[jira] [Created] (FLINK-3885) Revisit parallelism logic

["Till Rohrmann (JIRA)" <ji...@apache.org>]

Till Rohrmann created FLINK-3885:
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             Summary: Revisit parallelism logic
                 Key: FLINK-3885
                 URL: https://issues.apache.org/jira/browse/FLINK-3885
             Project: Flink
          Issue Type: Bug
          Components: Streaming
    Affects Versions: 1.1.0
            Reporter: Till Rohrmann


Flink has multiple ways to specify the parallelism of programs. One can set it directly at the operator or job-wide via the {{ExecutionConfig}}. Then it is also possible to define a default parallelism in the {{flink-conf.yaml}}. This default parallelism is only respected on the client side.

For batch jobs, the default parallelism is consistently set in the {{Optimizer}}. However, for streaming jobs the default parallelism is only set iff the {{StreamExecutionEnvironment}} has been created via {{StreamExecutionEnvironment.getExecutionEnvironment()}}. If one creates a {{RemoteStreamEnvironment}}, then the default parallelism won't be respected. Instead the parallelism is {{-1}}. Also the {{JobManager}} does not respect the default parallelism. But whenever it sees a parallelism of {{-1}} it sets it to {{1}}. This behaviour is not consistent with the batch behaviour and the behaviour described in the documentation of {{parallelism.default}}.

On top of that we also have the {{PARALLELISM_AUTO_MAX}} value for the parallelism. This value tells the system to use all available slots. However, this feature is nowhere documented in our docs.

I would propose to get rid of {{PARALLELISM_AUTO_MAX}} and to make the default parallelism behaviour in the batch and streaming API consistent.



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