Turn on multi-threading for FMN backend.

roles/notifs/backend/templates/fmn.consumer.py

@@ -22,6 +22,11 @@ config = {
     "fmn.consumer.enabled": True,
     "fmn.sqlalchemy.uri": "postgresql://{{notifs_db_user}}:{{notifs_db_password}}@db-notifs/notifications",
 
+    # This sets up four threads to handle incoming messages.  At the time of
+    # this commit, all of our fedmsg daemons are running in single-threaded
+    # mode.  If we turn it on globally, we should remove this setting.
+    "moksha.threads_per_consumer": 4,
+
     # Some configuration for the rule processors
     "fmn.rules.utils.use_pkgdb2": True,
     {% if env == 'staging' %}