Unify workers options for API services

This patch change behaviour of launching API services for different
numbers of workers:
- workers < 0 -> is not allowed
- workers == 0 -> as much worker *processes* as CPU cores
- workers == 1 -> no child *processes*, single *green thread*
- workers > 1 -> specified number of worker *processes*

Note: According with old behaviour following services have corresponding
defaul values:
 - heat-api  -> '0', instead of function for calculation number of cores.
 - heat-api-cfn -> '1', instead of '0' (i.e. one *green thread*)
 - heat-api-cw -> '1', instead of '0' (i.e. one *green thread*)

Also updated number of workers for functional tests.
It's necessary, because priveous value was '1', which now mean one
single thread. (Previously it was one worker).

Change-Id: Idebd19c62adea02d9181236f6cbfed090acb32b9
Closes-Bug: #1523390

heat/common/wsgi.py

@@ -76,8 +76,10 @@ api_opts = [
                help=_("Location of the SSL key file to use "
                       "for enabling SSL mode."),
                deprecated_group='DEFAULT'),
-    cfg.IntOpt('workers', default=processutils.get_worker_count(),
+    cfg.IntOpt('workers', default=0,
-               help=_("Number of workers for Heat service."),
+               help=_("Number of workers for Heat service. "
+                      "Default value 0 means, that service will start number "
+                      "of workers equal number of cores on server."),
                deprecated_group='DEFAULT'),
     cfg.IntOpt('max_header_line', default=16384,
                help=_('Maximum line size of message headers to be accepted. '
@@ -114,7 +116,7 @@ api_cfn_opts = [
                help=_("Location of the SSL key file to use "
                       "for enabling SSL mode."),
                deprecated_group='DEFAULT'),
-    cfg.IntOpt('workers', default=0,
+    cfg.IntOpt('workers', default=1,
                help=_("Number of workers for Heat service."),
                deprecated_group='DEFAULT'),
     cfg.IntOpt('max_header_line', default=16384,
@@ -152,7 +154,7 @@ api_cw_opts = [
                help=_("Location of the SSL key file to use "
                       "for enabling SSL mode."),
                deprecated_group='DEFAULT'),
-    cfg.IntOpt('workers', default=0,
+    cfg.IntOpt('workers', default=1,
                help=_("Number of workers for Heat service."),
                deprecated_group='DEFAULT'),
     cfg.IntOpt('max_header_line', default=16384,
@@ -310,17 +312,28 @@ class Server(object):
         self.start_wsgi()
 
     def start_wsgi(self):
-        if self.conf.workers == 0:
+        workers = self.conf.workers
+        # raise error if workers is incorrect value
+        if workers < 0:
+            raise ValueError("Number of workers should be more or equal '0'!")
+        # childs == num of cores
+        if workers == 0:
+            childs_num = processutils.get_worker_count()
+        # launch only one GreenPool without childs
+        elif workers == 1:
             # Useful for profiling, test, debug etc.
             self.pool = eventlet.GreenPool(size=self.threads)
             self.pool.spawn_n(self._single_run, self.application, self.sock)
             return
+        # childs equal specified value of workers
+        else:
+            childs_num = workers
 
-        LOG.info(_LI("Starting %d workers"), self.conf.workers)
+        LOG.info(_LI("Starting %d workers"), workers)
         signal.signal(signal.SIGTERM, self.kill_children)
         signal.signal(signal.SIGINT, self.kill_children)
         signal.signal(signal.SIGHUP, self.hup)
-        while len(self.children) < self.conf.workers:
+        while len(self.children) < childs_num:
             self.run_child()
 
     def wait_on_children(self):

heat_integrationtests/pre_test_hook.sh

@@ -30,9 +30,9 @@ echo -e 'notification_driver=messagingv2\n' >> $localconf
 echo -e 'hidden_stack_tags=hidden\n' >> $localconf
 echo -e 'encrypt_parameters_and_properties=True\n' >> $localconf
 
-echo -e '[heat_api]\nworkers=1\n' >> $localconf
+echo -e '[heat_api]\nworkers=2\n' >> $localconf
-echo -e '[heat_api_cfn]\nworkers=1\n' >> $localconf
+echo -e '[heat_api_cfn]\nworkers=2\n' >> $localconf
-echo -e '[heat_api_cloudwatch]\nworkers=1\n' >> $localconf
+echo -e '[heat_api_cloudwatch]\nworkers=2\n' >> $localconf
 
 echo -e '[cache]\nenabled=True\n' >> $localconf