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A comment on TheKitchenSync - A Tool Belt for iOS Concurrency. Parent comment

Re:TheKitchenSync - A Tool Belt for iOS Concurrency by asarazan on Tuesday May 14, 2013 @11:44AM (#5705652)
I've been thinking about this since yesterday, and it seems like a really good solution for some use cases, but isn't there quite a bit of overhead to using a dispatche queue for fine-grained operations? I mean it seems like the overhead of cross-thread communication would severely outweigh a simple synchronous lock call.

Then again, if you can do things like background non-essential operations, then the higher-level benefits can probably outweigh that.

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Re:TheKitchenSync - A Tool Belt for iOS Concurrency by mikeash on Tuesday May 14, 2013 @12:04PM (#5705810)
Like I said, GCD has a heavy emphasis on performance. For example, a dispatch_sync will involve no cross-thread communication in the uncontended case, and the cost is comparable to taking a spinlock. A bit heavier, but not too much.

dispatch_async will necessarily be slower, but don't overestimate how much work is really going to happen in the cases where it matters.

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