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Arun Suresh commented on YARN-6870: ----------------------------------- Thanks [~brookz]. will commit this shortly > ResourceUtilization/ContainersMonitorImpl is calculating CPU utilization as a > float, which is imprecise > ------------------------------------------------------------------------------------------------------- > > Key: YARN-6870 > URL: https://issues.apache.org/jira/browse/YARN-6870 > Project: Hadoop YARN > Issue Type: Bug > Components: api, nodemanager > Reporter: Brook Zhou > Assignee: Brook Zhou > Attachments: YARN-6870-v0.patch, YARN-6870-v1.patch, > YARN-6870-v2.patch, YARN-6870-v3.patch > > > We have seen issues on our clusters where the current way of computing CPU > usage is having float-arithmetic inaccuracies (the bug is still there in > trunk) > Simple program to illustrate: > {code:title=Bar.java|borderStyle=solid} > public static void main(String[] args) throws Exception { > float result = 0.0f; > for (int i = 0; i < 7; i++) { > if (i == 6) { > result += (float) 4 / (float)18; > } else { > result += (float) 2 / (float)18; > } > } > for (int i = 0; i < 7; i++) { > if (i == 6) { > result -= (float) 4 / (float)18; > } else { > result -= (float) 2 / (float)18; > } > } > System.out.println(result); > } > {code} > // Printed > 4.4703484E-8 > 2017-04-12 05:43:24,014 INFO > org.apache.hadoop.yarn.server.nodemanager.containermanager.monitor.ContainersMonitorImpl: > Not enough cpu for [container_e3295_1491978508342_0467_01_000030], Current > CPU Allocation: [0.8888891], Requested CPU Allocation: [0.11111111] > There are a few places with this issue: > 1. ResourceUtilization.java - set/getCPU both use float. When > ContainerScheduler calls > ContainersMonitor.increase/decreaseResourceUtilization, this may lead to > issues. > 2. AllocationBasedResourceUtilizationTracker.java - hasResourcesAvailable > uses float as well for CPU computation. -- 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