When performance testing ARC code, remember to test in a release configuration, with compiler optimisations on. In my experience, it can really make a big difference; a lot of 'spurious' retain/release pairs are optimised away, and many objects are released earlier.
Jamie. On 9 Sep 2013, at 11:15, Kevin Meaney <k...@yvs.eu.com> wrote: > > On 9 Sep 2013, at 10:33, Tom Davie <tom.da...@gmail.com> wrote: >> >> Yes, it does. If you’d like an example to verify this behaviour with, play >> with converting https://github.com/beelsebob/CoreParse to ARC, and profiling >> the result. This is the example that showed 100% slowdown initially. The >> last time I tried this with with Xcode 4.5, and after I’d added a bunch of >> extra autorelease pools all over the place which reduced ARC’s overhead to >> “only" 50%. This in itself suggests to me that ARC causes a significant >> increase in the number of autoreleased objects (which surprised me given the >> runtime optimisation to get rid of autorelease/retain pairs in >> callee/caller). > > One of the things that has changed in the code that I write, is that in > manual retain/release I would often use the autorelease class methods for > creating an object arrayWith... etc. and think about the placement of > autorelease pools. Using ARC I almost never use these class methods for > creating an object but instead use alloc init. I don't have a lot of > temporary objects hanging around now. > > My new project is still so far from ready that optimizing at this point is > not sensible. I do have however a bunch of utility functions that do a lot > and currently use cocoa for doing the work but that nearly all the cocoa can > be replaced by their toll free bridged core foundation equivalents. So if > measurement proves that a lot of time is spent in these methods I'll rewrite > them then. > > Kevin > > > _______________________________________________ > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/jamie%40montgomerie.net > > This email sent to ja...@montgomerie.net _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
