Re: Question about NSThread?
Re: Question about NSThread?
- Subject: Re: Question about NSThread?
- From: Jean-Nicolas Jolivet <email@hidden>
- Date: Wed, 19 Nov 2008 16:37:18 -0500
Mmm 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@hidden
> To: email@hidden
> 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@hidden
> http://www.silverscripting.com
>
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