[
https://issues.apache.org/jira/browse/SPARK-4094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14255367#comment-14255367
]
Zhang, Liye commented on SPARK-4094:
------------------------------------
HI [~sowen], I'm also wondering why the original way is restricted. But for the
real-world case, especially for graph algorithms that has many iterations, this
restricted too much.
Hi [~matei], the spark code originally has such restriction. Can you tell if
there are other considerations excluding the complexity involved from
traversing the whole lineage? And if there are problems allowing checkpoint
after rdd actions?
> 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 which calls 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-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
