I am contemplating using threads (ithreads) in a module eventually destined for CPAN. Are there any resources I could look at to see which system perls currently compile with useithreads=define by default?

Asyncronicity is central to my module’s purpose. I’ll be able to implement a non-threaded fallback, but thanks to a lot of blocking IO and other long running functions, the user experience will be worse without threads. I can iron out most of that, at the cost of significantly complicated code. Threads are a natural fit.

Therefore the reason I ask, is simply to help me move the needle between “worse user experience” and “more complicated code”, or just “sorry, this requires threading support”.