为什么flask url_for太慢

I tested it with this code:

我用这个代码测试了它:

from gevent import wsgi, monkey; monkey.patch_all()
from flask import Flask, url_for

app = Flask(__name__)

@app.route('/<int:n>')
def index(n):
    for i in xrange(n):
        url = url_for('index', n=i)
    return url 

wsgi.WSGIServer(('', 8000), app).serve_forever()
fro