Hong Zhiguo created YARN-2768: --------------------------------- Summary: optimize FSAppAttempt.updateDemand by avoid clone of Resource which takes 85% of computing time of update thread Key: YARN-2768 URL: https://issues.apache.org/jira/browse/YARN-2768 Project: Hadoop YARN Issue Type: Improvement Components: fairscheduler Reporter: Hong Zhiguo Assignee: Hong Zhiguo Priority: Minor
See the attached picture of profiling result. The clone of Resource object within Resources.multiply() takes up **85%** (19.2 / 22.6) CPU time of the function FairScheduler.update(). The code of FSAppAttempt.updateDemand: {code} public void updateDemand() { demand = Resources.createResource(0); // Demand is current consumption plus outstanding requests Resources.addTo(demand, app.getCurrentConsumption()); // Add up outstanding resource requests synchronized (app) { for (Priority p : app.getPriorities()) { for (ResourceRequest r : app.getResourceRequests(p).values()) { Resource total = Resources.**multiply**(r.getCapability(), r.getNumContainers()); Resources.addTo(demand, total); } } } } {code} The code of Resources.multiply: {code} public static Resource multiply(Resource lhs, double by) { return multiplyTo(**clone**(lhs), by); } {code} The clone could be skipped by directly update the value of this.demand. -- This message was sent by Atlassian JIRA (v6.3.4#6332)