MySQL server has gone away error handling

Solution 1:

This is a mechanism of MySQL itself:
MySQL automatically disconnects the connection after more than 8 hours of idle time
There are two solutions:
1. Modify MySQL Configuration
Increase the value of the MySQL Wait_timeout property
2, regular access to MySQL, to maintain the idle time of MySQL connection
In the application, write a timed task to access the MySQL database regularly

The above describes the "Django database re-connect mechanism" of the problem answer, I hope to have the need to help users.
This article site link: http://www.codes51.com/itwd/2831093.html

Problem description

When using Django+celery, run a long task, start the database one time, and then operate the database again after 20 hours.

After more than more than 20 hours, again operation database times wrong.

Raised Unexpected:operationalerror (2006,' MySQL server has gone away ') Traceback (the most recent callLast): File"/usr/local/lib/python2.7/dist-packages/django/db/models/manager.py",Line85,In Manager_methodReturn GetAttr (Self.get_queryset (), name) (*args, **kwargs) File"/usr/local/lib/python2.7/dist-packages/django/db/models/query.py",Line374,InchGetnum =Len (clone) File"/usr/local/lib/python2.7/dist-packages/django/db/models/query.py",Line232,In __len__ self._fetch_all () File"/usr/local/lib/python2.7/dist-packages/django/db/models/query.py",line 1118, in _fetch_all self. _result_cache = List (Self. _iterable_class (self)) File  "/usr/local/lib/python2.7/dist-packages/django/db/models/ query.py ", line 53, in __iter__ Results = Compiler.execute_sql (chunked_fetch=self.chunked_fetch) File  "/usr/local/lib/ python2.7/dist-packages/django/db/models/sql/compiler.py ", line 894, in Execute_sql raise Original_exceptionoperationalerror : (2006,  ' MySQL server has gone away ')    

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Reason connection timed out

That's why I'm having problems.
Go to MySQL and execute the following command:

Mysql> Show global variables like'%timeout '; +----------------------------+----------+|variable_name |Value |+----------------------------+----------+| Connect_timeout |10 | | delayed_insert_timeout | 300 | | innodb_lock_wait_timeout | 50 | | innodb_rollback_on_timeout | off | | interactive_timeout | 28800 | | lock_wait_timeout | 31536000 | | net_read_timeout | 30 | | net_write_timeout | 60 | | slave_net_timeout | 3600 | | wait_timeout | 28800 |+----------------------------+----------+       

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Wait_timeout is 28,800 seconds, that is, the MySQL link is automatically closed after 28,800 seconds of no operation

Workaround takes effect immediately

Execute the following SQL command

set global wait_timeout=60*60*30;

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The command is to set Wait_timeout to 30 hours.
In this way, the modification takes effect immediately. If you restart MySQL, restore the original 28,800 seconds.

Permanent effect

After this method has been modified, you need to restart MySQL to take effect.
Edit the MySQL configuration file my.cnf, add or modify this command as follows.
(my MySQL config file path:/etc/mysql/my.cnf)

wait_timeout = 108000

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Other reasons

There are other reasons to simply describe
1:mysql Service shutdown
2: Packet size is too large
Workaround: Modify max_allowed_packet the values as in the same way.

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MySQL server has gone away error handling