Configure Docker to use Gunicorn instead of Flask development server for production deployment. Updated SocketIO configuration for gevent compatibility.

app/__init__.py

@@ -12,9 +12,10 @@ from config import config
 from app.models import SimulationManager
 
 # Initialize SocketIO with enhanced proxy support
+# For Gunicorn compatibility, we need to set the async_mode to 'gevent'
 socketio = SocketIO(
     cors_allowed_origins="*",
-    async_mode='threading',
+    async_mode='gevent' if os.getenv('FLASK_ENV') == 'production' else 'threading',
     logger=False,  # Disable to avoid log spam in production
     engineio_logger=False,
     # Transport order: try websocket first, then polling
@@ -54,7 +55,7 @@ def create_app(config_name=None):
     # Initialize extensions with proxy-friendly settings
     socketio.init_app(
         app, 
-        async_mode='threading',
+        async_mode='gevent' if config_name == 'production' else 'threading',
         cors_allowed_origins="*",
         allow_upgrades=True,
         transports=['websocket', 'polling'],