upcall: prevent busy loop in reaper thread

http://review.gluster.org/10342 introduced a cleanup thread for expired
client entries. When enabling the 'features.cache-invalidation' volume
option, the brick process starts to run in a busy-loop. Obviously this
is not intentional, and a process occupying 100% of the cycles on a CPU
or core is not wanted.

Cherry picked from commit a367d4c6965e1f0da36f17ab6c5fdbd37925ebdd)\:
> Change-Id: I453c612d72001f4d8bbecdd5ac07aaed75b43914
> BUG: 1200267
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on: http://review.gluster.org/11198
> Reviewed-by: soumya k <skoduri@redhat.com>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
> Tested-by: Gluster Build System <jenkins@build.gluster.com>

Change-Id: I453c612d72001f4d8bbecdd5ac07aaed75b43914
BUG: 1231516
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/11211
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: soumya k <skoduri@redhat.com>

0 files changed, 0 insertions, 0 deletions