[jira] [Created] (FLINK-14909) Let tasks in a batch get scheduled in topological order and subtaskIndex ascending pattern

[Shang Yuanchun (Jira)]

Zhu Zhu created FLINK-14909:
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             Summary: Let tasks in a batch get scheduled in topological order and subtaskIndex ascending pattern
                 Key: FLINK-14909
                 URL: https://issues.apache.org/jira/browse/FLINK-14909
             Project: Flink
          Issue Type: Sub-task
          Components: Runtime / Coordination
    Affects Versions: 1.10.0
            Reporter: Zhu Zhu
             Fix For: 1.10.0


I'd propose to let tasks in a batch get scheduled in topological order and subtaskIndex ascending pattern.
There can be 2 benefits:
1. there would be less chance for a task to get launched before its upstream tasks, which reduces {{requestPartitionState}} RPCs to JobMaster.
2. logs could be more readable, e.g.
ordered:
Source: source (1/20) ... switched from CREATED to SCHEDULED.
Source: source (2/20) ... switched from CREATED to SCHEDULED.
...
Source: source (20/20) ... switched from CREATED to SCHEDULED.
Flat Map (1/20) ... switched from CREATED to SCHEDULED.
...
Flat Map (20/20) ... switched from CREATED to SCHEDULED.

disordered:
Source: source (1/20) ... switched from CREATED to SCHEDULED.
Flat Map (11/20) ... switched from CREATED to SCHEDULED.
Source: source (19/20) ... switched from CREATED to SCHEDULED.
Flat Map (2/20) ... switched from CREATED to SCHEDULED.
...

Changes should be made to both {{EagerSchedulingStrategy}} and {{LazyFromSourcesSchedulingStrategy}}.



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