数据库断开连接mysql has gone away

在使用python2.7+django1.8时，Mysql报错 “mysql has gone away”，查看了其他博客后得知是因为连接超时，而且都有下面这种方法，少有人提到效率的问题，而效率是不得不考虑的事情(我们写操作比较多 mysql连接 平时都是没有问题的 但是一到周末就GG)，所以亲自测一下

from django.db.backends.base.base import BaseDatabaseWrapper
import time


def close_old_connections():
    for conn in connections.all():
        conn.close_if_unusable_or_obsolete()


def close_if_unusable_or_obsolete(self):
    """
    Closes the current connection if unrecoverable errors have occurred,
    or if it outlived its maximum age.
    """
    if self.connection is not None:
        # If the application didn't restore the original autocommit setting,
        # don't take chances, drop the connection.
        if self.get_autocommit() != self.settings_dict['AUTOCOMMIT']:
            LOG.warning('mysql connect close !!!!!')
            self.close()
            return
        else:
            LOG.warning('mysql has ckeck but do nothing !!!!!')


        # If an exception other than DataError or IntegrityError occurred
        # since the last commit / rollback, check if the connection works.
        if self.errors_occurred:
            if self.is_usable():
                self.errors_occurred = False
            else:
                self.close()
                return

        if self.close_at is not None and time.time() >= self.close_at:
            self.close()
            return

BaseDatabaseWrapper.close_if_unusable_or_obsolete = close_if_unusable_or_obsolete

经过加上日志信息后发现，如果连接是正常的不会做任何事情，如果连接是无效的，会关闭旧连接，新建一个，对效率的影响不是很大，可以直接在经常报错的地方前面添加。