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https://issues.apache.org/jira/browse/FLINK-7486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16173650#comment-16173650
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ASF GitHub Bot commented on FLINK-7486:
---------------------------------------
Github user EronWright commented on a diff in the pull request:
https://github.com/apache/flink/pull/4628#discussion_r140051191
--- Diff:
flink-mesos/src/main/java/org/apache/flink/mesos/runtime/clusterframework/MesosFlinkResourceManager.java
---
@@ -663,6 +666,7 @@ private void taskTerminated(Protos.TaskID taskID,
Protos.TaskStatus status) {
//
------------------------------------------------------------------------
private LaunchableMesosWorker createLaunchableMesosWorker(Protos.TaskID
taskID) {
+ setCoTaskGetter();
--- End diff --
I believe that this approach is violating an Akka rule by passing a direct
reference to the RM object to the launch coordinator. I understand the
challenge to be that Fenzo's `BalancedHostAttrConstraint` expects a
`coTasksGetter` function
([ref](http://netflix.github.io/Fenzo/fenzo-core/com/netflix/fenzo/plugins/BalancedHostAttrConstraint.html#BalancedHostAttrConstraint-com.netflix.fenzo.functions.Func1-java.lang.String-int-)).
But that function cannot keep a reference to the RM object.
An imperfect solution would be to pass the `taskIds` to the
`LaunchableMesosWorker` constructor; imperfect because the list wouldn't be
dynamic.
In truth we want all tasks to be balanced and so the getter is actually
overkill. If you look at the implementation of `BalancedHostAttrConstraint`
([ref](https://github.com/Netflix/Fenzo/blob/master/fenzo-core/src/main/java/com/netflix/fenzo/plugins/BalancedHostAttrConstraint.java))
it uses the function output to lookup tasks in the `TaskTrackerState`. A
custom constraint could simply use all tasks in `TaskTrackerState` without
need for a `coTasksGetter`.
Once we get this sorted out, some of the code should be moved to a utility
class.
> flink-mesos: Support for adding unique attribute / group_by attribute
> constraints
> ---------------------------------------------------------------------------------
>
> Key: FLINK-7486
> URL: https://issues.apache.org/jira/browse/FLINK-7486
> Project: Flink
> Issue Type: Improvement
> Components: Mesos
> Affects Versions: 1.3.2
> Reporter: Bhumika Bayani
> Assignee: Bhumika Bayani
>
> In our setup, we have multiple mesos-workers. Inspite of this, flink
> application master most of the times ends up spawning all task-managers on
> same mesos-worker.
> We intend to ensure HA of task managers. We would like to make sure each
> task-manager is running on different mesos-worker as well as such
> mesos-worker which does not share the AZ attribute with earlier task manager
> instances.
> Netflix-fenzo supports adding UniqueHostAttribute and BalancedHostAttribute
> contraints. Flink-mesos should also enable us to add these kind of
> constraints.
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