[train/tune] Remove save_to_object/restore_from_object #38757
Merged
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Why are these changes needed?
This PR removes
Trainable.save_to_object
andTrainable.restore_from_object
.These methods were technically public (as they were part of a public class), but they were only used internally in practice. That's why we believe it's fine to remove them without a full deprecation cycle.
The methods stem from a time when a central storage location was not guaranteed. Then, we needed to be able to ship checkpoints between nodes - e.g. from the head node to the worker nodes where the trial is executed, or between nodes, e.g. when PBT trials exploit another trial.
These assumptions are now superseded by a central storage location. We require users to save checkpoints in a location which all nodes can access. We then only have to ship a thin metadata wrapper around, instead of the full serialized checkpoint data. For large checkpoints, this was always infeasible.
Related issue number
Closes #38674
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.