[jira] [Comment Edited] (SPARK-3292) Shuffle Tasks run incessantly even though there's no inputs

2014-10-01 Thread Tathagata Das (JIRA) 

[ 
https://issues.apache.org/jira/browse/SPARK-3292?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=1410#comment-1410
 ] 

Tathagata Das edited comment on SPARK-3292 at 10/1/14 9:18 PM:
---

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() }


was (Author: tdas):
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 , 



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[jira] [Comment Edited] (SPARK-3292) Shuffle Tasks run incessantly even though there's no inputs

2014-09-01 Thread Prashant Sharma (JIRA) 

[ 
https://issues.apache.org/jira/browse/SPARK-3292?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=14117156#comment-14117156
 ] 

Prashant Sharma edited comment on SPARK-3292 at 9/1/14 8:12 AM:


This issue reminds me of a pull request that was trying to not do anything if 
there is nothing to save for streaming jobs. I will try to recollect the PR 
number. But in the meantime, would be great if you could link it. 


was (Author: prashant_):
This issue reminds me of a pull request that was trying to not do anything if 
there is nothing to save. I will try to recollect the PR number. But in the 
meantime, would be great if you could link it. 

 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 , 



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