viirya opened a new pull request #32136:
URL: https://github.com/apache/spark/pull/32136
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### What changes were proposed in this pull request?
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This patch proposes to add a plugin API for providing scheduling suggestion
to Spark task scheduler.
### Why are the changes needed?
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Spark scheduler schedules tasks to executors in an arbitrary (maybe not
accurate description, but I cannot find good term here) way. The schedule
schedules the tasks by itself. Although there is locality configuration, the
configuration is used for data locality purposes. Generally we cannot suggest
the scheduler where a task should be scheduled to. Normally it is not a problem
because the general task is executor-agnostic.
But for special tasks, for example stateful tasks in Structured Streaming,
state store is maintained at the executor side. Changing task location means
reloading checkpoint data from the last batch. It has disadvantages from the
performance perspective and also casts some limitations when we want to
implement somes features in Structured Streaming.
### Does this PR introduce _any_ user-facing change?
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No. This API should be developer-only and currently for Spark internal only
too.
### How was this patch tested?
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Unit test. Will add more tests.
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