[Train] Add a barrier in RayTrainReportCallback to ensure synchronous reporting. #40875
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Why are these changes needed?
ray.train.report
ensures that all workers enter at the same time, but there are no barriers preventing all workers from exiting at the same time. This could lead to anFileNotFoundError
inRayTrainReportCallback
, where local_rank_0 worker exit earlier, deleted the ckpt folder, while other workers are still uploading it.This PR fixed this bug by adding a barrier call right after
ray.train.report
.Related issue number
Checks
git commit -s
) in this PR.scripts/format.sh
to lint the changes in this PR.method in Tune, I've added it in
doc/source/tune/api/
under thecorresponding
.rst
file.