Troubleshoot Apache Hadoop YARN by using Azure HDInsight
Learn about the top issues and their resolutions when working with Apache Hadoop YARN payloads in Apache Ambari.
How do I create a new YARN queue on a cluster?
Resolution steps
Use the following steps in Ambari to create a new YARN queue, and then balance the capacity allocation among all the queues.
In this example, two existing queues (default and thriftsvr) both are changed from 50% capacity to 25% capacity, which gives the new queue (spark) 50% capacity.
Queue | Capacity | Maximum capacity |
---|---|---|
default | 25% | 50% |
thrftsvr | 25% | 50% |
spark | 50% | 50% |
Select the Ambari Views icon, and then select the grid pattern. Next, select YARN Queue Manager.
Select the default queue.
For the default queue, change the capacity from 50% to 25%. For the thriftsvr queue, change the capacity to 25%.
To create a new queue, select Add Queue.
Name the new queue.
Leave the capacity values at 50%, and then select the Actions button.
Select Save and Refresh Queues.
These changes are visible immediately on the YARN Scheduler UI.
Further reading
How do I download YARN logs from a cluster?
Resolution steps
Connect to the HDInsight cluster by using a Secure Shell (SSH) client. For more information, see Further reading.
To list all the application IDs of the YARN applications that are currently running, run the following command:
yarn top
The IDs are listed in the APPLICATIONID column. You can download logs from the APPLICATIONID column.
YARN top - 18:00:07, up 19d, 0:14, 0 active users, queue(s): root NodeManager(s): 4 total, 4 active, 0 unhealthy, 0 decommissioned, 0 lost, 0 rebooted Queue(s) Applications: 2 running, 10 submitted, 0 pending, 8 completed, 0 killed, 0 failed Queue(s) Mem(GB): 97 available, 3 allocated, 0 pending, 0 reserved Queue(s) VCores: 58 available, 2 allocated, 0 pending, 0 reserved Queue(s) Containers: 2 allocated, 0 pending, 0 reserved APPLICATIONID USER TYPE QUEUE #CONT #RCONT VCORES RVCORES MEM RMEM VCORESECS MEMSECS %PROGR TIME NAME application_1490377567345_0007 hive spark thriftsvr 1 0 1 0 1G 0G 1628407 2442611 10.00 18:20:20 Thrift JDBC/ODBC Server application_1490377567345_0006 hive spark thriftsvr 1 0 1 0 1G 0G 1628430 2442645 10.00 18:20:20 Thrift JDBC/ODBC Server
To download YARN container logs for all application masters, use the following command:
yarn logs -applicationIdn logs -applicationId <application_id> -am ALL > amlogs.txt
This command creates a log file named amlogs.txt.
To download YARN container logs for only the latest application master, use the following command:
yarn logs -applicationIdn logs -applicationId <application_id> -am -1 > latestamlogs.txt
This command creates a log file named latestamlogs.txt.
To download YARN container logs for the first two application masters, use the following command:
yarn logs -applicationIdn logs -applicationId <application_id> -am 1,2 > first2amlogs.txt
This command creates a log file named first2amlogs.txt.
To download all YARN container logs, use the following command:
yarn logs -applicationIdn logs -applicationId <application_id> > logs.txt
This command creates a log file named logs.txt.
To download the YARN container log for a specific container, use the following command:
yarn logs -applicationIdn logs -applicationId <application_id> -containerId <container_id> > containerlogs.txt
This command creates a log file named containerlogs.txt.
Additional reading
Next steps
If you didn't see your problem or are unable to solve your issue, visit one of the following channels for more support:
- If you need more help, you can submit a support request from the Azure portal. Select Support from the menu bar or open the Help + support hub.