question Re: Yarn: Application Id - How is it generated ? in Archives of Support Questions (Read Only)

Yarn: Application Id - How is it generated ?

dineshc — Tue, 11 Apr 2017 21:19:16 GMT

I want to understand how the applicationId is generated when a job is submitted to Yarn.

Re: Yarn: Application Id - How is it generated ?

deepesh1 — Wed, 12 Apr 2017 00:03:15 GMT

Application IDs are provided by Resource Manager to the client through the ApplicationSubmissionContext. More information can be found here:

https://hadoop.apache.org/docs/r2.7.2/hadoop-yarn/hadoop-yarn-site/WritingYarnApplications.html

Re: Yarn: Application Id - How is it generated ?

jsensharma — Wed, 12 Apr 2017 00:21:37 GMT

@Dinesh Chitlangia

Following code might give the idea on what you are looking out for:

https://github.com/apache/hadoop/blob/release-2.8.0-RC0/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/records/ApplicationId.java#L53-L58

/**
 * <p><code>ApplicationId</code> represents the <em>globally unique</em> 
 * identifier for an application.</p>
 * 
 * <p>The globally unique nature of the identifier is achieved by using the 
 * <em>cluster timestamp</em> i.e. start-time of the 
 * <code>ResourceManager</code> along with a monotonically increasing counter
 * for the application.</p>
 */

  @Public
  @Unstable
  public static ApplicationId newInstance(long clusterTimestamp, int id) {
    ApplicationId appId = Records.newRecord(ApplicationId.class);
    appId.setClusterTimestamp(clusterTimestamp);
    appId.setId(id);
    appId.build();
    return appId;
  }

According to the API, The ApplicationId represents the globally unique identifier for an application. The globally unique nature of the identifier is achieved by using the "cluster timestamp" i.e. The start-time of the "ResourceManager<"/code>" along with a monotonically increasing counter for the application.

https://github.com/apache/hadoop/blob/release-2.8.0-RC0/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/util/Records.java#L35-L37

Re: Yarn: Application Id - How is it generated ?

dineshc — Wed, 12 Apr 2017 07:54:56 GMT

Thank you Deepesh.

Re: Yarn: Application Id - How is it generated ?

dineshc — Wed, 12 Apr 2017 07:55:20 GMT

Perfect. Thank you.