revert %asyncio since it's not used in modern version ipykernel

Author: NewUserHa

ipykernel/eventloops.py

@@ -431,7 +431,6 @@ def loop_cocoa_exit(kernel):
 def loop_asyncio(kernel):
     """Start a kernel with asyncio event loop support."""
     import asyncio
-    import threading
 
     loop = asyncio.get_event_loop()
     # loop is already running (e.g. tornado 5), nothing left to do
@@ -452,25 +451,8 @@ def process_stream_events(shell_stream):
 
     shell_stream = get_shell_stream(kernel)
     notifier = partial(process_stream_events, shell_stream)
-
-    if os.name == "nt":
-        stop_event = asyncio.Event()
-        t = None
-
-        def blocking_poll():
-            poller = zmq.Poller()
-            poller.register(shell_stream.socket, zmq.POLLIN)
-
-            while not stop_event.is_set():
-                events = poller.poll(None)
-                if events:
-                    loop.call_soon_threadsafe(notifier)
-
-        t = threading.Thread(target=blocking_poll, daemon=True)
-        t.start()
-    else:
-        loop.add_reader(shell_stream.getsockopt(zmq.FD), notifier)
-        loop.call_soon(notifier)
+    loop.add_reader(shell_stream.getsockopt(zmq.FD), notifier)
+    loop.call_soon(notifier)
 
     while True:
         error = None
@@ -481,10 +463,6 @@ def blocking_poll():
         except Exception as e:
             error = e
         if loop._should_close:  # type:ignore[attr-defined]
-            if os.name == "nt":
-                stop_event.set()
-                if t is not None:
-                    t.join()
             loop.close()
         if error is not None:
             raise error