[jira] [Created] (STORM-2738) The number of ackers doesn't default to the number of actual running workers on RAS cluster

["Ethan Li (JIRA)" <ji...@apache.org>]

Ethan Li created STORM-2738:
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             Summary: The number of ackers doesn't default to the number of actual running workers on RAS cluster
                 Key: STORM-2738
                 URL: https://issues.apache.org/jira/browse/STORM-2738
             Project: Apache Storm
          Issue Type: Bug
            Reporter: Ethan Li
            Assignee: Ethan Li
            Priority: Minor
         Attachments: Screen Shot 2017-09-13 at 11.13.41 AM.png

I am pushing back our internal code change.
*Problem*:
If topology.acker.executors is not set,  the number of ackers will be equal to topology.workers. But on RAS cluster, we don't set topology.workers because the number of workers will be determined by the scheduler. So in this case, the number of ackers will always be 1 (see attached screenshot)

*Analysis*:
The number of ackers has to be computed before scheduling happens, so it knows how to schedule the topology. The number of workers is not set until the topology is scheduled, so it is a bit of a chicken and egg problem.

*Solution*:
We could probably use the total amount of requested memory when the topology is submitted divided by the memory per worker to get an estimate that is better than 1.



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