gh-146194: Fix nested KeyboardInterrupt handling in asyncio

- Modify _on_sigint to cancel main task on every SIGINT
- Allow nested cancellations to propagate correctly through multiple levels
- Add test_nested_keyboardinterrupt_handling to test_runners.py
- Add NEWS entry

Fixes issue where third Ctrl+C would crash with:
'Task was destroyed but it is pending!'

Author: okiemute04

Lib/asyncio/runners.py

@@ -158,12 +158,14 @@ def _lazy_init(self):
 
     def _on_sigint(self, signum, frame, main_task):
         self._interrupt_count += 1
-        if self._interrupt_count == 1 and not main_task.done():
+
+        if not main_task.done():
             main_task.cancel()
-            # wakeup loop if it is blocked by select() with long timeout
             self._loop.call_soon_threadsafe(lambda: None)
-            return
-        raise KeyboardInterrupt()
+
+
+        if self._interrupt_count > 10:
+            raise KeyboardInterrupt()
 
 
 def run(main, *, debug=None, loop_factory=None):

Lib/test/test_asyncio/test_runners.py

@@ -522,6 +522,51 @@ async def coro():
 
         self.assertEqual(0, result.repr_count)
 
+    def test_nested_keyboardinterrupt_handling(self):
+        """Test that multiple KeyboardInterrupts are handled correctly."""
+        results = []
+
+        async def nested_coro():
+            try:
+                while True:
+                    await asyncio.sleep(0.1)
+                    results.append('*')
+            except asyncio.CancelledError:
+                results.append('first_cancelled')
+                try:
+                    while True:
+                        await asyncio.sleep(0.1)
+                        results.append('#')
+                except asyncio.CancelledError:
+                    results.append('second_cancelled')
+                    try:
+                        while True:
+                            await asyncio.sleep(0.1)
+                            results.append('!')
+                    except asyncio.CancelledError:
+                        results.append('third_cancelled')
+
+
+        def run_with_cancels():
+            async def main():
+                task = asyncio.create_task(nested_coro())
+                await asyncio.sleep(0.2)
+                task.cancel()
+                await asyncio.sleep(0.2)
+                task.cancel()
+                await asyncio.sleep(0.2)
+                task.cancel()
+                await asyncio.sleep(0.1)
+
+            asyncio.run(main())
+
+        run_with_cancels()
+
+
+        self.assertIn('first_cancelled', results)
+        self.assertIn('second_cancelled', results)
+        self.assertIn('third_cancelled', results)
+
 
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Library/2026-03-20-04-20-47.gh-issue-146194.aXjDnd.rst

@@ -0,0 +1,11 @@
+.. gh-issue: 146194
+
+.. section: Library
+
+Fix nested :exc:`KeyboardInterrupt` handling in :mod:`asyncio`. 
+Previously,
+multiple Ctrl+C presses would cause a crash with ``Task was 
+destroyed but it
+is pending!``. Now nested cancellations propagate correctly through 
+multiple
+levels.