What's wrong with GCD?

pavlov · on Dec 10, 2020

It's a great library for a lot of things. When originally introduced it was also heavily oversold by Apple as a magic bullet for concurrency.

Here's one account: https://tclementdev.com/posts/what_went_wrong_with_the_libdi...

astrange · on Dec 10, 2020

This page overstates the issues. Almost all the initial GCD design is still good, we just ended up with a lot more smaller low-core and non-SMP processors than expected.

Also most of the performance issues are with excess parallelism (runnable threads), not concurrency (hiding IO latencies).