Fix UDP server hanging on SIGINT due to untracked background tasks

server/udp_server.py

@@ -52,7 +52,9 @@ def connection_made(self, transport: asyncio.DatagramTransport):
     def datagram_received(self, data: bytes, addr: tuple):
         """Handle incoming UDP datagram."""
         # Schedule processing as a task to avoid blocking the protocol
-        asyncio.create_task(self.server.handle_packet(data, addr))
+        task = asyncio.create_task(self.server.handle_packet(data, addr))
+        self.server.background_tasks.add(task)
+        task.add_done_callback(lambda t: self.server.background_tasks.discard(t))
 
     def error_received(self, exc: Exception):
         print(f"UDP Error: {exc}")
@@ -98,6 +100,7 @@ def __init__(
         self.running = False
         self.transport: Optional[asyncio.DatagramTransport] = None
         self.protocol: Optional[UDPInputProtocol] = None
+        self.background_tasks: Set[asyncio.Task] = set()  # Track background tasks for cleanup
 
         # Player tracking
         self.player_addresses: Dict[str, tuple] = {}  # player_id -> (host, port)
@@ -136,8 +139,19 @@ async def stop(self):
         """Stop the UDP server and cleanup."""
         self.running = False
 
+        # Cancel all background tasks
+        for task in self.background_tasks:
+            task.cancel()
+
+        # Wait for all background tasks to complete with a timeout
+        if self.background_tasks:
+            await asyncio.gather(*self.background_tasks, return_exceptions=True)
+
+        # Close the transport
         if self.transport:
             self.transport.close()
+            # Give the transport a moment to flush and close cleanly
+            await asyncio.sleep(0.1)
             self.transport = None
 
         # Log final metrics