Hold references to background tasks to avoid garbage collection

src/engineio/async_client.py

@@ -15,6 +15,11 @@
 
 async_signal_handler_set = False
 
+# this set is used to keep references to background tasks to prevent them from
+# being garbage collected mid-execution. Solution taken from
+# https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task
+task_reference_holder = set()
+
 
 def async_signal_handler():
     """SIGINT handler.
@@ -450,8 +455,11 @@ async def _trigger_event(self, event, *args, **kwargs):
         if event in self.handlers:
             if asyncio.iscoroutinefunction(self.handlers[event]) is True:
                 if run_async:
-                    return self.start_background_task(self.handlers[event],
+                    task = self.start_background_task(self.handlers[event],
                                                       *args)
+                    task_reference_holder.add(task)
+                    task.add_done_callback(task_reference_holder.discard)
+                    return task
                 else:
                     try:
                         ret = await self.handlers[event](*args)
@@ -468,7 +476,10 @@ async def _trigger_event(self, event, *args, **kwargs):
                     async def async_handler():
                         return self.handlers[event](*args)
 
-                    return self.start_background_task(async_handler)
+                    task = self.start_background_task(async_handler)
+                    task_reference_holder.add(task)
+                    task.add_done_callback(task_reference_holder.discard)
+                    return task
                 else:
                     try:
                         ret = self.handlers[event](*args)

src/engineio/async_server.py

@@ -6,6 +6,11 @@
 from . import packet
 from . import async_socket
 
+# this set is used to keep references to background tasks to prevent them from
+# being garbage collected mid-execution. Solution taken from
+# https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task
+task_reference_holder = set()
+
 
 class AsyncServer(base_server.BaseServer):
     """An Engine.IO server for asyncio.
@@ -487,6 +492,8 @@ async def run_async_handler():
 
                 if run_async:
                     ret = self.start_background_task(run_async_handler)
+                    task_reference_holder.add(ret)
+                    ret.add_done_callback(task_reference_holder.discard)
                 else:
                     ret = await run_async_handler()
             else:
@@ -502,6 +509,8 @@ async def run_sync_handler():
 
                 if run_async:
                     ret = self.start_background_task(run_sync_handler)
+                    task_reference_holder.add(ret)
+                    ret.add_done_callback(task_reference_holder.discard)
                 else:
                     ret = await run_sync_handler()
         return ret