Dear All
I'm having a very strange issue with Sessions that I'm hoping someone can
guide me on;
I have a situation where a large body of code spawns new processes
(multiprocessing.process). The core design manages 3 (possible) database
connections, and I've used a unique session for each. The session is create
thus within the new process (i.e. not handed in)
Session = sessionmaker() # This is global
class myManager(object):
# I use a manager class to manage the engines, MetaData and Sessions of
the 3 possible DB's I create new sessions in here like this
self.session1 = Session(bind = engine1)
self.session2 = Session(bind = engine2)
self.session3 = Session(bind = engine3)
All this works fine and all testing up to this point has been perfect. Now,
when I start to load test and create more than one concurrent process, I'm
getting some form of corruption of my connections to the Database
(mysql+mysqlconnector) !?
All NON session based access to the server still work, but after I start the
second process, BOTH processes lost the ability to use the sessions create
(ones that where running and working stop immediately the second process
starts) with this;
(InterfaceError) 2055: Lost connection to MySQL server at '192.168.50.2:3306',
system error: 10054 u'SELECT products......
The connection is NOT lost really, as I can still do NON session based
queries using the same engine that the session is bound to.
As far as I can see, since the code is running in a completely different
process, how can they be interacting with each other and breaking the
connection to mySQL?
I've tried using scoped_session but could not work out how to have the 3
sessions as above all in the same context - so gave up. As far as I can
see though on my limited understanding of the Session process, I have
isolated everything so there should be no issues.
Any ideas?
Cheers
Warwick
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