直接用mysql命令可以正常访问数据库，但用tornado就不行，详细错误如下：
[E 150422 15:27:21 torndb:103] Cannot connect to MySQL on localhost:3306
Traceback (most recent call last):
File "build/bdist.linux-x86_64/egg/torndb.py", line 100, in init
self.reconnect()
File "build/bdist.linux-x86_64/egg/torndb.py", line 117, in reconnect
self._db = MySQLdb.connect(**self._db_args)
File "/usr/lib64/python2.6/site-packages/MySQLdb/__init__.py", line 81, in Connect
return Connection(*args, **kwargs)
File "/usr/lib64/python2.6/site-packages/MySQLdb/connections.py", line 187, in __init__
super(Connection, self).__init__(*args, **kwargs2)
OperationalError: (2002, "Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)")
找到原因了
mysql配置文件里写的是socket = /tmp/mysql.sock
改成socket = /var/lib/mysql/mysql.sock
然后重启mysql服务就好了