Add option to pickler dumps() for best-effort determinism #34698
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The motivation for this change is Flume caches pickled code and non-determinism breaks the caching. While making pickling fully-determinism is infeasible, increasing the determinism is still useful due to the increase in cache hits. Sets are a common source of non-determinism. This change sorts set elements to provide deterministic serialization. Because not all types provide a comparison operator, the sorting routine implements generic element comparison logic. See: apache#34410
tvalentyn
reviewed
Apr 21, 2025
| """For internal use only; no backwards-compatibility guarantees.""" | ||
| with _pickle_lock: | ||
| if enable_best_effort_determinism: | ||
| dill.dill.pickle(set, save_set) |
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does this create a side-effect (for future invocations where we have enable_best_effort_determinism=False again) ?
|
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The motivation for this change is Flume caches pickled code and non-determinism breaks the caching. While making pickling fully-determinism is infeasible, increasing the determinism is still useful due to the increase in cache hits. Sets are a common source of non-determinism. This change sorts set elements to provide deterministic serialization. Because not all types provide a comparison operator, the sorting routine implements generic element comparison logic.
See: #34410