On Fri, Mar 05, 2004 at 11:16:37AM +0000, Chris Withers wrote: > Hi Marco,
Hi. > Marco Bizzarri wrote: > > >We're trying to tackle a problem in hanging connections in ZPsycopg. > > Hehe, I fixed this for ZOracleDA a couple of months ago. You may want to > look at the thread pool code in there to see how I did it, gimme a nod if > you need a URL (it's on a CVS branch in cvs.zope.org) I took a look at that, the connections.CTM, and the other. The simple question is if this is a known problem with *ALL* db adapters, and, in this case, it could be possible to devise a general solution, or if this has something to do with psycopg. I've a scenario where I can produce hanging connections in ZPsycopg: 1) use page with sql methods 2) refresh a product 3) repeat 1) 4) refresh a product if you have 4 threads, you should have now 5 connections. Obviously here there is something wrong with the management of _v_ attributes, in particular the _v_database_connection in the DA.py. The psycopg code is quite similar to the basic DA.py code, so I was looking for other ways of approaching the problem. > >However, I would like to have some information about the functioning of > >the _v_ attributes, and the cache management. In particular: > > > >1) where is the code which handles the _v_ attributes (I like to look at > >the source code, you know ;)) > > Never bothered finding it, the sematics are pretty well documented. Yes, actually. > >2) where is the code which handles the caching of the objects? > > The ZODB cache. It's big and complicated, trust me, you DON'T need to go > there... :( > >3) is it possible to disable caching of some object? > > No. The fact that you want to means you're mis-using _v_ attributes ;-) My feeling was that the hanging connection problem was related to the cache... so the question (I'm not using _v_ attributes in any particular way) > >4) when an _v_ attribute is removed, what code of the object/attribute > >itself is called? > > None. I believe it gets lost at the object is ghosted. > > >If possible, please answer also directly to me (I'm not on this list). > > Are you maintaining ZPsychopg? If not, the maintainers might be able to > help... No, actually we've a db application which makes a lot of use of zpsycopg for insert/updates, not only for select, and we stumbled on this problem. We're working with Federico Di Gregorio (psycopg mantainer) in order to solve the problem. > cheers, > > Chris - who learnt a whole lot more about ZODB and ZODB caching when > solving this kind of problem in ZOracleDA ;-) I suspect I will have to learn something in the hard way too :) > -- > Simplistix - Content Management, Zope & Python Consulting > - http://www.simplistix.co.uk Thanks for your help Regards Marco -- Marco Bizzarri - Amministratore Delegato - Icube S.r.l. Sede: Via Ridolfi 15 - 56124 Pisa (PI), Italia E-mail: [EMAIL PROTECTED] WWW: www.icube.it Tel: (+39) 050 97 02 07 Fax: (+39) 050 31 36 588
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