如何将 mysql.connection db pool 与 python flask 一起使用

Question

我在 mysql 5.6 中使用了 Flask 10.1。我想要一个连接池，单个请求可以在其中获取连接并并行插入数据。我认为应该工作的代码是这样的：

# !flask/bin/python
from flask import Flask, jsonify, abort, make_response, request, g
import mysql.connector

app = Flask(__name__)

db_user = "user"
db_pass = "pass"
db_url = "127.0.0.1"


@app.before_first_request
def before_first_request():
    # configure the connection pool in the global object
    g.cnx_pool = mysql.connector.pooling.MySQLConnectionPool(pool_name="name",
                                                             pool_size=10,
                                                             autocommit=True,
                                                             user=db_user,
                                                             password=db_pass,
                                                             host=db_url,
                                                             database='db')

@app.route('/log', methods=['POST'])
def log_data():
    """
    Logs data
    """
    cursor = g.cnx_pool.get_connection().cursor()
    query = """INSERT INTO db.data (time,data) values (NOW(),%s)"""
    cursor.execute(query, (request.get_data(),))
    return make_response('', 200)

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

但是，我在 g 中存储的全局连接池对象似乎正在被清理。例如，当我调用其余端点时，我看到：

Traceback (most recent call last):
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request    
rv = self.dispatch_request()
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/myuser/sandboxes/myapp-server-logger/app.py", line 45, in log_user_data
    cursor.execute(query, (username, request.get_data()))
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/mysql/connector/cursor.py", line 463, in execute
    if self._have_unread_result():
  File "/home/myuser/virtualenv/py2.7-myapp-server-logger/lib/python2.7/site-packages/mysql/connector/cursor.py", line 288, in _have_unread_result
    return self._connection.unread_result
ReferenceError: weakly-referenced object no longer exists

我是烧瓶新手，这是存储连接池对象的不正确方式吗？

Answer 1

事实证明，问题在于数据库连接在使用游标之前被清理并返回到池中。使用游标时必须将连接保持在范围内。这似乎是 mysql.connector python 中的一个设计缺陷，并且游标应该保持对连接对象的强引用。

更改这一行：

cursor = g.cnx_pool.get_connection().cursor()

对此

conn = g.cnx_pool.get_connection()
cursor = conn.cursor()