make sure we trigger all events.

following @saghul idea, start the spinner, pass it a dummy callback (lambda h:
None) and stop it at the end of _send. This will prevent the loop from
blocking for i/o on a given iteration if there are pending events, that is,
until the prepare handle is run. Als unref the prepare handle to not block the
loop.

gaffer/events.py

@@ -138,6 +138,9 @@ def __init__(self, loop, max_size=200):
         self._wqueue = deque(maxlen=max_size)
 
         self._event_dispatcher = pyuv.Prepare(self.loop)
+        self._event_dispatcher.start(self._send)
+        self._event_dispatcher.unref()
+
         self._spinner = pyuv.Idle(self.loop)
 
     def close(self):
@@ -225,9 +228,7 @@ def unsubscribe_all(self, events=[]):
     ### private methods
 
     def _dispatch_event(self):
-        if not self._event_dispatcher.active:
-            self._event_dispatcher.start(self._send)
-            self._spinner.start(lambda h: h.stop())
+        self._spinner.start(lambda h: None)
 
     def _send(self, handle):
         queue, self._queue = self._queue, deque(maxlen=self._queue.maxlen)
@@ -244,7 +245,7 @@ def _send(self, handle):
                 self._events[pattern] = self._send_listeners(evtype,
                     self._events[pattern].copy(), *args, **kwargs)
 
-        self._event_dispatcher.stop()
+        self._spinner.stop()
 
     def _send_listeners(self, evtype, listeners, *args, **kwargs):
         to_remove = []