Document registry 'workers' option

Currently the 'workers' option -- to increase the number of
service processes -- is only documented for the API.

This change adds the equivalent documentation for the registry.

DocImpact

Change-Id: I0cee0d284eef9ce5dcb26720499f2c4d31eaca0f
Closes-Bug: #1334711

doc/source/configuring.rst

@@ -161,12 +161,11 @@ Optional. Default: ``600``
 
 * ``workers=PROCESSES``
 
-Number of Glance API worker processes to start. Each worker
-process will listen on the same port. Increasing this
-value may increase performance (especially if using SSL
-with compression enabled). Typically it is recommended
-to have one worker process per CPU. The value `0` will
-prevent any new processes from being created.
+Number of Glance API or Registry worker processes to start. Each worker
+process will listen on the same port. Increasing this value may increase
+performance (especially if using SSL with compression enabled). Typically
+it is recommended to have one worker process per CPU. The value `0`
+will prevent any new processes from being created.
 
 Optional. Default: ``1``
 

etc/glance-registry.conf

@@ -29,6 +29,13 @@ backlog = 4096
 # package.
 #data_api = glance.db.sqlalchemy.api
 
+# Number of Glance Registry worker processes to start.
+# On machines with more than one CPU increasing this value
+# may improve performance (especially if using SSL with
+# compression turned on). It is typically recommended to set
+# this value to the number of CPUs present on your machine.
+workers = 1
+
 # Enable Registry API versions individually or simultaneously
 #enable_v1_registry = True
 #enable_v2_registry = True

glance/common/wsgi.py

@@ -76,7 +76,7 @@
 eventlet_opts = [
     cfg.IntOpt('workers', default=1,
                help=_('The number of child process workers that will be '
-                      'created to service API requests.')),
+                      'created to service requests.')),
     cfg.StrOpt('eventlet_hub', default='poll',
                help=_('Name of eventlet hub to use. Traditionally, we have '
                       'only supported \'poll\', however \'selects\' may be '