Issue #20505: BaseEventLoop uses again the resolution of the clock to decide if
scheduled tasks should be executed or not.
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 4207a7e..377ea21 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -96,6 +96,7 @@
         self._default_executor = None
         self._internal_fds = 0
         self._running = False
+        self._clock_resolution = time.get_clock_info('monotonic').resolution
 
     def _make_socket_transport(self, sock, protocol, waiter=None, *,
                                extra=None, server=None):
@@ -643,10 +644,10 @@
         self._process_events(event_list)
 
         # Handle 'later' callbacks that are ready.
-        now = self.time()
+        end_time = self.time() + self._clock_resolution
         while self._scheduled:
             handle = self._scheduled[0]
-            if handle._when > now:
+            if handle._when >= end_time:
                 break
             handle = heapq.heappop(self._scheduled)
             self._ready.append(handle)