WSGIMiddleware overhead

main.py

from a2wsgi import WSGIMiddleware
from fastapi import FastAPI
from fastapi.responses import ORJSONResponse, UJSONResponse
from flask import Flask
from sqlalchemy.pool import StaticPool
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base

flask_app = Flask(__name__)

app = FastAPI()

DATABASE_URL = "sqlite://"
db = create_engine(DATABASE_URL, connect_args={"check_same_thread": False}, poolclass=StaticPool)
Session = sessionmaker(bind=db)
Base = declarative_base()


class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True)
    name = Column(String, nullable=False, unique=True)


def get_users():
    session = Session()
    users = session.query(User).all()
    return {"users": [{"name": user.name} for user in users]}


@flask_app.route("/users_flask")
def users_flask():
    return get_users()


@app.get("/users_fastapi", response_class=ORJSONResponse)
async def users_fastapi():
    return get_users()


def init_db():
    Base.metadata.create_all(db)
    session = Session()

    for i in range(5000):
        session.execute(
            User.__table__.insert(),
            [
                {"name": "user{}".format(i)},
            ],
        )
    session.commit()

app.mount("/", WSGIMiddleware(flask_app))

init_db()

note.md

uvicorn

uvicorn main:app --port 8000 --no-access-log  --workers 1

$ wrk http://127.0.0.1:8000/users_fastapi

Running 10s test @ http://127.0.0.1:8000/users_fastapi
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   568.68ms   68.02ms 637.11ms   95.32%
    Req/Sec    12.06      7.11    20.00     36.21%
  171 requests in 10.01s, 16.15MB read
Requests/sec:     17.08
Transfer/sec:      1.61MB

$ wrk http://127.0.0.1:8000/users_flask

Running 10s test @ http://127.0.0.1:8000/users_flask
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.24s   157.89ms   1.56s    77.03%
    Req/Sec     7.58      5.52    20.00     64.06%
  74 requests in 10.01s, 6.99MB read
Requests/sec:      7.39
Transfer/sec:    714.88KB