Example using Celery for plugin queue

Procfile

@@ -1,3 +1,3 @@
 web: manage.py runserver $WEB_PORT
-plugins: manage.py run_plugins
+plugins: celery -A botbot worker -l info
 bot: botbot-bot -v=2 -logtostderr=true

botbot/__init__.py

@@ -0,0 +1,5 @@
+from __future__ import absolute_import
+
+# This will make sure the app is always imported when
+# Django starts so that shared_task will use this app.
+from .celery import app as celery_app

botbot/apps/plugins/runner.py

@@ -131,10 +131,7 @@ class PluginRunner(object):
     Calls to plugins are done via greenlets
     """
 
-    def __init__(self, use_gevent=False):
-        if use_gevent:
-            import gevent
-            self.gevent = gevent
+    def __init__(self):
         self.bot_bus = redis.StrictRedis.from_url(
             settings.REDIS_PLUGIN_QUEUE_URL)
         self.storage = redis.StrictRedis.from_url(
@@ -176,32 +173,15 @@ def register(self, plugin):
                 getattr(self, attr.route_rule[0] + '_router').setdefault(
                     plugin.slug, []).append((attr.route_rule[1], attr, plugin))
 
-    def listen(self):
-        """Listens for incoming messages on the Redis queue"""
-        while 1:
-            val = None
-            try:
-                val = self.bot_bus.blpop('q', 1)
-
-                # Track q length
-                ql = self.bot_bus.llen('q')
-                statsd.gauge(".".join(["plugins", "q"]), ql)
-
-                if val:
-                    _, val = val
-                    LOG.debug('Recieved: %s', val)
-                    line = Line(json.loads(val), self)
-
-                    # Calculate the transport latency between go and the plugins.
-                    delta = datetime.utcnow().replace(tzinfo=utc) - line._received
-                    statsd.timing(".".join(["plugins", "latency"]),
-                                 delta.total_seconds() * 1000)
+    def process_line(self, line_json):
+        LOG.debug('Recieved: %s', line_json)
+        line = Line(json.loads(line_json), self)
+        # Calculate the transport latency between go and the plugins.
+        delta = datetime.utcnow().replace(tzinfo=utc) - line._received
+        statsd.timing(".".join(["plugins", "latency"]),
+                      delta.total_seconds() * 1000)
+        self.dispatch(line)
 
-                    self.dispatch(line)
-            except Exception:
-                LOG.error("Line Dispatch Failed", exc_info=True, extra={
-                    "line": val
-                })
 
     def dispatch(self, line):
         """Given a line, dispatch it to the right plugins & functions."""
@@ -214,16 +194,11 @@ def dispatch(self, line):
                 # firehose gets everything, no rule matching
                 LOG.info('Match: %s.%s', plugin_slug, func.__name__)
                 with statsd.timer(".".join(["plugins", plugin_slug])):
-                    # FIXME: This will not have correct timing if go back to
-                    # gevent.
                     channel_plugin = self.setup_plugin_for_channel(
                         plugin.__class__, line)
                     new_func = log_on_error(LOG, getattr(channel_plugin,
                                                          func.__name__))
-                    if hasattr(self, 'gevent'):
-                        self.gevent.Greenlet.spawn(new_func, line)
-                    else:
-                        channel_plugin.respond(new_func(line))
+                    channel_plugin.respond(new_func(line))
 
         # pass line to other routers
         if line._is_message:
@@ -252,30 +227,12 @@ def check_for_plugin_route_matches(self, line, router):
                 if match:
                     LOG.info('Match: %s.%s', plugin_slug, func.__name__)
                     with statsd.timer(".".join(["plugins", plugin_slug])):
-                        # FIXME: This will not have correct timing if go back to
-                        # gevent.
                         # Instantiate a plugin specific to this channel
                         channel_plugin = self.setup_plugin_for_channel(
                             plugin.__class__, line)
                         # get the method from the channel-specific plugin
                         new_func = log_on_error(LOG, getattr(channel_plugin,
                                                              func.__name__))
-                        if hasattr(self, 'gevent'):
-                            grnlt = self.gevent.Greenlet(new_func, line,
-                                                         **match.groupdict())
-                            grnlt.link_value(channel_plugin.greenlet_respond)
-                            grnlt.start()
-                        else:
-                            channel_plugin.respond(new_func(line,
-                                                            **match.groupdict()))
 
-
-def start_plugins(*args, **kwargs):
-    """
-    Used by the management command to start-up plugin listener
-    and register the plugins.
-    """
-    LOG.info('Starting plugins. Gevent=%s', kwargs['use_gevent'])
-    app = PluginRunner(**kwargs)
-    app.register_all_plugins()
-    app.listen()
+                        channel_plugin.respond(new_func(line,
+                                                        **match.groupdict()))

botbot/apps/plugins/tasks.py

@@ -0,0 +1,14 @@
+from botbot.celery import app
+from .runner import PluginRunner
+
+
+runner = PluginRunner()
+runner.register_all_plugins()
+
+@app.task(bind=True)
+def route_line(self, line_json):
+    try:
+        runner.process_line(line_json)
+    # For any error we retry after 10 seconds.
+    except Exception as exc:
+        raise self.retry(exc, countdown=10)

botbot/celery.py

@@ -0,0 +1,16 @@
+from __future__ import absolute_import
+
+import os
+
+from celery import Celery
+
+os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'botbot.settings')
+
+from django.conf import settings
+
+app = Celery('botbot')
+
+# Using a string here means the worker will not have to
+# pickle the object when using Windows.
+app.config_from_object('django.conf:settings')
+app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

botbot/settings/base.py

@@ -272,7 +272,9 @@
 # Third party app settings
 # ==============================================================================
 
-# SOUTH_DATABASE_ADAPTERS = {'default': 'south.db.postgresql_psycopg2'}
+CELERY_TASK_SERIALIZER='json'
+CELERY_ACCEPT_CONTENT=['json']
+BROKER_URL = REDIS_PLUGIN_QUEUE_URL
 
 SOCIAL_AUTH_USER_MODEL = AUTH_USER_MODEL
 SOCIAL_AUTH_PROTECTED_USER_FIELDS = ['email']

manage.py

@@ -2,11 +2,6 @@
 import sys
 
 if __name__ == "__main__":
-    if (len(sys.argv) > 1 and
-            'run_plugins' in sys.argv and '--with-gevent' in sys.argv):
-        # import gevent as soon as possible
-        from gevent import monkey; monkey.patch_all()
-        from psycogreen.gevent import patch_psycopg; patch_psycopg()
 
     import os
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "botbot.settings")

requirements.txt

@@ -1,4 +1,5 @@
 django==1.7.2
+celery==3.1.18
 
 pytz
 psycopg2==2.5.2