Adding a queue to the capacity scheduler while the RM is running and then running a job in the queue added results in very strange behavior. The cluster Total Memory can either decrease or increase. We had a cluster where total memory decreased to almost 1/6th the capacity. Running on a small test cluster resulted in the capacity going up by simply adding a queue and running wordcount.
Looking at the RM logs, used memory can go negative but other logs show the number positive:
2012-10-21 22:56:44,796 [ResourceManager Event Processor] INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue: assignedContainer queue=root usedCapacity=0.0375 absoluteUsedCapacity=0.0375 used=memory: 7680 cluster=memory: 204800
2012-10-21 22:56:45,831 [ResourceManager Event Processor] INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue: completedContainer queue=root usedCapacity=-0.0225 absoluteUsedCapacity=-0.0225 used=memory: -4608 cluster=memory: 204800