如何检查MySQL连接是否在Python中打开? [英] How to check if a MySQL connection is open in Python?

问题描述

我正在使用MySQLdb( http://mysql-python.sourceforge.net/).似乎connection.open和connection.sqlstate()对我不起作用.下面是代码:

I am using MySQLdb (http://mysql-python.sourceforge.net/). It seems that connection.open and connection.sqlstate() do not work for me. Below is the code:

def open(self):
    #TODO: check the connection's status
    # self.__conn.open OR self.__conn.sqlstate()
    try:
        print "sqlstate:"+str( self.__conn.sqlstate() )
        print "open?"+str( self.__conn.open )
        return "00000" == self.__conn.sqlstate()
    except Exception as e:
        print "Exception while checking MYSQL Connection:"+str(e) 
        return False

但是当我运行"sudo service mysql stop; sleep 60; sudo service mysql start;"时做测试.输出如下.似乎下面的输出永远重复了(我最终杀死了该过程).当服务器关闭时，connection.open为1，connection.sqlstate()为00000.但是，当服务器关闭时，connection.executemany()仍会引发异常.有任何想法吗?谢谢.

But when I ran "sudo service mysql stop; sleep 60; sudo service mysql start;" to do the testing. The output is as following. It seems that the following piece of output repeated for ever (I killed the process finally). When the server is down, connection.open is 1 and connection.sqlstate() is 00000. But when server is up, connection.executemany() still throw exceptions. Any ideas? Thanks.

...
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
    2015-10-20 14:09:06 Reconnected to MYSQL.
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
    2015-10-20 14:09:06 Reconnected to MYSQL.
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
    2015-10-20 14:09:06 Reconnected to MYSQL.
    2015-10-20 14:09:06 Exception while executing statement:(2006, 'MySQL server has gone away')
    2015-10-20 14:09:06 sqlstate:00000
    2015-10-20 14:09:06 open?1
...

更新

我再次测试.输出如下.每次睡眠是10秒.输出是OK，除了connection.open为1，即使服务器关闭也是如此.但是connection.sqlstate()是正确的(HY000).

I tested again. The output is as following. each sleep is 10 seconds. The output is OK except the connection.open is 1 even when server is down. But connection.sqlstate() is right (HY000).

 2015-10-20 14:35:56 Exception while executing statement:(2006, 'MySQL server has gone away')
2015-10-20 14:35:56 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:35:56 sqlstate:HY000
2015-10-20 14:35:56 open?1
2015-10-20 14:35:56 sleeping...
2015-10-20 14:36:06 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:06 sqlstate:HY000
2015-10-20 14:36:06 open?1
2015-10-20 14:36:06 sleeping...
2015-10-20 14:36:16 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:16 sqlstate:HY000
2015-10-20 14:36:16 open?1
2015-10-20 14:36:16 sleeping...
2015-10-20 14:36:26 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:26 sqlstate:HY000
2015-10-20 14:36:26 open?1
2015-10-20 14:36:26 sleeping...
2015-10-20 14:36:36 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:36 sqlstate:HY000
2015-10-20 14:36:36 open?1
2015-10-20 14:36:36 sleeping...
2015-10-20 14:36:46 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:46 sqlstate:HY000
2015-10-20 14:36:46 open?1
2015-10-20 14:36:46 sleeping...
2015-10-20 14:36:56 Exception while ping:(2003, "Can't connect to MySQL server on '10.1.1.25' (111)")
2015-10-20 14:36:56 sqlstate:HY000
2015-10-20 14:36:56 open?1
2015-10-20 14:36:56 sleeping...
2015-10-20 14:37:06 sqlstate:00000
2015-10-20 14:37:06 open?1
2015-10-20 14:37:06 Reconnected to MYSQL.

推荐答案

一段时间以来，我一直在寻找该解决方案，但找不到合适的解决方案.

I have been searching for this solution for some time and I couldn't find an elegant solution.

似乎没有直接的方法可以做到这一点.如果尝试执行查询，您只会发现连接已关闭.

It seems there isn't a direct way of doing that. You will only find out your connection is closed if you try to execute a query.

我最终做的事情与此答案类似: 如何在python中实时检查连接?

I end up doing something similar to this answer: How to check the connection alive in python?

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