Hello yarn-dev@ We feel that the YARN-6592 dev branch mostly in shape to be merged into trunk. This branch adds support for placing containers in YARN using rich placement constraints. For example, this can be used by applications to co-locate containers on a node or rack (*affinity *constraint), spread containers across nodes or racks (*anti-affinity* constraint), or even specify the maximum number of containers on a node/rack (*cardinality * constraint).
We have integrated this feature into the Distributed-Shell application for feature testing. We have performed end-to-end testing on moderately-sized clusters to verify that constraints work fine. Performance tests have been done via both SLS tests and Capacity Scheduler performance unit tests, and no regression was found. We have opened a JIRA to track Jenkins acceptance of the aggregated patch [2]. Documentation is in the process of being completed [3]. You can also check our design document for more details [4]. Config flags are needed to enable this feature and it should not have any effect on YARN when turned off. Once merged, we plan to work on further improvements, which can be tracked in the umbrella YARN-7812 [5]. Kindly do take a look at the branch and raise issues/concerns that need to be addressed before the merge. Many thanks to Konstantinos, Wangda, Panagiotis, Weiwei, and Sunil for their contributions to this effort, as well as Subru, Chris, Carlo, and Vinod for their inputs and discussions. Cheers -Arun [1] https://issues.apache.org/jira/browse/YARN-6592 [2] https://issues.apache.org/jira/browse/YARN-7792 [3] https://issues.apache.org/jira/browse/YARN-7780 [4] https://issues.apache.org/jira/secure/attachment/12867869/YARN-6592-Rich-Placement-Constraints-Design-V1.pdf [5] https://issues.apache.org/jira/browse/YARN-7812
