Handle SIGINT with forkserver (#18860)

* Pass stopevent from main start

* Share stop event across processes

* preload modules

* remove explicit os._exit call

---------

Co-authored-by: Josh Hawkins <32435876+hawkeye217@users.noreply.github.com>

frigate/__main__.py

@@ -23,6 +23,10 @@ def main() -> None:
     setup_logging(manager)
 
     threading.current_thread().name = "frigate"
+    stop_event = mp.Event()
+
+    # send stop event on SIGINT
+    signal.signal(signal.SIGINT, lambda sig, frame: stop_event.set())
 
     # Make sure we exit cleanly on SIGTERM.
     signal.signal(signal.SIGTERM, lambda sig, frame: sys.exit())
@@ -110,9 +114,23 @@ def main() -> None:
         sys.exit(0)
 
     # Run the main application.
-    FrigateApp(config, manager).start()
+    FrigateApp(config, manager, stop_event).start()
 
 
 if __name__ == "__main__":
+    mp.set_forkserver_preload(
+        [
+            # Standard library and core dependencies
+            "sqlite3",
+            # Third-party libraries commonly used in Frigate
+            "numpy",
+            "cv2",
+            "peewee",
+            "zmq",
+            "ruamel.yaml",
+            # Frigate core modules
+            "frigate.camera.maintainer",
+        ]
+    )
     mp.set_start_method("forkserver", force=True)
     main()