Ngone51 opened a new pull request #29395:
URL: https://github.com/apache/spark/pull/29395
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### What changes were proposed in this pull request?
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1. Make `CoarseGrainedSchedulerBackend.maxNumConcurrentTasks()` considers
all kinds of resources when calculating the max concurrent tasks
2. Refactor `calculateAvailableSlots()` to make it be able to be used for
both `CoarseGrainedSchedulerBackend` and `TaskSchedulerImpl`
### Why are the changes needed?
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Currently, `CoarseGrainedSchedulerBackend.maxNumConcurrentTasks()` only
considers the CPU for the max concurrent tasks. This can cause the application
to hang when a barrier stage requires extra custom resources but the cluster
doesn't have enough corresponding resources. Because, without the checking for
other custom resources in `maxNumConcurrentTasks`, the barrier stage can be
submitted to the `TaskSchedulerImpl`. But the `TaskSchedulerImpl` won't launch
tasks for the barrier stage due to the insufficient task slots calculated by
`TaskSchedulerImpl.calculateAvailableSlots` (which does check all kinds of
resources).
If the barrier stage doesn't launch all the tasks in one true, the
application will fail and suggest user to disable delay scheduling. However,
this actually a misleading suggestion since the real root cause is not enough
resources.
### Does this PR introduce _any_ user-facing change?
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Yes. In case of a barrier stage requires more custom resources than the
cluster has, previously, the application will fail with misleading suggestion
of disabling delay scheduling. After this PR, the application will fail with
the error message saying not enough resources.
### How was this patch tested?
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Added a unit test.
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