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Jian He commented on YARN-3136: ------------------------------- bq. But createReleaseCache schedules a timer task that Ah, yes, you are right. I missed the part that it's on a timer. thanks for pointing out ! bq. the simplest thing to do here is to just document (or require, by changing the type from Map to ConcurrentMap as I originally suggested) that the underlying map must support concurrent access. I agree. > getTransferredContainers can be a bottleneck during AM registration > ------------------------------------------------------------------- > > Key: YARN-3136 > URL: https://issues.apache.org/jira/browse/YARN-3136 > Project: Hadoop YARN > Issue Type: Sub-task > Components: scheduler > Affects Versions: 2.6.0 > Reporter: Jason Lowe > Assignee: Sunil G > Attachments: 0001-YARN-3136.patch, 0002-YARN-3136.patch, > 0003-YARN-3136.patch, 0004-YARN-3136.patch, 0005-YARN-3136.patch > > > While examining RM stack traces on a busy cluster I noticed a pattern of AMs > stuck waiting for the scheduler lock trying to call getTransferredContainers. > The scheduler lock is highly contended, especially on a large cluster with > many nodes heartbeating, and it would be nice if we could find a way to > eliminate the need to grab this lock during this call. We've already done > similar work during AM allocate calls to make sure they don't needlessly grab > the scheduler lock, and it would be good to do so here as well, if possible. -- This message was sent by Atlassian JIRA (v6.3.4#6332)