pool_test.py

from flask import Flask
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
import time

app = Flask(__name__)
engine = create_engine('mysql+pymysql://root:22380476@localhost/pool?charset=UTF8MB4', pool_recycle=300)
SessionMaker = sessionmaker(bind=engine)
engine.execute('SELECT NOW();')

@app.route('/')
def index():
    session = SessionMaker()
    print(engine.pool.status())
    time.sleep(0.3)
    return 'Hello World'

if __name__ == '__main__':
    app.run()