FastAPILifespan quản lý resource cấp app như connection pool, cache client, ML model hoặc scheduler. Code trước yield chạy khi app startup, code sau yield chạy khi shutdown, giúp mở và đóng resource đúng vòng đời.
Ví dụ:
python
@asynccontextmanager
async def lifespan(app: FastAPI):
app.state.redis = await Redis.from_url(REDIS_URL)
yield
await app.state.redis.aclose()
app = FastAPI(lifespan=lifespan)Không nên tạo resource nặng ở global import nếu nó cần cleanup hoặc phụ thuộc cấu hình runtime.
Lifespan manages app-level resources such as connection pools, cache clients, ML models or schedulers. Code before yield runs at startup; code after yield runs at shutdown, so resources open and close with the app lifecycle.
Example:
python
@asynccontextmanager
async def lifespan(app: FastAPI):
app.state.redis = await Redis.from_url(REDIS_URL)
yield
await app.state.redis.aclose()
app = FastAPI(lifespan=lifespan)Do not create heavy resources at global import time if they need cleanup or depend on runtime configuration.