Earlier quoted context omitted.
Do you think ARC is a viable alternative? I'm uncertain how the performance compares to GC for most applications.
Totally! Or RAII, but that requires much more re-thinking of how your program is put together to do it well. Performance depends on a lot of things. For instance, if you have 'unlimited' memory, GC will be way faster because most likely the collector will never run, and allocations are extremely fast since you can just hack off a slice and hand it out. But in that world, relying on something like a finalizer is impos…
With ARC sharing objects across threads becomes trickier. First of
all, in the general case you'll have to do atomic increments and
decrements which tend to be fairly expensive, and they'll be sitting
right in the middle your core application logic. Secondly, if you're
sharing objects amongst threads, you cannot simply do:
Thread1:
Obj = Heap->field;
Heap->field = null;
// reduced a reference so:
if (AtomicDecrement(Obj->refcount) == 0) {
free(Obj);
}
Thread2:
Obj = Heap->field;
// stalls, and Thread1 deletes Obj
AtomicIncrement(Obj->refcount)