[jira] [Created] (FLINK-1683) Scheduling preferences for non-unary tasks are not correctly computed

[Shang Yuanchun (Jira)]

Fabian Hueske created FLINK-1683:
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             Summary: Scheduling preferences for non-unary tasks are not correctly computed
                 Key: FLINK-1683
                 URL: https://issues.apache.org/jira/browse/FLINK-1683
             Project: Flink
          Issue Type: Bug
          Components: JobManager
    Affects Versions: 0.8.1, 0.9
            Reporter: Fabian Hueske
            Assignee: Fabian Hueske
             Fix For: 0.9, 0.8.2


When computing scheduling preferences for an execution task, the JobManager looks at the assigned instances of all its input execution tasks and returns a preference only if not more than 8 instances have been found (if the input of a tasks is distributed across more than 8 tasks, local scheduling won't help a lot in any case).

However, the JobManager treats all input execution tasks the same and does not distinguish between different logical input. The effect is that a join tasks with one broadcasted and one locally forwarded task is not locally assigned towards its locally forwarded input.

This can have a significant impact on the performance of tasks that have more than one input and which rely on local forwarding and co-located task scheduling.



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