完整报错

运行的好好的，突然某个时间开始，使用django的model读取数据库时就会报错：

Traceback (most recent call last):File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _executereturn self.cursor.execute(sql, params)│ ││ │ └ ()│ ││ └ 'SELECT `device_discover_deviceinfomodel`.`index` FROM `device_discover_deviceinfomodel`'│ │└ <function CursorWrapper.execute at 0x7f0bafd01bf8>│ └ <django.db.backends.mysql.base.CursorWrapper object at 0x7f0a16d53eb8>└ <django.db.backends.utils.CursorDebugWrapper object at 0x7f0ba15754e0>File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 73, in executereturn self.cursor.execute(query, args)│ ││ │└ ()│ ││ └ 'SELECT `device_discover_deviceinfomodel`.`index` FROM `device_discover_deviceinfomodel`'│ │└ <function Cursor.execute at 0x7f0bb14da048>│ └ <pymysql.cursors.Cursor object at 0x7f0ba13b9780>└ <django.db.backends.mysql.base.CursorWrapper object at 0x7f0a16d53eb8>File "/usr/local/lib/python3.6/site-packages/pymysql/cursors.py", line 148, in executeresult = self._query(query)│ │└ 'SELECT `device_discover_deviceinfomodel`.`index` FROM `device_discover_deviceinfomodel`'│ └ <function Cursor._query at 0x7f0bb14da488>└ <pymysql.cursors.Cursor object at 0x7f0ba13b9780>File "/usr/local/lib/python3.6/site-packages/pymysql/cursors.py", line 310, in _queryconn.query(q)│ │└ 'SELECT `device_discover_deviceinfomodel`.`index` FROM `device_discover_deviceinfomodel`'│ └ <function Connection.query at 0x7f0bb1506268>└ <pymysql.connections.Connection object at 0x7f0a1c061cf8>File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 547, in queryself._execute_command(_QUERY, sql)│ ││ │└ b'SELECT `device_discover_deviceinfomodel`.`index` FROM `device_discover_deviceinfomodel`'│ ││ └ 3│ │└ <module 'MAND' from '/usr/local/lib/python3.6/site-packages/pymysql/constants/COMMAND.py'>│ └ <function Connection._execute_command at 0x7f0bb1506950>└ <pymysql.connections.Connection object at 0x7f0a1c061cf8>File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 793, in _execute_commandraise err.InterfaceError(0, "")│ └ <class 'pymysql.err.InterfaceError'>└ <module 'pymysql.err' from '/usr/local/lib/python3.6/site-packages/pymysql/err.py'>pymysql.err.InterfaceError: (0, '')

这行代码之前没有问题，但是突然某个时间点开始就疯狂出错

解决方案

在使用model前，使用：

import django.dbdjango.db.close_old_connections()

比如：

import django.dbdjango.db.close_old_connections()print(list(django.contrib.auth.models.User.objects.all()))

问题解析

这是因为长时间没有使用连接池里的连接，导致一部分连接已经失效，因此手动清理一下老旧的连接即可