Github user zhijiangW commented on the issue:
https://github.com/apache/flink/pull/4559
@NicoK @pnowojski , for backlog thread-safe issue, the current
implementation is not thread-safe and we should restore my previous
implementation that calls `decreaseStatistics` inside the method of
`getNextBuffer` to make it inside the `synchronized` region. What do you think?---
