spark-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Tathagata Das (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SPARK-3292) Shuffle Tasks run incessantly even though there's no inputs
Date Wed, 01 Oct 2014 21:18:35 GMT

    [ https://issues.apache.org/jira/browse/SPARK-3292?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14155550#comment-14155550
] 

Tathagata Das commented on SPARK-3292:
--------------------------------------

I mentioned this in the PR but I am adding it here as well.  Not returning an RDD can mess
up a lot of the logic and semantics. For example if there is a transform() followed by updateStateByKey(),
the result will be unpredictable. updateStateByKey expects the previous batch to have a state
RDD. If it does not find any state RDD it will assume that this the start of the streamign
computation and effectively initialize again, forgetting the previous states from 2 batches
ago. So this change is incorrect.

Regarding the original problem of creating too many empty files, you can filter that out by
doing explicitly saving yourself.

    dstream.foreachRDD { case (rdd, time) => 
        if (rdd.take(1).size == 1) {
           rdd.saveAsHadoopFile(....)
       }
    }

> Shuffle Tasks run incessantly even though there's no inputs
> -----------------------------------------------------------
>
>                 Key: SPARK-3292
>                 URL: https://issues.apache.org/jira/browse/SPARK-3292
>             Project: Spark
>          Issue Type: Improvement
>          Components: Streaming
>    Affects Versions: 1.0.2
>            Reporter: guowei
>
> such as repartition groupby join and cogroup
> for example. 
> if i want the shuffle outputs save as hadoop file ,even though  there is no inputs ,
many emtpy file generate too.
> it's too expensive , 



--
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


Mime
View raw message