master’s Administrative web UI

Spark Standalone cluster comes with administrative web UI. It is available under http://localhost:8080 by default.

Executor Summary

Executor Summary page displays information about the executors for the application id given as the appId request parameter.

spark standalone webui executor summary
Figure 1. Executor Summary Page

The State column displays the state of an executor as tracked by the master.

When an executor is added to the pool of available executors, it enters LAUNCHING state. It can then enter either RUNNING or FAILED states.

An executor (as ExecutorRunner) sends ExecutorStateChanged message to a worker (that it then sends forward to a master) as a means of announcing an executor’s state change:

  • ExecutorRunner.fetchAndRunExecutor sends EXITED, KILLED or FAILED.

  • ExecutorRunner.killProcess

A Worker sends ExecutorStateChanged messages for the following cases:

  • When LaunchExecutor is received, an executor (as ExecutorRunner) is started and RUNNING state is announced.

  • When LaunchExecutor is received, an executor (as ExecutorRunner) fails to start and FAILED state is announced.

If no application for the appId could be found, Not Found page is displayed.

spark standalone webui appid notfound
Figure 2. Application Not Found Page