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https://issues.apache.org/jira/browse/FLINK-13707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16907001#comment-16907001
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Jark Wu commented on FLINK-13707:
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Hi [~stukid], just want to make sure the logic of default max parallelism. I
find the default max parallelism is computed [in this
way|https://github.com/apache/flink/blob/master/flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyGroupRangeAssignment.java#L127]:
{code:java}
Math.min(
Math.max(
MathUtils.roundUpToPowerOfTwo(operatorParallelism + (operatorParallelism / 2)),
DEFAULT_LOWER_BOUND_MAX_PARALLELISM),
UPPER_BOUND_MAX_PARALLELISM)
{code}
The max parallelism is {{roundUpToPowerOfTwo(1.5 * operatorParallelism)}}, so
we have a safe range to increase the parallelism.
Whatever, I think it makes sense to have a global default max parallelism
configuration.
> Make max parallelism configurable
> ----------------------------------
>
> Key: FLINK-13707
> URL: https://issues.apache.org/jira/browse/FLINK-13707
> Project: Flink
> Issue Type: New Feature
> Components: API / DataStream
> Reporter: xuekang
> Priority: Minor
>
> For now, if a user set parallelism larger than 128, and does not set max
> parallelism explicitly, the system will compute a max parallelism, which is
> 1.5 * parallelism. When the job changes the parallelism and recover from a
> savepoint, there may be some problem when restoring states from the
> savepoint, as the number of key groups changed.
> To avoid this problem, and trying not to modify the code of existing jobs,
> we want to configure the default max parallelism in flink-conf.yaml, but it
> is not configurable now.
> Should we make it configurable? Any comments would be appreciated.
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