[jira] [Created] (FLINK-24815) Reduce the cpu cost of calculating stateSize during state allocation

["ming li (Jira)" <ji...@apache.org>]

ming li created FLINK-24815:
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             Summary: Reduce the cpu cost of calculating stateSize during state allocation
                 Key: FLINK-24815
                 URL: https://issues.apache.org/jira/browse/FLINK-24815
             Project: Flink
          Issue Type: Improvement
          Components: Runtime / Checkpointing
            Reporter: ming li


When the task failover, we will reassign the state for each subtask and create a new {{OperatorSubtaskState}} object. At this time, the {{stateSize}} field in the {{OperatorSubtaskState}} will be recalculated. When using incremental {{{}Checkpoint{}}}, this field needs to traverse all shared states and then accumulate the size of the state.

Taking a job with 2000 parallelism and 100 share state for each task as an example, it needs to traverse 2000 * 100 = 20w times. At this time, the cpu of the JM scheduling thread will be full.

I think we can try to provide a construction method with {{stateSize}} for {{OperatorSubtaskState}} or delay the calculation of {{{}stateSize{}}}.



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