- Cassandra Sink use direct memorys.
- Start a standalone cluster(1 machines) for test.
- After the cluster started, check the flink web-ui, and record the task manager's memory info. I mean the direct memory part info.
- Start a job which read from kafka and write to cassandra using the cassandra sink, and you can see that the direct memory count in 'Outside JVM' part go up.
- Stop the job, and the direct memory count is not decreased(using 'jmap -histo:live pid' to make the task manager gc).
- Repeat serveral times, the direct memory count will be more and more.