Avoid mutating sampler.pool as a side effect of pickling#572
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EnsembleSampler.__getstate__ assigned self.__dict__ to a local name and then set pool to None on it, which mutated the live object in place. Pickling a sampler (directly, via copy.copy, or via any library that calls __getstate__) permanently discarded its pool and broke subsequent parallel sampling on the original instance. Signed-off-by: Mike German <mike@stepsventures.com>
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EnsembleSampler.__getstate__didd = self.__dict__(a reference, not a copy) and thend["pool"] = None. Any pickle,copy.copy, or checkpoint of the sampler therefore permanently nulled the original object'spool, silently breaking parallel sampling for the rest of the run. The fix copies the dict first:d = self.__dict__.copy().Reproduced with a real
multiprocessing.Pool: the live sampler's pool becameNoneafterpickle.dumps. Addedtest_pickle_does_not_mutate_original_pool, which fails before and passes after. Full suite 129/129.