Unable to run queries from Hive LLAP queue

[#1]

Two YARN Queues have been setup - default, llap Whichever queue is marked as Hive LLAP Queue (Interactive Query Queue), that queue does not process any queries/job

The following are the steps to reproduce the issye:

1. There are two YARN Queues setup.
In Ambari, default queue is selected for LLAP from the Interactive Query Queue drop down

• (Ambari > Hive > Configs > Interactive Query Queue dropdown).

Any job/query submitted to default queue does not run. However, all queries submitted to LLAP queue runs successfully.

Using the same process listed above, change the Interactive Query Queue to LLAP.

Any query/job submitted to LLAP queue does not run. However, all queries submitted to default queue runs successfully.

Basically, at any time, the LLAP queue does not run any job/query.

Root Cause:

This issue occurs when there is an issue with queue prioritization, where both queues have priority set to 0 which means both are of equal priority. This can be viewed from Ambari > Yarn Queue Manager view.

The Hive LLAP (Low-Latency Analytical Processing) enables us to run Hive queries with low-latency in near real-time. To ensure low-latency, set the priority of the queue used for LLAP to a higher priority, especially if the cluster includes long-running applications.

Solution

To resolve this issue, set the priority of queue LLAP to a higher value higher than the default queue.
After setting the higher priority, ensure to save and refresh the queues for the change to take effect.

For YARN Queue Priorities to be applied, enable preemption. To enable preemption, refer to this documentation.