The Synchronization Framework in Swift 6

Performance testing the new concurrency primitives

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Swift 6 and iOS 18 introduced the Synchronization framework, to surprisingly little fanfare. Seriously, barely even a shout-out at dub-dub. I have my work cut out for me.

Synchronization contains two low-level concurrency primitives — Mutex and Atomics.

These features could only be introduced with Swift 6 because they are implemented using the brand-new generic ownership mechanics.

Today, we’ll understand why atomics and mutexes are useful, and learn how to use them in your own code.

Finally, we’ll profile these primitives to understand their performance compared to the high-level synchronization mechanism in Swift Concurrency: Actors.