Concurrence & Exécution Asynchrone

FastAPI s'appuie sur une boucle d'événements asynchrone (asyncio). Les opérations bloquantes (calculs pandas, appels ORM ou requêtes HTTP synchrones) ne doivent jamais s'exécuter directement sur le thread principal de la boucle d'événements.

The run_sync Helper (concurrency.py)

Fonrex provides run_sync() in concurrency.py as a unified abstraction for executing blocking synchronous code safely inside worker threads:

from concurrency import run_sync

# Offloads a synchronous blocking function to the default ThreadPoolExecutor
result = await run_sync(sync_blocking_function, arg1, arg2, kwarg=value)

Architecture Interne

FastAPI Event Loop (Async)
       │
       ├─► Async HTTP Router Endpoint (async def)
       │         │
       │         ├─► Calls run_sync(DatabaseService.get_asset, ticker)
       │         │         │
       │         │         ▼
       │         │   ThreadPoolExecutor Worker Thread
       │         │   (Exécute une requête ORM SQLAlchemy synchrone)
       │         │         │
       │         │   ◄─────┘
       │         │
       │   ◄─────┘ Event Loop remains unblocked for other requests!
       │
       └─► Processes other concurrent HTTP / WS connections

Directives pour les Développeurs

1. Async Routers: Define router functions with async def.
2. Synchronous Services: If a service method interacts with DatabaseService or yfinance, invoke it via await run_sync(service.method, ...) from the router.
3. Async Services: Services that utilize redis.asyncio or httpx.AsyncClient (NewsService, CanaryMonitor) can be awaited directly without run_sync.