[YARN-10497] Fix an issue in CapacityScheduler which fails to delete queues

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.0
• Fix Version/s: 3.4.0
• Component/s: capacity scheduler
• Labels: capacity-scheduler capacityscheduler
• Target Version/s: 3.4.0
• Hadoop Flags: Reviewed
• Assignee: Wangda Tan
• Reporter: Wangda Tan
• Created: 20/Nov/20 23:31
• Updated: 11/Feb/24 08:46
• Resolved: 17/Mar/21 12:39

Description

We saw an exception when using queue mutation APIs:

2020-11-13 16:47:46,327 WARN org.apache.hadoop.yarn.server.resourcemanager.webapp.RMWebServices: CapacityScheduler configuration validation failed:java.io.IOException: Queue root.am2cmQueueSecond not found

Which comes from this code:

        List<String> siblingQueues = getSiblingQueues(queueToRemove,
            proposedConf);
        if (!siblingQueues.contains(queueName)) {
          throw new IOException("Queue " + queueToRemove + " not found");
        } 

(Inside MutableCSConfigurationProvider)

If you look at the method:

 
  private List<String> getSiblingQueues(String queuePath, Configuration conf) {
    String parentQueue = queuePath.substring(0, queuePath.lastIndexOf('.'));
    String childQueuesKey = CapacitySchedulerConfiguration.PREFIX +
        parentQueue + CapacitySchedulerConfiguration.DOT +
        CapacitySchedulerConfiguration.QUEUES;
    return new ArrayList<>(conf.getStringCollection(childQueuesKey));
  }

And here's capacity-scheduler.xml I got

<property><name>yarn.scheduler.capacity.root.queues</name><value>default, q1, q2</value></property>

You can notice there're spaces between default, q1, a2

So conf.getStringCollection returns:

default
<space>q1
...

Which causes match issue when we try to delete the queue.