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libdispatch idea of using specific queues for serialized concurrency is nice, but its abstractions on top are unfortunately not as efficiently designed as it co

libdispatch idea of using specific queues for serialized concurrency is nice, but its abstractions on top are unfortunately not as efficiently designed as it could be; `dispatch_source` doesn't allow for direct completion based IO schemes (io_uring, IOCP), pushing to a `dispatch_queue` always requires a heap allocation, `dispatch_semaphore/dispatch_sync` blocks the thread instead of yielding asychronously (can cause "thread explosion"). Systems like Go don't have these constraints I don't think.

astrange 3y ago
> `dispatch_semaphore/dispatch_sync` blocks the thread instead of yielding asychronously (can cause "thread explosion") dispatch_group can do waits without blocking threads, but asynchronicity is overrated, and dispatch's design makes it easy to overdo. Having default global concurrent queues was probably a mistake. Swift concurrency is a more modern design here.