I have found the solution myself. It's actually straightforward, set project min platform to 10.15 and I can do this without warnings anymore: Task { bagLock.lock() hashBag["file"] = hash bagLock.unlock() } Actor is too heavy for this scenario because I have several variables like this in an async function; Mutex is quite new and my project has to target a much older platform like 10.15 which enables me to use Task async.

With 16.4RC, GatherProvisioningInputs only takes 0.1 seconds. But VeryModule of the MyFramework still takes more than 16 seconds for a clean/build. BTW, my system is M1 Mac mini.

Same issue here. That's ridiculous...