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/util/process.py

@@ -1,10 +1,9 @@
 import faulthandler
 import logging
 import multiprocessing as mp
-import signal
-import sys
 import threading
 from logging.handlers import QueueHandler
+from multiprocessing.synchronize import Event as MpEvent
 from typing import Callable, Optional
 
 from setproctitle import setproctitle
@@ -16,6 +15,7 @@ from frigate.config.logger import LoggerConfig
 class BaseProcess(mp.Process):
     def __init__(
         self,
+        stop_event: MpEvent,
         *,
         name: Optional[str] = None,
         target: Optional[Callable] = None,
@@ -23,6 +23,7 @@ class BaseProcess(mp.Process):
         kwargs: dict = {},
         daemon: Optional[bool] = None,
     ):
+        self.stop_event = stop_event
         super().__init__(
             name=name, target=target, args=args, kwargs=kwargs, daemon=daemon
         )
@@ -42,14 +43,6 @@ class BaseProcess(mp.Process):
 class FrigateProcess(BaseProcess):
     logger: logging.Logger
 
-    @property
-    def stop_event(self) -> threading.Event:
-        # Lazily create the stop_event. This allows the signal handler to tell if anyone is
-        # monitoring the stop event, and to raise a SystemExit if not.
-        if "stop_event" not in self.__dict__:
-            self.__dict__["stop_event"] = threading.Event()
-        return self.__dict__["stop_event"]
-
     def before_start(self) -> None:
         self.__log_queue = frigate.log.log_listener.queue
 
@@ -58,18 +51,7 @@ class FrigateProcess(BaseProcess):
         threading.current_thread().name = f"process:{self.name}"
         faulthandler.enable()
 
-        def receiveSignal(signalNumber, frame):
-            # Get the stop_event through the dict to bypass lazy initialization.
-            stop_event = self.__dict__.get("stop_event")
-            if stop_event is not None:
-                # Someone is monitoring stop_event. We should set it.
-                stop_event.set()
-            else:
-                # Nobody is monitoring stop_event. We should raise SystemExit.
-                sys.exit()
-
-        signal.signal(signal.SIGTERM, receiveSignal)
-        signal.signal(signal.SIGINT, receiveSignal)
+        # setup logging
         self.logger = logging.getLogger(self.name)
         logging.basicConfig(handlers=[], force=True)
         logging.getLogger().addHandler(QueueHandler(self.__log_queue))