Hi I've done some more looking at menus and how they are rendered. Recall I was investigating the performance of the IPerson/+subscribedbranches page rendered by the view PersonSubscribedBranchesView
> I think Curtis sent some mails about the menu infrastructure and how it > sucks for the way it's used now a while ago... yes, here: > > http://www.mail-archive.com/[email protected]/msg04271.html > The above link sums it up pretty well. Wish I had read it before I did my investigation - would have saved me some reverse engineering time :-) This is the exact issue I discovered happening on the page in question: * Many templates define an instance of a menu at the start of the markup to avoid the cost of duplicate instances, but we know that the menu will be reinstantiated in a portlet. Creating reusable markup often means death by menu queries Having @cachedproperty decorators on the menu object does no good because there's 2 copies of the menu object created - once at the start of the markup and once in the portlet. Another bad thing that happens is that the canonical.launchpad.webapp.MenuBase class eagerly iterates over all menu links during setup (and hence executes all required underlying database queries to construct the link) even if the links are not actually rendered. Why is this? Why aren't the links rendered lazily given there can be, and in this case is, a significant set up cost? I haven't done the analysis to quantify how widespread or significant the issue is - do any others have a gut feel for whether it's worth optimising this part of the menu infrastructure? Or is this a fairly uncommon scenario and hence the effort required to improve the implementation not worth it? I don't know the codebase well enough to answer. One option previously canvassed is to move the cache down to the underlying domain object, in this case GenericBranchCollection implementing IAllBranches. This would work, but to me it would be fixing the symptoms rather than the underlying root cause but if it works... . Another option is to split the menu object into 2, one for the main page links and another for the side portlet, each with only the relevant links defined so they only get evaluated once. This seems to be the approach taken for say the Question Edit Page - ie QuestionEditMenu, QuestionExtrasMenu etc. Or maybe even a combination of both. So I'll fix the issue one way or another but would appreciate any feedback on the questions I posed above. Thanks. _______________________________________________ Mailing list: https://launchpad.net/~launchpad-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~launchpad-dev More help : https://help.launchpad.net/ListHelp
