How to delete a queue in YARN? - hadoop

Question

I see a queue in the yarn configuration file that I want to delete:
<property>
<name>yarn.scheduler.capacity.root.queues</name>
<value>a,b,c</value>
<description>The queues at the this level (root is the root queue).
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.a.queues</name>
<value>a1,a2</value>
<description>The queues at the this level (root is the root queue).
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.b.queues</name>
<value>b1,b2,b3</value>
<description>The queues at the this level (root is the root queue).
</description>
</property>
Say I want to remove queue c. I remove c from the list under the line <name>yarn.scheduler.capacity.root.queues</name> so that line looks like this:
<value>a,b,c</value>
Then I go to the command line and run yarn rmadmin -refreshQueues.
But I get the following error message:
Caused by java.io.IOException: c cannot be found during refresh!`
I'm trying to delete the queue c. How do I delete it?
I noticed here it says that
Note: Queues cannot be deleted, only addition of new queues is
supported - the updated queue configuration should be a valid one i.e.
queue-capacity at each level should be equal to 100%.
...so, how do I delete a queue if I don't need it anymore?
thanks.

Answer 1

From that page:
Administrators can add additional queues at runtime, but queues cannot be deleted at runtime.
It sounds like you cannot delete at runtime, BUT you can stop/kill the YARN, update the config file (and remove c) and run YARN with the new configuration. So if you can afford to stop/start the YARN then here is the process:
Note: Before killing the YARN Read here on the effects on the system depending on your YARN version.
Here goes the process:
Stop the MapReduce JobHistory service, ResourceManager service, and NodeManager on all nodes where they are running, as follows:
sudo service hadoop-mapreduce-historyserver stop
sudo service hadoop-yarn-resourcemanager stop
sudo service hadoop-yarn-nodemanager stop
Then Edit the config file and remove c
Start the MapReduce JobHistory server, ResourceManager, and NodeManager on all nodes where they were previously running, as follows:
sudo service hadoop-mapreduce-historyserver start
sudo service hadoop-yarn-resourcemanager start
sudo service hadoop-yarn-nodemanager start
Commands are from here

Answer 2

You have to stop Yarn if you want to delete a queue. Only add, update and stop is supported while Yarn is running.