Github user fmthoma commented on the issue: https://github.com/apache/flink/pull/6021 @tzulitai I added some docs. As for the `flush()` vs. just waiting: As I see it, the [`RecordMaxBufferedTime`](https://github.com/awslabs/amazon-kinesis-producer/blob/ce77505306c104a6016b0c081df4715d05ac9201/java/amazon-kinesis-producer-sample/default_config.properties#L239) option (default: 100 milliseconds) limits the time a record should be kept in the queue in the absence of pressure. Hence I think that the `flush()` is indeed not necessary, unless a user purposefully sets the `queueLimit` too low *and* the `RecordMaxBufferedTime` too high. Also, I added [another comment](https://github.com/apache/flink/pull/6021#discussion_r190154347) concerning the `sleep` vs `wait`, that github unfortunately displays as »outdated«.
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