Weiwei Yang created YARN-7800:
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Summary: 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
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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