[GitHub] TisonKun commented on issue #6680: [FLINK-10319] [runtime] Too many requestPartitionState would crash JM

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TisonKun commented on issue #6680: [FLINK-10319] [runtime] Too many requestPartitionState would crash JM
URL: https://github.com/apache/flink/pull/6680#issuecomment-427716261
 
 
   @tillrohrmann it is better to say that `JobMaster` will be overwhelmed by too many rpc request.
   
   This issue is filed during a benchmark of the job scheduling performance with a 2000x2000 ALL-to-ALL streaming(EAGER) job. The input data is empty so that the tasks finishes soon after started.
   
   In this case JM shows slow RPC responses and TM/RM heartbeats to JM will finally timeout. Digging out the reason, there are ~2,000,000 `requestPartitionState` messages triggered by `triggerPartitionProducerStateCheck` in a short time, which overwhelms JM RPC main thread. This is due to downstream tasks can be started earlier than upstream tasks in EAGER scheduling.
   
   For you second question, the task can just keep waiting for a while and retrying if the partition does not exist. There are two cases when the partition does not exist: 1. the partition is not started yet 2. the partition is failed. In case 1, retry works. In case 2, a task failover will soon happen and cancel the downstream tasks as well.

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