refactor: execute in a separate thread (#110)

Just running async was still blocking the WebUI while a generation was running.

scripts/script.py

@@ -2,8 +2,9 @@
 
 from fastapi import FastAPI
 import gradio as gr
-from gradio.utils import run_coro_in_background
+import asyncio
 import requests
+from threading import Thread
 
 from modules import scripts, script_callbacks, sd_models, shared
 
@@ -15,16 +16,15 @@
 
 
 def on_app_started(demo: Optional[gr.Blocks], app: FastAPI):
-    import asyncio
-
     started = False
 
     @app.on_event("startup")
     @app.get("/horde/startup-events")
     async def startup_event():
         nonlocal started
         if not started:
-            run_coro_in_background(horde.run)
+            thread = Thread(daemon=True, target=horde_thread)
+            thread.start()
             started = True
 
     # This is a hack to make sure the startup event is
@@ -38,6 +38,10 @@ async def startup_event():
     requests.get(f"{local_url}horde/startup-events")
 
 
+def horde_thread():
+    asyncio.run(horde.run())
+
+
 def apply_stable_horde_settings(
     enable: bool,
     name: str,