[jira] [Commented] (HELIX-601) Allow work flow to schedule dependency jobs in parallel

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HELIX-601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14609556#comment-14609556 ] 

ASF GitHub Bot commented on HELIX-601:
--------------------------------------

Github user kanakb commented on the pull request:

    https://github.com/apache/helix/pull/30#issuecomment-117433383
  
    This should fail fast if you try to set parallelism on workflows that do not have a target resource. Also, what if the target resource has its partitions assigned to other instances? I'm not fully convinced that this is safe except in the case where the task has a target resource and that target resource is assigned to a fixed set of instances.


> Allow work flow to schedule dependency jobs in parallel
> -------------------------------------------------------
>
>                 Key: HELIX-601
>                 URL: https://issues.apache.org/jira/browse/HELIX-601
>             Project: Apache Helix
>          Issue Type: New Feature
>            Reporter: Congrui Ji
>
> Currently, Helix won't schedule dependency jobs in a same work flow. For example, if Job2 depends on Job1, Job2 won't be scheduled until every partition of Job1 is completed.
> However, if some participant is very slow, then all dependency jobs is waiting for that single participant.
> Helix should be able to schedule multiple jobs according to a parameter.
> A.C.
> 1. Introduce parallel count parameter in work flow and job queue.
> 2. Dependency jobs can be scheduled according to the parameter (Now the parameter is always 1, so no parallel)
> 3. If Job2 depends on Job1, Job1 is scheduled before Job2.
> 4. No parallel jobs on the same instance. If a instance is running Job1, it won't run Job2 until Job1 is finished. 



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