Twisted adbapi errors and log.err

Question

I'm debugging the 'MySQL server has gone away' errors. There is a proposed solution, which more or less works:

from twisted.enterprise import adbapi
from twisted.python import log
import MySQLdb

class ReconnectingConnectionPool(adbapi.ConnectionPool):
    """Reconnecting adbapi connection pool for MySQL.

    This class improves on the solution posted at
    http://www.gelens.org/2008/09/12/reinitializing-twisted-connectionpool/
    by checking exceptions by error code and only disconnecting the current
    connection instead of all of them.

    Also see:
    http://twistedmatrix.com/pipermail/twisted-python/2009-July/020007.html

    """
    def _runInteraction(self, interaction, *args, **kw):
        try:
            return adbapi.ConnectionPool._runInteraction(self, interaction, *args, **kw)
        except MySQLdb.OperationalError, e:
            if e[0] not in (2006, 2013):
                raise
            log.msg("RCP: got error %s, retrying operation" %(e))
            conn = self.connections.get(self.threadID())
            self.disconnect(conn)
            # try the interaction again
            return adbapi.ConnectionPool._runInteraction(self, interaction, *args, **kw)

Taken from here: http://www.gelens.org/2009/09/13/twisted-connectionpool-revisited/

However, the exception gets caught no only in our ReconnectingConnectionPool, but in _runInteraction itself too. And it triggers log.err, which (apparently) does two things:

• print the error - although our application works fine
• what's worse, it makes trial fail, so the tests fail. I'm not really sure this is log.err problem, but it happens nonetheless.

I could hack adbapi, but that's probably not the best idea. Are there any better ways to handle this?

Answer 1

Are you asking how to make a unit test pass even if an error is logged? Try flushLoggedErrors. If you're asking something else, please clarify.