如何在启用多进程的Flask应用中使用全局变量

from multiprocessing import Value
from flask import Flask

app = Flask(__name__)
counter = Value('i', 0)

@app.route('/')
def index():
    with counter.get_lock():
        counter.value += 1
    return f'Counter: {counter.value}'

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

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://username:password@localhost/db_name'
db = SQLAlchemy(app)

class GlobalVariable(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), unique=True)
    value = db.Column(db.String(50))

@app.route('/')
def index():
    variable = GlobalVariable.query.filter_by(name='counter').first()
    if variable is None:
        variable = GlobalVariable(name='counter', value='0')
        db.session.add(variable)
    else:
        variable.value = str(int(variable.value) + 1)
    db.session.commit()
    return f'Counter: {variable.value}'

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