refactor: replace threading with multiprocessing

app.py

@@ -4,12 +4,20 @@ Refactored modular architecture for computer vision pipeline processing.
 """
 import json
 import logging
+import multiprocessing as mp
 import os
 import time
 from contextlib import asynccontextmanager
 from fastapi import FastAPI, WebSocket, HTTPException, Request
 from fastapi.responses import Response
 
+# Set multiprocessing start method to 'spawn' for uvicorn compatibility
+if __name__ != "__main__":  # When imported by uvicorn
+    try:
+        mp.set_start_method('spawn', force=True)
+    except RuntimeError:
+        pass  # Already set
+
 # Import new modular communication system
 from core.communication.websocket import websocket_endpoint
 from core.communication.state import worker_state
@@ -85,10 +93,9 @@ else:
 os.makedirs("models", exist_ok=True)
 logger.info("Ensured models directory exists")
 
-# Initialize stream manager with config value
-from core.streaming import initialize_stream_manager
-initialize_stream_manager(max_streams=config.get('max_streams', 10))
-logger.info(f"Initialized stream manager with max_streams={config.get('max_streams', 10)}")
+# Stream manager is already initialized with multiprocessing in manager.py
+# (shared_stream_manager is created with max_streams=20 from config)
+logger.info(f"Using pre-configured stream manager with max_streams={config.get('max_streams', 20)}")
 
 # Store cached frames for REST API access (temporary storage)
 latest_frames = {}