#781: SQLObject does not reconnect
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Reporter: ghaering | Owner: anonymous
Type: defect | Status: new
Priority: normal | Milestone:
Component: SQLObject | Version: 0.9a4
Severity: critical | Resolution:
Keywords: sqlobject 'MySQL server has gone away' |
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Changes (by nEO):
* keywords: => sqlobject 'MySQL server has gone away'
Comment:
It's a realy annoying problem.
from mysql 5.0.3 the reconnect flag default is 0.
so, after mysql wait_timeout, the connection is lost.
http://dev.mysql.com/doc/refman/5.0/en/upgrading-from-4-1.html
If your app using tg.visit,tg.identity, and your app idle time > mysql
connection wait_timeout (set in my.cnf wait_timeout), Then you will lost
all mysqldb connections. and all identy required pages will return 500
server error.
It's fairly easy repeat this problem, just set mysql wait_timeout to 10
and quickstart a new project with identity. Then you will catch it.
The call trace looks like:
{{{
Exception in thread VisitManager:
Traceback (most recent call last):
File "/usr/lib64/python2.4/threading.py", line 442, in __bootstrap
self.run()
File "/usr/lib64/python2.4/site-packages/TurboGears-0.9a8-
py2.4.egg/turbogears/visit/api.py", line 256, in run
self.update_queued_visits(queue)
File "/usr/lib64/python2.4/site-packages/TurboGears-0.9a8-
py2.4.egg/turbogears/visit/sovisit.py", line 73, in update_queued_visits
conn.query( conn.sqlrepr(u) )
File "/usr/lib64/python2.4/site-packages/SQLObject-0.7.1dev_r1675-
py2.4.egg/sqlobject/dbconnection.py", line 305, in query
return self._runWithConnection(self._query, s)
File "/usr/lib64/python2.4/site-packages/SQLObject-0.7.1dev_r1675-
py2.4.egg/sqlobject/dbconnection.py", line 219, in _runWithConnection
val = meth(conn, *args)
File "/usr/lib64/python2.4/site-packages/SQLObject-0.7.1dev_r1675-
py2.4.egg/sqlobject/dbconnection.py", line 302, in _query
self._executeRetry(conn, conn.cursor(), s)
File "/usr/lib64/python2.4/site-packages/SQLObject-0.7.1dev_r1675-
py2.4.egg/sqlobject/mysql/mysqlconnection.py", line 60, in _executeRetry
return cursor.execute(query)
File "/usr/lib64/python2.4/site-packages/MySQLdb/cursors.py", line 137,
in execute
self.errorhandler(self, exc, value)
File "/usr/lib64/python2.4/site-packages/MySQLdb/connections.py", line
33, in defaulterrorhandler
raise errorclass, errorvalue
OperationalError: (2006, 'MySQL server has gone away')
}}}
So, I do a quick dirty hack on SQLObject to handle the mysql connection
timeout and mysql database restart.
I think the best solution is SQLObject do a connection check before do
raw sql query, and handle OperationalError exception, if MySQL server is
gone away then try to reconnect.
here is the sqlobject patch for who is borning with the same problem.
----
{{{
gentoo sqlobject # diff -Nura dbconnection.py.orig dbconnection.py
--- dbconnection.py.orig 2006-07-26 23:21:23.000000000 +0800
+++ dbconnection.py 2006-07-27 00:12:44.000000000 +0800
@@ -214,11 +214,27 @@
self._binaryType = type(self.module.Binary(''))
def _runWithConnection(self, meth, *args):
+ try:
+ import _mysql_exceptions
+ except ImportError:
+ MySQLdbExcept = ImportError
+ else:
+ MySQLdbExcept = _mysql_exceptions.OperationalError
+
conn = self.getConnection()
try:
val = meth(conn, *args)
- finally:
+ except MySQLdbExcept:
+ #print "make reconnection"
self.releaseConnection(conn)
+ conn = self.makeConnection()
+ self._connectionNumbers[id(conn)] = self._connectionCount
+ self._connectionCount += 1
+ try:
+ val = meth(conn, *args)
+ finally:
+ self.releaseConnection(conn)
+ #finally:
return val
def getConnection(self):
}}}
--
Ticket URL: <http://trac.turbogears.org/turbogears/ticket/781>
TurboGears <http://www.turbogears.org/>
TurboGears front-to-back web development
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