Hi there,
I am writing a little persistant Queue class/s using sqlalchemy and
sqlite. All is going fine with the development but now I have reached
the stage where I would like to have each request spawned as a new
process (from Python's muliprocessing module).
The error I am getting is: "Can't pickle <class
'sqlalchemy.orm.session.Session'>" it's not the same object as
sqlalchemy.orm.session.Session
pickle.PicklingError:
In my one class that is the closest to SQLite I have the following in
the INIT method:
def __init__(self, queueConnection):
self._queue = queueConnection.queue
self._queueName = queueConnection.queue.name
self._engine = queueConnection.engine
self._sessionmaker = sessionmaker(bind=self._engine)
self._session = self._sessionmaker()
mapper(_Message, self._queue)
And if the calling client called the "SEND" method to send a message
to the queue...the code is as follows:
def send(self, message, timeout=10, callback=None):
start_pipe, end_pipe = Pipe()
start_pipe.send(message)
p = Process(target=self._queue_proxy.send, args=
(end_pipe,)).start()
result = p.join(timeout = timeout)
if result == False:
return "Timeout"
else:
return start_pipe.recv()
The exception is raised when the following line of code runs above:
p = Process(target=self._queue_proxy.send, args=(end_pipe,)).start
()
NOTE: The "self._queue_proxy" object above is essentailly the object
that holds the reference to the "SessionMaker" above.
Does anyone have any idea how I can get around this Pickling error?
Any help will be greatly appreciated ;-)
Lynton
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