错误：
ERROR sqlalchemy.pool.QueuePool Exception during reset or similar
2017-02-20 10:16:38,016 INFO sqlalchemy.pool.QueuePool Invalidate connection <_mysql.connection open to '127.0.0.1' at 29427b0> (reason: OperationalError:(2006, 'MySQL server has gone away'))
解决：
参考链接：https://dev.mysql.com/doc/refman/5.7/en/gone-away.html
在/usr/local/mysql/my.cnf文件里加上如下（不用重启）：
max_allowed_packet = 16M
wait_timeout=2880000
interactive_timeout = 2880000
done!
