MySQL server has gone away

[anonymous]

Whenever the MySQL server restarts we get this error:

Python Traceback

Traceback (most recent call last):
  File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 362, in dispatch_request
    env.shutdown(threading._get_ident())
  File "/usr/lib/python2.3/site-packages/trac/env.py", line 186, in shutdown
    DatabaseManager(self).shutdown(tid)
  File "/usr/lib/python2.3/site-packages/trac/db/api.py", line 75, in shutdown
    self._cnx_pool.shutdown(tid)
  File "/usr/lib/python2.3/site-packages/trac/db/pool.py", line 139, in shutdown
    self._cleanup(tid)
  File "/usr/lib/python2.3/site-packages/trac/db/pool.py", line 121, in _cleanup
    cnx.rollback()
OperationalError: (2006, 'MySQL server has gone away')

[Matthew Good]

Duplicate of #3645.

[Christian Boos]

Yes, it's a duplicate of #3645, but actually it gives also some hints about weaknesses in the pool code: here, we see that the exception occurring in line 121 in _cleanup will consume a connection for ever… and therefore this can potentially lead to #3504 (hangs).