**Jacob Bartlett** @jacobtechtavern [2026-05-02](https://x.com/jacobtechtavern/status/2050622398999810240)When you want to parallelize your Swift code, should you reach for an async let or a task group?
**sparrow** @sparrow824770 [2026-05-02](https://x.com/sparrow824770/status/2050664907444560056)How do you know it executes on a non-main thread? Without using an actor, or concurrent keyword. With GCD, there was no doubt. With swift concurrency you never really know.
**tk** @absolute\_\_tk [2026-05-02](https://x.com/absolute__tk/status/2050646367165645259)thanks for sharing as always!
**sparrow** @sparrow824770 [2026-05-02](https://x.com/sparrow824770/status/2050664907444560056)How do you know it executes on a non-main thread? Without using an actor, or concurrent keyword. With GCD, there was no doubt. With swift concurrency you never really know.
**tk** @absolute\_\_tk [2026-05-02](https://x.com/absolute__tk/status/2050646367165645259)thanks for sharing as always!