Brook Zhou created YARN-6870: -------------------------------- Summary: 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
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