[train] Raise ValueError when checkpoint_upload_fn does not return a checkpoint#58863
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justinvyu merged 3 commits intoray-project:masterfrom Nov 24, 2025
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Signed-off-by: Timothy Seah <tseah@anyscale.com>
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This pull request introduces a valuable validation check to ensure that a user-provided checkpoint_upload_fn returns a checkpoint object. By raising a ValueError when the function returns a falsy value, it helps users fail fast and avoid subtle bugs like stalled training runs. The implementation is straightforward and effective. The accompanying unit test is well-written and correctly verifies the new behavior in a distributed setting. Overall, this is a great improvement for user experience and robustness.
justinvyu
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Nov 21, 2025
python/ray/train/v2/tests/test_async_checkpointing_validation.py
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Signed-off-by: Timothy Seah <tseah@anyscale.com>
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python/ray/train/v2/tests/test_async_checkpointing_validation.py
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Signed-off-by: Timothy Seah <tseah@anyscale.com>
ykdojo
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…checkpoint (ray-project#58863) Fail fast if the users forgets to return a checkpoint in their `checkpoint_upload_fn`. This also causes unexpected issues like `get_all_reported_checkpoints` stalling indefinitely because the counter is misaligned, which I can also fix in a separate PR. --------- Signed-off-by: Timothy Seah <tseah@anyscale.com> Signed-off-by: YK <1811651+ykdojo@users.noreply.github.com>
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…checkpoint (ray-project#58863) Fail fast if the users forgets to return a checkpoint in their `checkpoint_upload_fn`. This also causes unexpected issues like `get_all_reported_checkpoints` stalling indefinitely because the counter is misaligned, which I can also fix in a separate PR. --------- Signed-off-by: Timothy Seah <tseah@anyscale.com>
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Summary
Fail fast if the users forgets to return a checkpoint in their
checkpoint_upload_fn. This also causes unexpected issues likeget_all_reported_checkpointsstalling indefinitely because the counter is misaligned, which I can also fix in a separate PR.Testing
Unit tests