Details
-
Improvement
-
Status: Resolved
-
Major
-
Resolution: Fixed
-
None
-
None
-
None
Description
Likely solutions to YARN-1680 (properly handling node and rack blacklisting with cluster level node additions and removals) will entail managing an application-level "slice" of the cluster resource available to the application for use in accurately calculating the application headroom and user limit. There is an assumption that events which impact this resource will occur less frequently than the need to calculate headroom, userlimit, etc (which is a valid assumption given that occurs per-allocation heartbeat). Given that, the application should (with assistance from cluster-level code...) detect changes to the composition of the cluster (node addition, removal) and when those have occurred, calculate an application specific cluster resource by comparing cluster nodes to it's own blacklist (both rack and individual node). I think it makes sense to include nodelabel considerations into this calculation as it will be efficient to do both at the same time and the single resource value reflecting both constraints could then be used for efficient frequent headroom and userlimit calculations while remaining highly accurate. The application would need to be made aware of nodelabel changes it is interested in (the application or removal of labels of interest to the application to/from nodes). For this purpose, the application submissions's nodelabel expression would be used to determine the nodelabel impact on the resource used to calculate userlimit and headroom (Cases where the application elected to request resources not using the application level label expression are out of scope for this - but for the common usecase of an application which uses a particular expression throughout, userlimit and headroom would be accurate) This could also provide an overall mechanism for handling application-specific resource constraints which might be added in the future.