Queue wouldn't empty

[Neil Derraugh <ne...@intellifylearning.com>]

Our cluster arrived in a state where I was unable to empty a couple of
queues.  One queue partially emptied, 224 deleted out of 370, leaving 136
stuck.  I believe this state was created when all three disks on the
cluster filled up -- logs weren't being managed.  After cleaning up the
disks I was still unable to clear the queues, so I restarted the cluster.
After restarting the node and/or cluster -- restarted the cluster where as
I should have just restarted the affected node -- I was able to empty the
queues.

The only item of interest in the logs while the queues were stuck was the
following:

[10.80.53.108] out: 2017-10-10 11:04:22,781 INFO [NiFi Web Server-31515]
o.a.n.controller.StandardFlowFileQueue Initiating drop of FlowFiles from
FlowFileQueue[id=a13c595c-015e-1000-0000-00004be5e64d] on behalf of
nderraugh (request identifier=06d0b7d9-015f-1000-ffff-ffff800b7b85)
[10.80.54.234] out: 2017-10-10 11:04:22,778 INFO [NiFi Web Server-249845]
o.a.n.controller.StandardFlowFileQueue Initiating drop of FlowFiles from
FlowFileQueue[id=a13c595c-015e-1000-0000-00004be5e64d] on behalf of
nderraugh (request identifier=06d0b7d9-015f-1000-ffff-ffff800b7b85)
[10.80.52.161] out: 2017-10-10 11:04:22,788 INFO [NiFi Web Server-186824]
o.a.n.controller.StandardFlowFileQueue Initiating drop of FlowFiles from
FlowFileQueue[id=a13c595c-015e-1000-0000-00004be5e64d] on behalf of
nderraugh (request identifier=06d0b7d9-015f-1000-ffff-ffff800b7b85)

I realize this is probably outside the bounds of acceptable system
administration.  But if a bug is warranted I'm happy to try and provide any
other info that might help.