WinkerDu opened a new pull request #29000:
URL: https://github.com/apache/spark/pull/29000
…tion overwrite mode
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### What changes were proposed in this pull request?
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When using dynamic partition overwrite, each task has its working dir under
staging dir like `stagingDir/.spark-staging-{jobId}`, each task commits to
`stagingDir/.spark-staging-{jobId}/{partitionId}/part-{taskId}-{jobId}{ext}`.
When speculation enable, multiple task attempts would be setup for one task,
**they have same task id and they would commit to same file concurrently**. Due
to host done or node preemption, the partly-committed files aren't cleaned up,
a FileAlreadyExistsException would be raised in this situation, resulting in
job failure.
I don't try to change task commit process for dynamic partition overwrite,
like adding attempt id to task working dir for each attempts and committing to
final output dir via a new outputCommitCoordinator, here is reason:
1. `FIleOutputCommitter` already has commit coordinator for each task
attempts, we can leverage it rather than build a new one.
2. To say the least, we implement a coordinator solving task attempts commit
conflict, suppose a severe case, application master failover, tasks with same
attempt id and same task id would commit to same files, the
`FileAlreadyExistsException` risk still exists
In this pr, I leverage FIleOutputCommitter to solve the problem:
1. when initing a write job description, set
`stagingDir/.spark-staging-{jobId}` as the final output dir
2. each task attempt writes output to
`stagingDir/.spark-staging-{jobId}/_temporary/${appAttemptId}/_temporary/${taskAttemptId}/{partitionId}/part-{taskId}-{jobId}{ext}`
3. leverage `FIleOutputCommitter` coordinator, write job firstly commits
output to `stagingDir/.spark-staging-{jobId}/{partitionId}`
4. for dynamic partition overwrite, write job finally move
`stagingDir/.spark-staging-{jobId}/{partitionId}` to `finalPath/{partitionId}`
### Why are the changes needed?
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Without this pr, dynamic partition overwrite would fail
### Does this PR introduce _any_ user-facing change?
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No.
### How was this patch tested?
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added UT.
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