iPhone: NSOperationQueue running operations serially

Question

I have a singleton NSOperationQueue that handles all of my network requests. I'm noticing, however, that when I have one particularly long operation running (this particular operation takes at least 25 seconds), my other operations don't run until it completes.

maxConcurrentOperationCount is set to NSOperationQueueDefaultMaxConcurrentOperationCount, so I don't believe that's the issue.

Any reason why this would be happening? Besides spawning multiple NSOperationQueues (a solution that I'm not sure would work, nor am I sure it's a good idea), what's the best way to fix this problem?

Thanks.

Answer 1

According to the NSOperationQueue class referenceNSOperationQueueDefaultMaxConcurrentOperationCount means that "the default maximum number of operations is determined dynamically by the NSOperationQueue object based on current system conditions." I don't see anything that says the default will be > 1 (especially on a single-CPU system).

Try calling -setMaxConcurrentOperationCount: to explicitly set a larger value, and see if that helps.