With modern servers it's not uncommon to see environments that has
dozens of logical processors. Glance defaults workers to number of
these logical processors seen by OS and each worker spins up pool
of 1000 threads. Having dozens of these thread pools consuming
resources is total overkill for most of the environments.
This change limits the amount of workers used by default to 8 which
should be plenty for most of the deployments. This limitation does
not affect if more workers is specifically configured in the config
file.
Change-Id: I6fcf2f8a416e34c0c719e1abd73f0525e686be5e
Closes-Bug: #1748916
(cherry picked from commit 6f87c7d567)
ef841b6704