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https://issues.apache.org/jira/browse/FLINK-9289?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16473729#comment-16473729
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ASF GitHub Bot commented on FLINK-9289:
---------------------------------------
GitHub user xccui opened a pull request:
https://github.com/apache/flink/pull/6003
[FLINK-9289] Parallelism of generated operators should have max parallelism
of input
## What is the purpose of the change
This PR aims to fix the default parallelism problem for the generated
key-extraction mapper whose input is a union operator without parallelism in
the batch environment.
## Brief change log
- When creating a `Union` operator, automatically set its parallelism to
the maximum one of its inputs.
- Forbid the user to set parallelism for the union operator manually.
- Add some test cases in `UnionOperatorTest.java` and
`UnionTranslationTest.java`.
- Adjust the results for `testUnionWithoutExtended()` and
`testUnionWithExtended()` in `org.apache.flink.table.api.batch.ExplainTest`.
- Remove the parallelism setting code for union in
`PythonPlanBinder.java` and `PageRank.java`.
## Verifying this change
The change can be verified by the added test cases in
`UnionOperatorTest.java` and `UnionTranslationTest.java`.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (no)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (no)
- The serializers: (no)
- The runtime per-record code paths (performance sensitive): (no)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
- The S3 file system connector: (no)
## Documentation
- Does this pull request introduce a new feature? (no)
- If yes, how is the feature documented? (not applicable)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/xccui/flink FLINK-9289-parallelism
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/6003.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #6003
----
commit 35be0811ef0a5e6c572d0a60160fa18c3b6afefa
Author: Xingcan Cui <xingcanc@...>
Date: 2018-05-13T12:20:36Z
[FLINK-9289] Parallelism of generated operators should have max parallism
of input
----
> Parallelism of generated operators should have max parallism of input
> ---------------------------------------------------------------------
>
> Key: FLINK-9289
> URL: https://issues.apache.org/jira/browse/FLINK-9289
> Project: Flink
> Issue Type: Bug
> Components: DataSet API
> Affects Versions: 1.5.0, 1.4.2, 1.6.0
> Reporter: Fabian Hueske
> Assignee: Xingcan Cui
> Priority: Major
>
> The DataSet API aims to chain generated operators such as key extraction
> mappers to their predecessor. This is done by assigning the same parallelism
> as the input operator.
> If a generated operator has more than two inputs, the operator cannot be
> chained anymore and the operator is generated with default parallelism. This
> can lead to a {code}NoResourceAvailableException: Not enough free slots
> available to run the job.{code} as reported by a user on the mailing list:
> https://lists.apache.org/thread.html/60a8bffcce54717b6273bf3de0f43f1940fbb711590f4b90cd666c9a@%3Cuser.flink.apache.org%3E
> I suggest to set the parallelism of a generated operator to the max
> parallelism of all of its inputs to fix this problem.
> Until the problem is fixed, a workaround is to set the default parallelism at
> the {{ExecutionEnvironment}}:
> {code}
> ExecutionEnvironment env = ...
> env.setParallelism(2);
> {code}
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