I am not sure what class Subscriber does but, if it uses the DAL, than you
code is problematic.
The DAL is "smart" in the sense that it keep tracks of all connection open
in certain thread and closes them all (or pools them) when the thread ends.
By using a module, you store references to those connections (which may be
closed or no, depending on the thread) in a persistent object,
subscriber_pool, thus making your code not thread safe.
Can you please explain in more detail what are you trying to accomplish?
How long should the connections be cached? What is their scope? I am sure
there is a better way. :-)
On Monday, 9 July 2012 02:32:28 UTC-5, Daniel Gonzalez wrote:
>
> Hi,
>
> I am using the following pattern to use my libraries with web2py: some of
> my utilities are creating connections to databases where I have data that I
> need to serve with web2py. This data is not modeled with web2py models. In
> order to avoid re-creating these connections with every single request (I
> have a site which is performing requests with a 1s period), I have
> discovered that the importing of modules is not cleaning the module global
> variables. So now what I am doing is creating a cache for the objects that
> I want to be persistent across requests. This is my code, in file
> subscribers.py:
>
> class SubscriberPoolCls:
> def __init__(self):
> self.subscriber_pool = { }
>
>
> def get_subscriber(self, subsriber_id, myorg):
> log.info('get_subscriber > Requested subscriber_id=%s myorg=%d' %
> (subsriber_id, myorg))
> if not subsriber_id in self.subscriber_pool:
> self.subscriber_pool[subsriber_id] = Subscriber(myorg,subsriber_id
> )
> return self.subscriber_pool[subsriber_id]
>
>
> def unsubscribe_all(self):
> for subsriber_id in self.subscriber_pool:
> self.subscriber_pool[subsriber_id].unsubscribe()
>
>
> _subscriber_pool = None
>
>
> def SubscriberPool():
> global _subscriber_pool
> if not _subscriber_pool:
> _subscriber_pool = SubscriberPoolCls()
> return _subscriber_pool
>
> And then in a request I do the following (default.py):
>
> from subscribers import SubscriberPool
>
> subscriber_pool = SubscriberPool()
>
> ...
>
> def init_session():
> if not session.my_session_id:
> session.my_session_id = get_uuid()
>
> ...
>
> @auth.requires_login()
> @service.jsonrpc
> def get_call_details(pars_json):
> init_session()
> myorg = session.auth.user.org_id
> pars = simplejson.loads(pars_json)
> subscriber = subscriber_pool.get_subscriber(session.my_session_id,myorg
> )
> activity_cdr = subscriber.get_call_details(pars['cdr_doc_id'])
> response = {
>
> 'cdr_details' : activity_cdr,
> }
> return simplejson.dumps(response)
>
> By doing this I can create a subscriber object associated to the session
> and the organization, and I get to reuse this object in subsequent requests.
>
> Now I have the following questions:
>
> 1. Why are the imported modules keeping the global variables?
> default.py is not, as far as I can tell. I would say it is reparsed with
> each request.
> 2. I have the problem that my object cache
> (SubscriberPoolCls.subscriber_pool) can grow indefinitely. I do not know
> how or when to delete entries from this cache.
> 3. Do you think this pattern is dangerous? Do you have an alternative?
>
> Thanks,
>
> Daniel
>
