Set async event in async context

Author: davidbrochart

ipykernel/kernelapp.py

@@ -761,7 +761,7 @@ async def _start(self, backend: str) -> None:
 
     def start(self) -> None:
         """Start the application."""
-        backend = "trio" if self.trio_loop else "asyncio"
+        backend = "trio"# if self.trio_loop else "asyncio"
         run(partial(self._start, backend), backend=backend)
 
     async def _wait_to_enter_eventloop(self) -> None:

ipykernel/kernelbase.py

@@ -422,6 +422,11 @@ async def shell_main(self, subshell_id: str | None):
             if subshell_id is None:
                 # Main subshell.
                 await to_thread.run_sync(self.shell_stop.wait)
+
+                if not self._eventloop_set.is_set():
+                    # Stop the async task that is waiting for the eventloop to be set.
+                    self._eventloop_set.set()
+
                 tg.cancel_scope.cancel()
 
     async def process_shell(self, socket=None):
@@ -573,10 +578,6 @@ async def start(self, *, task_status: TaskStatus = TASK_STATUS_IGNORED) -> None:
                     tg.start_soon(self.shell_main, None)
 
     def stop(self):
-        if not self._eventloop_set.is_set():
-            # Stop the async task that is waiting for the eventloop to be set.
-            self._eventloop_set.set()
-
         self.shell_stop.set()
         self.control_stop.set()