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https://issues.apache.org/jira/browse/FLINK-3255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15106508#comment-15106508
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ASF GitHub Bot commented on FLINK-3255:
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Github user uce commented on the pull request:
https://github.com/apache/flink/pull/1518#issuecomment-172794454
Changes look good.
For the added test, changing the parallelism to 2 results in different
chaining behaviour again. Instead of 2 vertices at parallelism 1, we get 3
vertices at parallelism 2. I didn't look in detail into the chaining conditions
in the streaming job graph generator, but it looks like there is another
parallelism-dependent chaining optimization somewhere. If this is expected,
then it good to merge. +1
> Chaining behavior should not depend on parallelism
> --------------------------------------------------
>
> Key: FLINK-3255
> URL: https://issues.apache.org/jira/browse/FLINK-3255
> Project: Flink
> Issue Type: Bug
> Components: Streaming
> Affects Versions: 1.0.0
> Reporter: Stephan Ewen
> Assignee: Stephan Ewen
> Fix For: 0.10.1
>
>
> Currently, operators are chained more aggressively when the parallelism is
> one. That makes debugging tougher as it changes threading behavior.
> The benefits are also limited: Real installations where that type of
> efficiency would be needed would not run in parallelism 1, or would not use a
> partitioning/broadcast step there (if explicitly required to run parallelism
> 1).
> In the future, when we want to allow parallelism to be adjusted dynamically,
> this will be even more tricky.
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