DAOS-19058 pydaos: torch surface worker errors in parallel_list (#18414) - #18488
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DAOS-19058 pydaos: torch surface worker errors in parallel_list (#18414)#18488enakta wants to merge 2 commits into
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Worker processes spawned by _Dfs.parallel_list may raise exceptions that never reached the calling process. This results in indefinite hang during Dataset and IterableDataset construction with no surfaced error to the user. Replacing manual Process + Queue scheme and its queued/processed counter with a multiprocessing.Pool driven by imap_unordered. Pool re-raises worker exceptions in the parent when their results are consumed, so a worker error now propagates as a raised OSError instead of a deadlock, and the Pool context manager reaps all workers on any exit path. `concurrent.futures.ProcessPoolExecutor` would be even better but its initializer/initargs arguments are unavailable before Python 3.7, and the target runtime includes EL8.8 / Python 3.6. Signed-off-by: Denis Barakhtanov <dbarahtanov@enakta.com>
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Ticket title is 'pytorch parallel_list does not surface worker process errors, causing silent hangs' |
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Test stage Functional on EL 9 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18488/1/execution/node/1085/log |
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Jul 1, 2026
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Targeted for 2.8.1. |
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Worker processes spawned by _Dfs.parallel_list may raise exceptions that never reached the calling process. This results in indefinite hang during Dataset and IterableDataset construction with no surfaced error to the user.
Replacing manual Process + Queue scheme and its queued/processed counter with a multiprocessing.Pool driven by imap_unordered. Pool re-raises worker exceptions in the parent when their results are consumed, so a worker error now propagates as a raised OSError instead of a deadlock, and the Pool context manager reaps all workers on any exit path.
concurrent.futures.ProcessPoolExecutorwould be even better but its initializer/initargs arguments are unavailable before Python 3.7, and the target runtime includes EL8.8 / Python 3.6.Steps for the author:
After all prior steps are complete: