It'd be harder to control perceived performance of user facing applications though. If I can set the timeout, I can guarantee that something happens within X seconds, instead of within X iterations which could have different performance machine to machine.

is this not the halting problem? You can guarantee a certain depth isnt reached but you cant guarantee a recursion will unwind or anything like that

No, because we’re not trying to find out if the computation will ever halt with unbounded time. It just determines if it will halt after a certain number of steps, which you can always determine by executing that number of steps and bailing out.

It's not the halting problem; it's bounding computational depth

Their suggestion is essentially making stack overflow a feature in regex, & then allowing that stack depth to be tuned

Wooosh