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From aljoscha <...@git.apache.org>
Subject [GitHub] flink issue #2110: [FLINK-3974] Fix object reuse with multi-chaining
Date Thu, 23 Jun 2016 09:19:43 GMT
Github user aljoscha commented on the issue:

    https://github.com/apache/flink/pull/2110
  
    Thanks for the thorough review, @tillrohrmann!
    
    Your points are valid, maybe I'll have to change this PR but let me first explain my reasoning.
    
    The shallow copy is performed in the one place that all code paths have to go through
because it is the point right before control is passed to the operator. Putting it in different
place would mean placing it in `BroadcastingOutputCollector`, as you mentioned, as well as
in https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/collector/selector/DirectedOutput.java,
which is used when the user does a split()/select() operation (`DataStream.split()`). The
number of places where we have to put this might evolve in the future.
    
    Also, putting it in `BroadcastingOutputCollector` and `DirectedOutput` would mean that
we always do two copies per record for the common case of having object-copying enabled (which
is the default).
    
    About the ITCase. I also don't like having that in there because we are approaching the
2h mark on Travis but I think in this case it's valid. This test really verifies that the
whole system works correctly when the user uses a certain feature (I would also add a test
for split()/select() now that I thought about it). 


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