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https://issues.apache.org/jira/browse/YARN-7800?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Weiwei Yang reassigned YARN-7800:
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Assignee: Weiwei Yang
> Bind node constraint once a container is proposed to be placed on this node
> ---------------------------------------------------------------------------
>
> Key: YARN-7800
> URL: https://issues.apache.org/jira/browse/YARN-7800
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: RM
> Reporter: Weiwei Yang
> Assignee: Weiwei Yang
> Priority: Major
>
> We found when there is circular dependency between multiple scheduling
> requests, allocation decisions made by placement constraint algorithm might
> be conflicting with related tags. More describing of the issue please refer
> to YARN-7783.
> To solve this issue, a possible solution is to bind *node constraint*. If the
> algorithm wants to place any new container to this node, except for checking
> if it satisfies the placement constraint, it also check if it satisfies the
> node constraint. For example
> 1) "foo", anti-affinity with "foo"
> +Implies node constraint:+ on each node, it cannot have more than 1 foo tags
> 2) "bar", anti-affinity with "foo"
> +Implies node constraint:+ on each node, it cannot have both "bar" and "foo"
> tags
> With such constraint, it works like
> * req2 is placed on any of nodes, e.g n2, +a node constraint[1] is added to
> n2 that constrains this node cannot have both "bar" and "foo" tags+
> * when the algorithm wants to place req1 on n2, it checks if its placement
> constraint is satisfied. It should be as there is no foo container on this
> node yet.
> * Then the algorithm checks if the node constraint is satisfied. It is not
> because it violate node constraint [1].
> This avoids to do additional re-attempt like what was done in YARN-7783.
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