Fix graceful shutdown to wait for download/install worker threads

invokeai/app/run_app.py

@@ -9,8 +9,6 @@ def get_app():
 
 def run_app() -> None:
     """The main entrypoint for the app."""
-    import os
-
     from invokeai.frontend.cli.arg_parser import InvokeAIArgs
 
     # Parse the CLI arguments before doing anything else, which ensures CLI args correctly override settings from other
@@ -106,5 +104,8 @@ def run_app() -> None:
         loop.run_until_complete(server.serve())
     except KeyboardInterrupt:
         logger.info("InvokeAI shutting down...")
-        # Force exit to avoid hanging on non-daemon background threads (e.g. model install service).
-        os._exit(0)
+        # Gracefully shut down services (e.g. model download and install managers) so that any
+        # active work is completed or cleanly cancelled before the process exits.
+        from invokeai.app.api.dependencies import ApiDependencies
+
+        ApiDependencies.shutdown()

invokeai/app/services/download/download_default.py

@@ -88,7 +88,7 @@ def stop(self, *args: Any, **kwargs: Any) -> None:
         """Stop the download worker threads."""
         with self._lock:
             if not self._worker_pool:
-                raise Exception("Attempt to stop the download service before it was started")
+                return
             self._accept_download_requests = False  # reject attempts to add new jobs to queue
             queued_jobs = [x for x in self.list_jobs() if x.status == DownloadJobStatus.WAITING]
             active_jobs = [x for x in self.list_jobs() if x.status == DownloadJobStatus.RUNNING]

invokeai/app/services/model_install/model_install_default.py

@@ -313,7 +313,7 @@ def start(self, invoker: Optional[Invoker] = None) -> None:
     def stop(self, invoker: Optional[Invoker] = None) -> None:
         """Stop the installer thread; after this the object can be deleted and garbage collected."""
         if not self._running:
-            raise Exception("Attempt to stop the install service before it was started")
+            return
         self._logger.debug("calling stop_event.set()")
         self._stop_event.set()
         self._clear_pending_jobs()