Use daemon threads for background tasks in threading mode

src/engineio/async_drivers/threading.py

@@ -10,6 +10,11 @@
     _websocket_available = False
 
 
+class DaemonThread(threading.Thread):  # pragma: no cover
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs, daemon=True)
+
+
 class WebSocketWSGI(object):  # pragma: no cover
     """
     This wrapper class provides a threading WebSocket interface that is
@@ -43,7 +48,7 @@ def wait(self):
 
 
 _async = {
-    'thread': threading.Thread,
+    'thread': DaemonThread,
     'queue': queue.Queue,
     'queue_empty': queue.Empty,
     'event': threading.Event,

tests/common/test_server.py

@@ -101,11 +101,10 @@ def test_async_mode_threading(self):
         s = server.Server(async_mode='threading')
         assert s.async_mode == 'threading'
 
-        import threading
         from engineio.async_drivers import threading as async_threading
         import queue
 
-        assert s._async['thread'] == threading.Thread
+        assert s._async['thread'] == async_threading.DaemonThread
         assert s._async['queue'] == queue.Queue
         assert s._async['websocket'] == async_threading.WebSocketWSGI
         del sys.modules['simple_websocket']
@@ -115,10 +114,10 @@ def test_async_mode_threading_without_websocket(self):
         s = server.Server(async_mode='threading')
         assert s.async_mode == 'threading'
 
-        import threading
+        from engineio.async_drivers import threading as async_threading
         import queue
 
-        assert s._async['thread'] == threading.Thread
+        assert s._async['thread'] == async_threading.DaemonThread
         assert s._async['queue'] == queue.Queue
         assert s._async['websocket'] is None
         del sys.modules['engineio.async_drivers.threading']