narendly commented on a change in pull request #1006:
URL: https://github.com/apache/helix/pull/1006#discussion_r426925697
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File path: helix-core/src/main/java/org/apache/helix/task/RuntimeJobDag.java
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@@ -145,9 +145,21 @@ public boolean finishJob(String job) {
String.format("Job: %s has either finished already, never been
scheduled, or been removed from DAG", job));
}
// Add finished job's successors to ready-list
+
+ // If it is a jobQueue, there should be a check to make sure that the a
job has not been added
+ // to the _readyJobList multiple times. This check is necessary because
once the controller
+ // switch happens, the _readyJobList and _inflightJobList will be created
from scratch. In this
+ // case, since there might be many jobs that have been finished before, we
do not want to have a
+ // job several times to the _readyJobList. If _readyJobList has multiple
instances of the same
+ // job, it can compromise the functionality of the parallel jobs.
Review comment:
Have a follow up question. What do you mean the job gets added several
times to the readyJobList?
If there's a controller switch, we'll be creating
readyJobList/inflightJobList from scratch, and add everything from the
beginning (or the first available job from the step-by-step topological sort).
Then as long as the controller doesn't switch, it only gets added once, right?
In other words, for each controller should add a job exactly once. Is that
correct?
Also even though a job might get added to readyJobList multiple times
(exactly once in different controllers), our scheduling logic just skips it I
believe (if jobState is complete/progress we just skip?). Could you help me
understand how this could help? It seems that although this wouldn't hurt to
do...
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