[jira] [Commented] (SPARK-4094) checkpoint should still be available after rdd actions

["Sean Owen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-4094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14253191#comment-14253191 ] 

Sean Owen commented on SPARK-4094:
----------------------------------

[~liyezhang556520] But this is exactly what the doc says is not permitted. By invoking action C, you necessarily execute the job for RDD B, after which time you can't checkpoint it.

My question, if you're proposing to loosen the restriction, I wonder what problem there was originally to allowing this, and why the change resolves that?

> checkpoint should still be available after rdd actions
> ------------------------------------------------------
>
>                 Key: SPARK-4094
>                 URL: https://issues.apache.org/jira/browse/SPARK-4094
>             Project: Spark
>          Issue Type: Improvement
>          Components: Spark Core
>    Affects Versions: 1.1.0
>            Reporter: Zhang, Liye
>            Assignee: Zhang, Liye
>
> rdd.checkpoint() must be called before any actions on this rdd, if there is any other actions before, checkpoint would never succeed. For the following code as example:
> *rdd = sc.makeRDD(...)*
> *rdd.collect()*
> *rdd.checkpoint()*
> *rdd.count()*
> This rdd would never be checkpointed. For algorithms that have many iterations would have some problem. Such as graph algorithm, there will have many iterations which will cause the RDD lineage very long. So RDD may need checkpoint after a certain iteration number. And if there is also any action within the iteration loop, the checkpoint() operation will never work for the later iterations after the iteration whichs call the action operation.
> But this would not happen for RDD cache. RDD cache would always make successfully before rdd actions no matter whether there is any actions before cache().
> So rdd.checkpoint() should also be with the same behavior with rdd.cache().



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org