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Daniel Templeton commented on YARN-6956: ---------------------------------------- That behavior was intentional to prevent the case where we preempt 8 1GB containers on 8 different nodes to make space for 1 8GB container. > preemption may only consider resource requests for one node > ----------------------------------------------------------- > > Key: YARN-6956 > URL: https://issues.apache.org/jira/browse/YARN-6956 > Project: Hadoop YARN > Issue Type: Bug > Components: fairscheduler > Affects Versions: 2.9.0, 3.0.0-beta1 > Environment: CDH 5.11.0 > Reporter: Steven Rand > > I'm observing the following series of events on a CDH 5.11.0 cluster, which > seem to be possible after YARN-6163: > 1. An application is considered to be starved, so {{FSPreemptionThread}} > calls {{identifyContainersToPreempt}}, and that calls > {{FSAppAttempt#getStarvedResourceRequests}} to get a list of > {{ResourceRequest}} instances that are enough to address the app's starvation. > 2. The first {{ResourceRequest}} that {{getStarvedResourceRequests}} sees is > enough to address the app's starvation, so we break out of the loop over > {{appSchedulingInfo.getAllResourceRequests()}} after only one iteration: > https://github.com/apache/hadoop/blob/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java#L1180. > We return only this one {{ResourceRequest}} back to the > {{identifyContainersToPreempt}} method. > 3. It turns out that this particular {{ResourceRequest}} happens to have a > value for {{getResourceName}} that identifies a specific node in the cluster. > This causes preemption to only consider containers on that node, and not the > rest of the cluster. > [~kasha], does that make sense? I'm happy to submit a patch if I'm > understanding the problem correctly. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: yarn-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: yarn-issues-h...@hadoop.apache.org