Re: async NSOperation and NSOperationQueue

[Jason Coco]

On Sep 15, 2008, at 11:02 , John Love wrote:

I must be doing something terribly wrong, because when I start up the NSOperationQueue that does some time consuming calculations, I do not get back control of my application until after the lengthy calculation is complete. Here are the relevant code snippets:

- (void) calculateWorksheetRow:(id)data {
    // takes a long time here
}

- (void) startQueue {
        theQueue = [[[NSOperationQueue alloc] init] autorelease];
        theOp = [[NSInvocationOperation alloc] initWithTarget:self

                                               object:nil];
        [theQueue addOperation:theOp];
}

selector:@selector(calculateWorksheetRow:)

pretty much have just one queue that you add NSOperation objects to. You

app controller or some other relevant place.


run and you don't want to ever add any more.

You /should/, however, autorelease your NSOperation since your queue
will retain it when you add it and release it when it completes.

Couple of things... you don't wanna create a queue every time. You should probably want to re-write this to be a singleton object that you get from your Also, you most definitely do not want to autorelease your queue. It will end up going away on you when you least want it to or expect it to. Create your queue somewhere (hopefully in your app controller or somewhere like that) and then release it when you're absolutely sure that all your operations have

- (void) stopQueue {
        [theQueue cancelAllOperations];
        
    // [theQueue release];   // [ ... autorelease]
        [theOp release];
}

all the others will have been leaked.

You should probably autorelease your Op (unless you want to query it in the future after it completes, in which case you should release it when you're finished with it). This case will also only release the last operation from your loop and

- (void) startCalculation {             
        int row;
        
        for (row=1; row < 100; row++) {
             // stuff here
                [self startQueue];   // start new thread
             // [theQueue waitUntilAllOperationsAreFinished];
        }
        
        // more stuff
}

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