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

["Xinyu Liu (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SAMZA-1505?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Xinyu Liu resolved SAMZA-1505.
------------------------------
    Resolution: Fixed

> 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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