apache wsgi: Exchange defaults for workers and threads

Due to Python's GIL [1], we can't use multiple threads for running
OpenStack services without a performance penalty, since the execution
ends up serialized, which defeats the purpose.

Instead, we should use several processes, since this approach doesn't
have this limitation.

[1] https://wiki.python.org/moin/GlobalInterpreterLock

Change-Id: I3edd574f60be594b18da78284831ffd19d2819f7

manifests/wsgi/apache.pp

@@ -42,7 +42,7 @@
 #
 #   [*workers*]
 #     Number of WSGI workers to spawn.
-#     Optional. Defaults to 1
+#     Optional. Defaults to $::os_workers
 #
 #   [*priority*]
 #     (optional) The priority for the vhost.
@@ -50,7 +50,7 @@
 #
 #   [*threads*]
 #     (optional) The number of threads for the vhost.
-#     Defaults to $::os_workers
+#     Defaults to 1
 #
 #   [*wsgi_process_display_name*]
 #     (optional) Name of the WSGI process display-name.
@@ -102,7 +102,7 @@ class cinder::wsgi::apache (
   $bind_host                   = undef,
   $path                        = '/',
   $ssl                         = true,
-  $workers                     = 1,
+  $workers                     = $::os_workers,
   $ssl_cert                    = undef,
   $ssl_key                     = undef,
   $ssl_chain                   = undef,
@@ -111,7 +111,7 @@ class cinder::wsgi::apache (
   $ssl_crl                     = undef,
   $ssl_certs_dir               = undef,
   $wsgi_process_display_name   = undef,
-  $threads                     = $::os_workers,
+  $threads                     = 1,
   $priority                    = '10',
   $access_log_file             = false,
   $access_log_format           = false,

spec/classes/cinder_wsgi_apache_spec.rb

@@ -14,9 +14,9 @@ describe 'cinder::wsgi::apache' do
         :path                        => '/',
         :servername                  => facts[:fqdn],
         :ssl                         => true,
-        :threads                     => facts[:os_workers],
+        :threads                     => 1,
         :user                        => 'cinder',
-        :workers                     => 1,
+        :workers                     => facts[:os_workers],
         :wsgi_daemon_process         => 'cinder-api',
         :wsgi_process_group          => 'cinder-api',
         :wsgi_script_dir             => platform_params[:wsgi_script_path],
@@ -56,7 +56,7 @@ describe 'cinder::wsgi::apache' do
         :path                      => '/',
         :servername                => 'dummy.host',
         :ssl                       => false,
-        :threads                   => facts[:os_workers],
+        :threads                   => 1,
         :user                      => 'cinder',
         :workers                   => 37,
         :wsgi_daemon_process       => 'cinder-api',