Hey folks, I want to warn the community about an upcoming change to pyramid_tm that has been a long time in the making. I'm excited about it - but I also don't want to blindside anyone with a large-ish backward incompatible change.
TLDR - You may want to pin 'pyramid_tm < 2.0' until you have a chance to understand the changes. There have been 3 major issues with pyramid_tm since its inception: 1) pyramid_tm doesn't cover exception view code so anything you do in an exception view should not be touching transactional objects or performing create / update / delete (non-readonly) queries. 2) Retry support has never fully torn down the request so if you're storing any transactional data in a request property (like request.user) and you have tm.attempts > 1, you may be leaking objects across transactions leading to subtle issues. 3) There is lots of room for subtle bugs when you perform changes to a transaction outside of the scope of pyramid_tm (it only covers part of the request lifecycle). The resolution of these issues has involved several steps including a new library, a new concept in pyramid and changes to the transaction library and pyramid_tm. 1) The pyramid_tm tween was moved in the tween hierarchy to be OVER the EXCVIEW tween meaning transactions are kept alive during exception views and aborted later. 2) The retry support in pyramid_tm was removed and a new library was created called pyramid_retry. This library only works with pyramid 1.9 which is unreleased. The new retry library can will create a new request object for every attempt, throwing away any transactional state stored on it, leading to cleaner retries. 3) The transaction package now supports explicit transaction managers which will error when they are used after a commit/abort. You should use one by defining a "tm.manager_hook" that returns "transaction.TransactionManager(explicit=True)". I hope this was helpful. We are still reviewing the changes to pyramid_tm and 2.0 does not have a release date but let's say that I promise it won't happen before March 15. Once that goes live you won't have any retry support, if you're relying on it (but I doubt you are because of the issues above) until pyramid 1.9 which also does not have a release date. :-) Thanks! - Michael -- You received this message because you are subscribed to the Google Groups "pylons-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to pylons-discuss+unsubscr...@googlegroups.com. To post to this group, send email to pylons-discuss@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/pylons-discuss/CAKdhhwEngaXn-%3DQZe13oKgw81_XRUJn-AN_3S_NPOipNgxsG-w%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
