Is @concurrent now the standard tool for shifting expensive synchronous work off the main actor?

[John_McCall]

@younata

As an example, if the system determines that the correct number of threads to use is 2, then once a long running task that doesn't even yield gets scheduled, every other task will run on the first (main) thread. If a second non-yielding long task gets scheduled, then even if it's annotated @concurrent, it'll still run on the main thread. On iOS and similar platforms, this hang can cause the system to kill your app due to being unresponsive.

This is not true; Swift concurrency does not schedule other work onto the main thread just because it’s currently available. If you have a long-running operation that’s blocking the main thread, it’s because you ran it there.