On Thu, Jan 8, 2009 at 11:08 AM, Scott Ribe <scott_r...@killerbytes.com> wrote: >> Careful! Unless you're synchronizing access to the mutable >> dictionary, this is not thread-safe. Even if it appears to work in >> some cases, it's likely to blow up in your face in real-world use. > > Right, in general, but I don't see any problem with the proposed use, since > there's adequate synchronization implicitly: > > - Main thread sets up dictionary, retains it, spawns secondary thread. > > - 2nd thread retains the dictionary, reads parameters, does its stuff, adds > results to the dictionary, releases the dictionary, calls > performSelector:onMainThread. > > - Main thread reads results, releases the dictionary.
May as well ditch the shared dictionary altogether if you're doing this. Instead follow this plan: - Main thread sets up dictionary, spawns secondary thread and passes it as an argument. - Secondary thread uses its argument to do its calculations. - When it's done, it constructs a response dictionary, calls performSelectorOnMainThread:... to hand it back. By removing shared mutable data you remove a huge potential for things to go wrong with your threads. > Note that the retain/release in the 2nd thread is really only necessary if > there's a possibility that the main thread will lose interest in the results > and release the dictionary before the 2nd thread finishes. It's actually not necessary at all. NSThread, like any other Cocoa class, knows about Cocoa memory management and will retain/release the thread object and arguments appropriately. (As will performSelectorOnMainThread:.) Mike _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
