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Chesnay Schepler commented on FLINK-4098: ----------------------------------------- It appears you stumbled on some (to me) unexpected behavior of the underlying iterators. Essentially, when you call `hasNext()` on an empty iterator after it has returned "false" on a previous call your job will lock up. (regardless of whether it is done in an iteration or not) The check you removed isn't technically necessary and is mostly there for historic reasons. But it's also a nice fail-safe in case the sender implementation changes, so i would prefer keeping it even if it means creating a wrapper that exhibits a more expected behavior. > Iteration support in Python API > ------------------------------- > > Key: FLINK-4098 > URL: https://issues.apache.org/jira/browse/FLINK-4098 > Project: Flink > Issue Type: New Feature > Components: Python API > Affects Versions: 1.0.2 > Reporter: Geoffrey Mon > Priority: Minor > > Bulk and delta iterations are not supported in the Python API. Currently > working on this at https://github.com/GEOFBOT/flink -- This message was sent by Atlassian JIRA (v6.3.4#6332)