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doc/changes/DM-36412.feature.rst

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+If ``pipetask`` is run with multiple processes and if a butler datastore cache is configured, all subprocesses will now share the same cache.
+For large numbers of simultaneous processes it may be necessary to significantly increase the number of datasets in the cache to make the cache usable.
+This can be done by using the ``$DAF_BUTLER_CACHE_EXPIRATION_MODE`` environment variable.
+
+Previously each subprocess would get its own cache and if ``fork`` start method was used these cache directories would not be cleaned up.