Fastapi: @app.middleware("http")

[littleforce163]

@app.middleware("http")

I quote middleware to calculate the process time, while I find the requests per second (RPS) to be 60% of without middleware. That means 4000rps to around 2500rps. Is it right?
Could you please give some advice to improve the performance of middleware?

@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    start_timestamp = time.time()
    request.state.timestamp = start_timestamp
    response = await call_next(request)
    process_time = time.time() - start_timestamp
    response.headers["X-Process-Time"] = str(process_time)
    logger.info({"status_code": response.status_code,
                 "url": request.url,
                 "client": request.client.host,
                 "timestamp": start_timestamp,
                 "process_time": process_time})
    return response

[Kludex]

It's a known issue on Starlette side.

When you create a middleware using the decorator @app.middleware('http') it creates a BaseHTTPMiddleware based middleware. Precisely the class that comes with the issue (https://github.com/encode/starlette/issues/919).

You should create a pure ASGI middleware. I'm going to recommend this middleware tho: TimingMiddleware.

The FastAPI @app.add_middleware is inherited from Starlette, so you should be able to do as: https://github.com/steinnes/timing-asgi#usage.

Note:
There's an issue on Starlette side to improve the documentation about middlewares. So, I think a PR will be gladly accepted by @tiangolo (those are my words, not his, jfyk) if someone wants to improve the documentation about it on Advanced Middleware section on FastAPI itself.

[littleforce163]

Thank you, Kludex！Maybe an wrapper will works well. Hope to hear good news soon.