Save a tiny bit of memory in events by clearing the notifier.

It would become False anyway as soon as the method returned. We won't
schedule another one while it's running (True), so there's no race
condition.

gevent/corecffi.py

@@ -452,7 +452,9 @@ class loop(object):
                         except: # pylint:disable=bare-except
                             pass # Nothing we can do here
                 finally:
-                    # Note, this must be reset here, because cb.args is used as a flag in callback class,
+                    # NOTE: this must be reset here, because cb.args is used as a flag in
+                    # the callback class so that bool(cb) of a callback that has been run
+                    # becomes False
                     cb.args = None
                     count -= 1
         if self._callbacks:
@@ -681,13 +683,16 @@ class callback(object):
         self.callback = None
         self.args = None
 
-    # Note, that __nonzero__ and pending are different
-    # nonzero is used in contexts where we need to know whether to schedule another callback,
+    # Note that __nonzero__ and pending are different
+    # bool() is used in contexts where we need to know whether to schedule another callback,
     # so it's true if it's pending or currently running
-    # 'pending' has the same meaning as libev watchers: it is cleared before entering callback
+    # 'pending' has the same meaning as libev watchers: it is cleared before actually
+    # running the callback
 
     def __nonzero__(self):
         # it's nonzero if it's pending or currently executing
+        # NOTE: This depends on loop._run_callbacks setting the args property
+        # to None.
         return self.args is not None
     __bool__ = __nonzero__
 

gevent/event.py

@@ -81,6 +81,10 @@ class _AbstractLinkable(object):
                 except: # pylint:disable=bare-except
                     self.hub.handle_error((link, self), *sys.exc_info())
 
+        # save a tiny bit of memory by letting _notifier be collected
+        # bool(self._notifier) would turn to False as soon as we exit this
+        # method anyway.
+        del self._notifier
 
     def _wait_core(self, timeout, catch=Timeout):
         # The core of the wait implementation, handling