001.patch

> Tez Speculation decision is calculated on each update by the dispatcher
> -----------------------------------------------------------------------
>
>                 Key: TEZ-4067
>                 URL: https://issues.apache.org/jira/browse/TEZ-4067
>             Project: Apache Tez
>          Issue Type: Improvement
>            Reporter: Ahmed Hussein
>            Assignee: Ahmed Hussein
>            Priority: Minor
>         Attachments: TEZ-4067.001.patch
>
>
> LegacySpeculator is an object field in VertexImpl. Therefore, all events are handled synchronously by the caller (dispatcher). This implies the following:
>  # the dispatcher spends long time executing updateStatus as it needs to check the runtime estimation of the tezAttempts within the vertex.
>  # the speculator is per stage: lunching a speculation may not the optimum decision. Ideally, based on resources, speculated tasks should be the ones with slowest progress.
>  # the time between speculation is skewed because there is a big delay for the dispatcher to complete a full cycle. Also, speculation will be more aggressive compared to MR because MR waits for "soonest.retry.after.speculate" whenever a task is speculated. On the other hand, Tez speculates more tasks as it processes stages in parallel.
>  



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