Change worker defaults to ::os_workers

This patch changes the default worker count from ::processorcount to the
new ::os_workers fact. ::os_workers is based on the number of processors
(currently cpu/4) but is capped at a maximum of 8 worker processors.
This is a much more reasonable default in general and prevents excessive
resource consumption on systems with a large number of CPUs.

Change-Id: I458791aa8027cffeeec49698b302cb96ae5af2e2

manifests/wsgi/apache.pp

@@ -85,7 +85,7 @@
 #
 # [*threads*]
 #   (optional) The number of threads for the vhost.
-#   Defaults to $::processorcount
+#   Defaults to $::os_workers
 #
 # [*user*]
 #   (optional) User with permissions on the script
@@ -145,7 +145,7 @@ define openstacklib::wsgi::apache (
   $ssl_crl                 = undef,
   $ssl_crl_path            = undef,
   $ssl_key                 = undef,
-  $threads                 = $::processorcount,
+  $threads                 = $::os_workers,
   $user                    = undef,
   $workers                 = 1,
   $wsgi_daemon_process     = $name,

releasenotes/notes/os_workers_for_worker_count-34eb55ddf55f4a11.yaml

@@ -0,0 +1,5 @@
+---
+other:
+  - Parameters that control the number of spawned child processes for
+    distributing processing have had their default value changed from
+    ::processorcount to ::os_workers.

spec/defines/openstacklib_wsgi_apache_spec.rb

@@ -23,7 +23,7 @@ describe 'openstacklib::wsgi::apache' do
 
   let :global_facts do
     {
-      :processorcount => 42,
+      :os_workers     => 8,
       :concat_basedir => '/var/lib/puppet/concat',
       :fqdn           => 'some.host.tld'
     }
@@ -79,7 +79,7 @@ describe 'openstacklib::wsgi::apache' do
           'user'      => 'keystone',
           'group'     => 'keystone',
           'processes' => 1,
-          'threads'   => global_facts[:processorcount],
+          'threads'   => global_facts[:os_workers],
         },
         'wsgi_application_group'      => '%{GLOBAL}',
         'require'                     => 'File[keystone_wsgi]',
@@ -116,7 +116,7 @@ describe 'openstacklib::wsgi::apache' do
             'user'      => 'keystone',
             'group'     => 'keystone',
             'processes' => '37',
-            'threads'   => '42',
+            'threads'   => '8',
         },
         'wsgi_process_group'          => 'keystone_wsgi',
         'wsgi_script_aliases'         => { '/' => "/var/www/cgi-bin/keystone/main" },