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
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tvalentyn
approved these changes
Apr 23, 2025
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cc: @claudevdm |
The FlumeRunner will enable this feature flag via its canary mechansim. The option is localized to only serialization of transforms because that is what the FlumeRunner wants to cache. It will not enable best-effort deterministic serialization for other uses of pickling.
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rerunning tests |
Codecov ReportAttention: Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #34698 +/- ##
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+ Coverage 54.61% 54.63% +0.02%
Complexity 1480 1480
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Files 1008 1010 +2
Lines 159767 159960 +193
Branches 1079 1079
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+ Hits 87262 87402 +140
- Misses 70403 70456 +53
Partials 2102 2102
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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