Spacecraft Operations with YARN Logs

Introduction

In a distant galaxy, the Andromeda Space Station serves as a hub for intergalactic exploration and research. As a skilled spacecraft pilot, your mission is to navigate through the vast expanse of space, collecting and analyzing data from various celestial bodies. However, your journey is not without challenges. The spacecraft's on-board computer system, powered by Hadoop, requires you to master the art of managing and monitoring its resources efficiently using Yarn Commands log.

Your objective is to ensure smooth operations during your expeditions by gaining a comprehensive understanding of Yarn Commands log, a powerful tool within the Hadoop ecosystem. By mastering this tool, you'll be able to monitor the resource usage, track job progress, and troubleshoot any issues that may arise, ultimately ensuring the success of your missions.

Skills Graph

Familiarize With Yarn Commands Log

In this step, you'll learn about the fundamental concepts of Yarn Commands log and its role in managing resources within the Hadoop ecosystem.

First, change the user to hadoop and then switch to the home directory of the hadoop user:

su - hadoop

Then, view the list of available Yarn Commands.

yarn --help

The yarn --help command displays a list of available subcommands and their descriptions. Among these subcommands, you'll find several related to logs, such as yarn logs, yarn top, and yarn node.

Here's an example of the output you might see:

Usage: yarn [--help] [COMMAND]
where COMMAND is one of:
  node           Prints information about a specific node
  logs           Fetch and view logs for a specific container
  top            View cluster information
  ...

To understand the purpose and usage of each subcommand, you can use the -help flag along with the subcommand name. For example:

yarn logs -help

This will provide detailed information about the yarn logs subcommand, including its syntax, options, and examples.

Viewing Container Logs

In this step, you'll learn how to retrieve and view logs for a specific container using the yarn logs command.

First, let's submit a sample job to generate some logs:

Navigate to the Hadoop examples directory.

cd /home/hadoop/hadoop/share/hadoop/mapreduce

Run the WordCount example.

yarn jar hadoop-mapreduce-examples-3.3.6.jar wordcount /home/hadoop/input /home/hadoop/output

Once the job is running or completed, you can fetch the logs using the yarn logs command:

Get the application ID from the job output.

appId="application_1234567890123_0001"

View the logs for the specified application.

yarn logs -applicationId $appId

Replace application_1234567890123_0001 with the actual application ID from your job output.

The yarn logs command will display the combined logs from all containers associated with the specified application. You can also view logs for a specific container by using the -containerId option:

containerId="container_1234567890123_0001_01_000001"

yarn logs -applicationId $appId -containerId $containerId

Replace container_1234567890123_0001_01_000001 with the actual container ID you want to inspect.

Monitoring Cluster Resources

The yarn top command provides a real-time view of the cluster's resource utilization, including information about running applications, node managers, and resource allocation.

yarn top

The output will display a summary of the cluster's resource usage, including the total available resources, allocated resources, and pending resources. Additionally, it will list the running applications, their progress, and the resources they are consuming.

Inspecting Node Information

The yarn node command allows you to inspect detailed information about a specific node manager or resource manager within the Hadoop cluster.

List information about all nodes in the cluster.

yarn node -list

Replace iZj6c7ur7j3az0k9shzn2kZ:38115 with the node manager ID.

nodeId="iZj6c7ur7j3az0k9shzn2kZ:38115"

To view information about a node manager:

yarn node -status $nodeId

The output will display information such as the node manager's address, node health status, available resources, and a list of running containers on the node.

Summary

In this lab, you learned how to navigate the vast expanse of Hadoop's resource management through Yarn Commands log. By mastering these commands, you gained the ability to monitor resource usage, track job progress, and troubleshoot issues within the Hadoop ecosystem. This knowledge will be invaluable as you embark on your intergalactic missions, ensuring efficient operations and successful data collection from celestial bodies. The journey to becoming a skilled spacecraft pilot has taken a significant step forward, and you are now better equipped to handle the challenges that lie ahead in the depths of space.