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https://issues.apache.org/jira/browse/FLINK-7153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16205895#comment-16205895
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Till Rohrmann commented on FLINK-7153:
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Looking at the code of the {{Scheduler#scheduleTask}}, we execute the task
scheduling logic under a global lock. This means that partially ordering the
task schedulings by introducing input dependencies should not hurt either,
because multiple schedulings will be executed in serial order anyway, if I'm
not mistaken.
> Eager Scheduling can't allocate source for ExecutionGraph correctly
> -------------------------------------------------------------------
>
> Key: FLINK-7153
> URL: https://issues.apache.org/jira/browse/FLINK-7153
> Project: Flink
> Issue Type: Bug
> Components: JobManager
> Affects Versions: 1.3.1
> Reporter: Sihua Zhou
> Assignee: Stephan Ewen
> Priority: Blocker
> Fix For: 1.4.0, 1.3.3
>
>
> The ExecutionGraph.scheduleEager() function allocate for ExecutionJobVertex
> one by one via calling ExecutionJobVertex.allocateResourcesForAll(), here is
> two problem about it:
> 1. The ExecutionVertex.getPreferredLocationsBasedOnInputs will always return
> empty, cause `sourceSlot` always be null until `ExectionVertex` has been
> deployed via 'Execution.deployToSlot()'. So allocate resource base on
> prefered location can't work correctly, we need to set the slot info for
> `Execution` as soon as Execution.allocateSlotForExecution() called
> successfully?
> 2. Current allocate strategy can't allocate the slot optimize. Here is the
> test case:
> {code}
> JobVertex v1 = new JobVertex("v1", jid1);
> JobVertex v2 = new JobVertex("v2", jid2);
> SlotSharingGroup group = new SlotSharingGroup();
> v1.setSlotSharingGroup(group);
> v2.setSlotSharingGroup(group);
> v1.setParallelism(2);
> v2.setParallelism(4);
> v1.setInvokableClass(BatchTask.class);
> v2.setInvokableClass(BatchTask.class);
> v2.connectNewDataSetAsInput(v1, DistributionPattern.POINTWISE,
> ResultPartitionType.PIPELINED_BOUNDED);
> {code}
> Currently, after allocate for v1,v2, we got a local partition and three
> remote partition. But actually, it should be 2 local partition and 2 remote
> partition.
> The causes of the above problems is becuase that the current allocate
> strategy is allocate the resource for execution one by one(if the execution
> can allocate from SlotGroup than get it, Otherwise ask for a new one for it).
> If we change the allocate strategy to two step will solve this problem, below
> is the Pseudo code:
> {code}
> for (ExecutionJobVertex ejv: getVerticesTopologically) {
> //step 1: try to allocate from SlothGroup base on inputs one by one (which
> only allocate resource base on location).
> //step 2: allocate for the remain execution.
> }
> {code}
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