[BUG] `docker restart` fails die to Process ID file already exists + slow shutdown
**Describe the bug**
Running `docker restart CONTAINER_NAME` we get:

```
None of PyTorch, TensorFlow >= 2.0, or Flax have been found. Models won't be available and only tokenizers, configuration and file/data utilities can be used.
Loading environment from .env
Loading environment from /opt/gpt3discord/etc/environment
Loading environment from None
Attempting to retrieve the General and Moderations DB
Retrieved the General and Moderations DB
Attempting to retrieve the General and Moderations DB
Process ID file already exists
```

**To Reproduce**
Steps to reproduce the behavior:
1. Run `docker restart $CONTAINER_NAME`

**Expected behavior**
Faster restart and process file to be cleaned up

**Additional context**
I will eventually debug and fix - But logging the job in case someone beats me.
diff --git a/gpt3discord.py b/gpt3discord.py
index 86c9ce5..b8f7b1a 100644
--- a/gpt3discord.py
+++ b/gpt3discord.py
@@ -1,5 +1,6 @@
 import os
 import asyncio
+import signal
 import sys
 import threading
 import traceback
@@ -29,6 +30,8 @@ from models.openai_model import Model
 
 __version__ = "8.3.5"
 
+PID_FILE = Path("bot.pid")
+PROCESS = None
 
 if sys.platform == "win32":
     separator = "\\\\"
@@ -173,22 +176,53 @@ async def main():
     await bot.start(os.getenv("DISCORD_TOKEN"))
 
 
+def check_process_file(pid_file: Path) -> bool:
+    """Check the pid file exists and if the Process ID is actually running"""
+    if not pid_file.exists():
+        return False
+    if system() == "Linux":
+        with pid_file.open("r") as pfp:
+            try:
+                proc_pid_path = Path("/proc") / "{int(pfp.read().strip())}"
+                print("Checking if PID proc path {proc_pid_path} exists")
+            except ValueError:
+                # We don't have a valid int in the PID File^M
+                pid_file.unlink()
+                return False
+        return proc_pid_path.exists()
+    return True
+
+
+def cleanup_pid_file(signum, frame):
+    # Kill all threads
+    if PROCESS:
+        print("Killing all subprocesses")
+        PROCESS.terminate()
+    print("Killed all subprocesses")
+    # Always cleanup PID File if it exists
+    if PID_FILE.exists():
+        print(f"Removing PID file {PID_FILE}", flush=True)
+        PID_FILE.unlink()
+
+
 # Run the bot with a token taken from an environment file.
 def init():
-    PID_FILE = "bot.pid"
-    process = None
-    if os.path.exists(PID_FILE):
+    global PROCESS
+    # Handle SIGTERM cleanly - Docker sends this ...
+    signal.signal(signal.SIGTERM, cleanup_pid_file)
+
+    if check_process_file(PID_FILE):
         print("Process ID file already exists")
         sys.exit(1)
     else:
-        with open(PID_FILE, "w") as f:
+        with PID_FILE.open("w") as f:
             f.write(str(os.getpid()))
-            print("" "Wrote PID to f" "ile the file " + PID_FILE)
+            print(f"Wrote PID to file {PID_FILE}")
             f.close()
     try:
         if EnvService.get_health_service_enabled():
             try:
-                process = HealthService().get_process()
+                PROCESS = HealthService().get_process()
             except:
                 traceback.print_exc()
                 print("The health service failed to start.")
@@ -196,19 +230,14 @@ def init():
         asyncio.get_event_loop().run_until_complete(main())
     except KeyboardInterrupt:
         print("Caught keyboard interrupt, killing and removing PID")
-        os.remove(PID_FILE)
     except Exception as e:
         traceback.print_exc()
         print(str(e))
         print("Removing PID file")
-        os.remove(PID_FILE)
     finally:
-        # Kill all threads
-        if process:
-            print("Killing all subprocesses")
-            process.terminate()
-        print("Killed all subprocesses")
-        sys.exit(0)
+        cleanup_pid_file(None, None)
+
+    sys.exit(0)
 
 
 if __name__ == "__main__":

['gpt3discord.py']