Enabling override of default queue mappings

By default, placement rules are considered only if a target queue is not specified during a job submission.You can change that behaviour to take placement rules into account whether a target queue is specified at job submission or not.

The yarn.scheduler.capacity.queue-mappings-override.enable property controls when placement rules are considered. In the YARN Queue Manager UI, this property is called Override Queue Mapping. By default, the property is set to false, which means the feature is disabled and placement rules cannot override the target queue that was specified at job submission.

The following table shows how it is specified which queue should be used for a job in different scenarios:

Table 1. Target queue speficiation scenarios
Override Queue Mapping	Target queue is specified at job submission?	Placement rules exist?	End result
Disabled (set to `false)`	Yes	Yes	Job is submitted to the queue that was specified by the submitter.
Disabled (set to `false)`	Yes	No	Job is submitted to the queue that was specified by the submitter.
Disabled (set to `false)`	No	Yes	Placement rules specify the target queue.
Disabled (set to `false)`	No	No	Job is submitted to the default queue of the scheduler (`root.default`).
Enabled (set to `true)`	Yes	Yes	Placement rules specify the target queue.
Enabled (set to `true)`	Yes	No	Job is submitted to the queue that was specified by the submitter.
Enabled (set to `true)`	No	Yes	Placement rules specify the target queue.
Enabled (set to `true)`	No	No	Job is submitted to the default queue of the scheduler (`root.default`).

When placement rules override the target queue defined at job submission, the specified queue can still be taken into account if the specified placement rule policy is used. For more information, see Placement rule policies.

In Cloudera Manager, select YARN Queue Manager UI.
A graphical queue hierarchy is displayed in the Overview tab.
Go to the Scheduler Configuration tab.
Find the Override Queue Mappings property. It is disabled by default.
Check the box to enable this feature.
Click Save.
Provide a description of the change and then click OK.

Placement rules are considered even if a target queue is specified during a job submission.