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Posted to commits@samza.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2017/11/20 21:40:00 UTC

[jira] [Commented] (SAMZA-1505) Fix CheckpointTool writing only one ssp per task

    [ https://issues.apache.org/jira/browse/SAMZA-1505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16259897#comment-16259897 ] 

ASF GitHub Bot commented on SAMZA-1505:
---------------------------------------

GitHub user xinyuiscool opened a pull request:

    https://github.com/apache/samza/pull/364

    SAMZA-1505: Fix CheckpointTool writing only one ssp per task

    Currently when using CheckpointTool to write checkpoints, it only writes a checkpoint of a single ssp per task. By debugging the code, looks like the flatMap() on the checkpoint of Optional tuple(taskname -> Map(ssp -> offset)) merges the results by key taskname. This patch stores the results explicitly in a list and then groupBy() on it, which fixes the problem.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/xinyuiscool/samza SAMZA-1505

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/samza/pull/364.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #364
    
----
commit 98fb40bdb1f0c5f1c8ab55c231b6fddb0862e739
Author: xiliu <xi...@xiliu-ld1.linkedin.biz>
Date:   2017-11-20T21:36:44Z

    SAMZA-1505: Fix CheckpointTool writing only one ssp per task

----


> Fix CheckpointTool writing only one ssp per task
> ------------------------------------------------
>
>                 Key: SAMZA-1505
>                 URL: https://issues.apache.org/jira/browse/SAMZA-1505
>             Project: Samza
>          Issue Type: Bug
>    Affects Versions: 0.14.0
>            Reporter: Xinyu Liu
>            Assignee: Xinyu Liu
>             Fix For: 0.14.0
>
>
> Currently when using CheckpointTool to write checkpoints, it only writes a checkpoint of a single ssp per task. By debugging the code, looks like the flatMap() on the checkpoint of Optional tuple(taskname -> Map(ssp -> offset)) merges the results by key taskname. So if we have more than one ssps for a task, it will result in only one ssp left after merging. I add a fix by store the results explicitly in a list and then groupBy() on it, which fixed the problem. I still don't understand why scala will merge the key in flatmap.



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