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https://issues.apache.org/jira/browse/FLINK-2897?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15011491#comment-15011491
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ASF GitHub Bot commented on FLINK-2897:
---------------------------------------

Github user tillrohrmann commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1292#discussion_r45231684
  
    --- Diff: 
flink-runtime/src/main/java/org/apache/flink/runtime/operators/shipping/OutputEmitter.java
 ---
    @@ -143,16 +148,24 @@ public OutputEmitter(ShipStrategyType strategy, 
TypeComparator<T> comparator, Pa
        
        // 
--------------------------------------------------------------------------------------------
     
    +   private int[] forward() {
    +           return this.channels;
    +   }
    +
        private int[] robin(int numberOfChannels) {
    -           if (this.channels == null || this.channels.length != 1) {
    -                   this.channels = new int[1];
    +           int nextChannel = this.nextChannelToSendTo;
    +
    +           if (nextChannel >= numberOfChannels) {
    +                   if (nextChannel == numberOfChannels) {
    +                           nextChannel = 0;
    --- End diff --
    
    Shouldn't this case be also covered by `nextChannel %= numberOfChannels`?


> Use distinct initial indices for OutputEmitter round-robin
> ----------------------------------------------------------
>
>                 Key: FLINK-2897
>                 URL: https://issues.apache.org/jira/browse/FLINK-2897
>             Project: Flink
>          Issue Type: Improvement
>          Components: Distributed Runtime
>    Affects Versions: 0.10.0
>            Reporter: Greg Hogan
>            Assignee: Greg Hogan
>
> Currently, when performing a round-robin partitioning each task will 
> sequentially partition starting with partition "1". This is fine in the usual 
> case where the number of partitioned objects greatly exceeds the number of 
> channels. However, in the case where the number of objects is relatively few 
> (each, perhaps, requiring a large computation or access to an external 
> system) it would be much better to begin partitioning at distinct indices 
> (the task index).



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