https://www.jianshu.com/p/b9245242472b

https://stackoverflow.com/questions/42637631/what-does-virtual-core-in-yarn-vcore-mean

https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.6.5/bk_yarn-resource-management/content/enabling_cgroups.html

https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.6.5/bk_yarn-resource-management/content/using_cgroups.html

http://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/NodeManagerCgroups.html

https://developer.ibm.com/hadoop/2017/06/30/deep-dive-yarn-cgroups/

https://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/FairScheduler.html

​Chapter 11. Using the YARN CLI to View Logs for Running Applications

This chapter describes how to use the YARN CLI (Command Line Interface) to view log files for running applications. You can access container log files using the YARN ResourceManager web UI, but more options are available when you use the yarn logs CLI command.

​View all Log Files for a Running Application

Use the following command format to view all logs for a running application:

yarn logs -applicationId 
      

​View a Specific Log Type for a Running Application

Use the following command format to view all logs of a particular type for a running application:

yarn logs -applicationId 
      
        -log_files 
       
      

For example, to view only the stderr error logs:

yarn logs -applicationId 
      
        -log_files stderr
      

The -logFiles option also supports Java regular expressions, so the following format would return all types of log files:

yarn logs -applicationId 
      
        -log_files .*
      

​View ApplicationMaster Log Files

Use the following command format to view all ApplicationMaster container log files for a running application:

yarn logs -applicationId 
      
        -am ALL
      

Use the following command format to view only the first ApplicationMaster containter log files:

yarn logs -applicationId 
      
        -am 1
      

​List Container IDs

Use the following command format to list all container IDs for a running application:

yarn logs -applicationId 
      
        -show_application_log_info
      

​View Log Files for One Container

Once you have the container IDs, you can use the following command format to list the log files for a particular container:

yarn logs -applicationId 
      
        -containerId 
       
      

​Show Container Log File Information

Use the following command format to list all of the container log file names (types) for a running application:

yarn logs -applicationId 
      
        -show_container_log_info
      

You can then use the -logFiles option to view a particular log type.

​View a Portion of the Log Files for One Container

For large container log files, you can use the following command format to list only a portion of the log files for a particular container:

yarn logs -applicationId 
      
        -containerId 
       
         -size 
        
       
      

To view the first 1000 bytes:

yarn logs -applicationId 
      
        -containerId 
       
         -size 1000
       
      

To view the last 1000 bytes:

yarn logs -applicationId 
      
        -containerId 
       
         -size -1000
       
      

​Download Logs for a Running Application

Use the following command format to download logs to a local folder:

yarn logs -applicationId 
      
        -out 
       
      

The container log files are organized in parent folders labeled with the applicable node ID.

​Display Help for YARN Logs

To display Help for yarn logs, run the following commmand:

yarn logs -help

Commands for testing

These operations are here primarily for testing.

kill-container <name> --id container-id

Kill a YARN container belong to the application. This is useful primarily for testing the resilience to failures.

Container IDs can be determined from the application instance status JSON document.