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Geoffrey Mon commented on FLINK-4098: ------------------------------------- Sorry, I must have made a typo in the previous comment. With some further investigation, I found that the call to {{NonReusingMutableToRegularIteratorWrapper.hasNext()}} (not getNext) in {{PythonStreamer.streamBufferWithoutGroups}} (at [L257|https://github.com/apache/flink/blob/93c61c097a889c55f412ff31524c749851ca872f/flink-libraries/flink-python/src/main/java/org/apache/flink/python/api/streaming/data/PythonStreamer.java#L257]) hangs indefinitely because {{NonReusingMutableToRegularIteratorWrapper.hasNext()}} tries to get the [{{.next()}} object from its {{source}}|https://github.com/apache/flink/blob/b8299bf92d8e3dbe140dd89602699394019b783d/flink-runtime/src/main/java/org/apache/flink/runtime/util/NonReusingMutableToRegularIteratorWrapper.java#L54], which is a {{CountingMutableObjectIterator}}. The {{CountingMutableObjectIterator}} in turn calls a {{ReaderIterator}} which calls {{MutableRecordReader.getNextRecord()}}. On the first iteration of the while loop in that function, the Reader wants {{.getNextBufferOrEvent()}} from its {{SingleInputGate}} which endlessly polls waiting for data [at L421|https://github.com/apache/flink/blob/c78b3c49e0e82874cbfa71e88bf28b99ed395610/flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/SingleInputGate.java#L421]. Thanks for your advice. > 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)