Not knowing what your design looks like, in my head I am picturing your worker thread (which reads / generates the images) maintaining a measure of its progress (eg a float from [0,1]) and then exposing that progress value to your main thread in which the UI runs. That is the memory I envisioned potentially being shared across 2 threads. Assuming that's the case, is it safe? Probably. Is it a good habit to get into? Probably not. There is lots of good information available on thread-safe software design and programming practices. My point was just that the feeling that you had about something not seeming right was in fact a correct hunch :) -Stefan
CC: [EMAIL PROTECTED]: [EMAIL PROTECTED]: [EMAIL PROTECTED]: Re: Question about NSThread?Date: Wed, 19 Nov 2008 16:37:18 -0500Mmm I see.... Well, right now I would say my worker thread is pretty much just reading values (size of image to generate etc)... but it's not "modifying" anything... it doesn't change any variables etc... just reads the info it needs to generate the images and ...well, generates the images... If my worker thread doesn't have to "write" in any variables/objects whatever, shared with the UI, can I assume that it's safe to leave it like it is? On 19-Nov-08, at 4:32 PM, Stefan Sinclair wrote: In a word, yes :) If you are accessing a piece of memory across threads, you should be making sure you are synchronizing any access to that memory which could occur across threads. For simple primitives (such as possibly your work progress number) just using an atomic integer would suffice. For more complicated access, you will want better protection (such as using locks around any APIs which can access your data). You're probably getting away with it now b/c your UI thread (the main thread) is only reading data (the work progress value - I'm guessing a single integer or floating point value which can be read/written in a single instruction) while the worker thread is modifying it. But it doesn't hurt to use proper thread-safe access patterns for data shared between threads even for small things like this. -Stefan> From: [EMAIL PROTECTED]> To: [email protected]> Date: Wed, 19 Nov 2008 15:57:44 -0500> Subject: Question about NSThread?> > I have an app that generates a bunch of images... the process can be > long so I wanted to start it in a separate thread so that the UI can > be responsive etc...> > basically the only thing I did was:> > [NSThread detachNewThreadSelector:@selector(doLongProcess) > toTarget:self withObject:nil];> > and I added> > NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];> > at the beginning of my doLongProcess method, and [pool release] at the > end...> Now the weird part is that... it appears to be working... the images > are created...the UI stays responsive..my status textfield gets > updated (it wasn't getting updated when the long process was not in a > separate thread)...> > Am I wrong to think that it should've been much more complex than > that? (With NSLocks and whatnot...) Maybe I should just shut up and be > happy that it work, but somehow this doesn't seem right...> > Jean-Nicolas Jolivet> [EMAIL PROTECTED]> http://www.silverscripting.com> > _______________________________________________> > Cocoa-dev mailing list ([email protected])> > 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/stefan_sinclair%40hotmail.com> > This email sent to [EMAIL PROTECTED] Proud to be a PC? Show the world. Download the “I’m a PC” Messenger themepack now. Download now. Jean-Nicolas Jolivet [EMAIL PROTECTED] http://www.silverscripting.com _________________________________________________________________ Access your email online and on the go with Windows Live Hotmail. http://windowslive.com/Explore/Hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_access_112008_______________________________________________ Cocoa-dev mailing list ([email protected]) 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 [EMAIL PROTECTED]
