RustPython
diff --git a/‎Lib/selectors.py
Lines changed: 11 additions & 7 deletions b/‎Lib/selectors.py
Lines changed: 11 additions & 7 deletions
@@ -50,12 +50,11 @@ def _fileobj_to_fd(fileobj):
     Object used to associate a file object to its backing
     file descriptor, selected event mask, and attached data.
 """
-if sys.version_info >= (3, 5):
-    SelectorKey.fileobj.__doc__ = 'File object registered.'
-    SelectorKey.fd.__doc__ = 'Underlying file descriptor.'
-    SelectorKey.events.__doc__ = 'Events that must be waited for on this file object.'
-    SelectorKey.data.__doc__ = ('''Optional opaque data associated to this file object.
-    For example, this could be used to store a per-client session ID.''')
+SelectorKey.fileobj.__doc__ = 'File object registered.'
+SelectorKey.fd.__doc__ = 'Underlying file descriptor.'
+SelectorKey.events.__doc__ = 'Events that must be waited for on this file object.'
+SelectorKey.data.__doc__ = ('''Optional opaque data associated to this file object.
+For example, this could be used to store a per-client session ID.''')
 
 
 class _SelectorMapping(Mapping):
@@ -510,6 +509,7 @@ class KqueueSelector(_BaseSelectorImpl):
         def __init__(self):
             super().__init__()
             self._selector = select.kqueue()
+            self._max_events = 0
 
         def fileno(self):
             return self._selector.fileno()
@@ -521,10 +521,12 @@ def register(self, fileobj, events, data=None):
                     kev = select.kevent(key.fd, select.KQ_FILTER_READ,
                                         select.KQ_EV_ADD)
                     self._selector.control([kev], 0, 0)
+                    self._max_events += 1
                 if events & EVENT_WRITE:
                     kev = select.kevent(key.fd, select.KQ_FILTER_WRITE,
                                         select.KQ_EV_ADD)
                     self._selector.control([kev], 0, 0)
+                    self._max_events += 1
             except:
                 super().unregister(fileobj)
                 raise
@@ -535,6 +537,7 @@ def unregister(self, fileobj):
             if key.events & EVENT_READ:
                 kev = select.kevent(key.fd, select.KQ_FILTER_READ,
                                     select.KQ_EV_DELETE)
+                self._max_events -= 1
                 try:
                     self._selector.control([kev], 0, 0)
                 except OSError:
@@ -544,6 +547,7 @@ def unregister(self, fileobj):
             if key.events & EVENT_WRITE:
                 kev = select.kevent(key.fd, select.KQ_FILTER_WRITE,
                                     select.KQ_EV_DELETE)
+                self._max_events -= 1
                 try:
                     self._selector.control([kev], 0, 0)
                 except OSError:
@@ -556,7 +560,7 @@ def select(self, timeout=None):
             # If max_ev is 0, kqueue will ignore the timeout. For consistent
             # behavior with the other selector classes, we prevent that here
             # (using max). See https://bugs.python.org/issue29255
-            max_ev = max(len(self._fd_to_key), 1)
+            max_ev = self._max_events or 1
             ready = []
             try:
                 kev_list = self._selector.control(None, max_ev, timeout)