IIRC this doesn't work on Windows; in practice, the only useful thing you can use in a non-blocking way on that OS is a network socket. (At least, it doesn't work with straightforward, portable Perl code, you have to use a Win32 API call to achieve something comparable). (Also, this was true a few years ago on Windows 7. I haven't touched their newer products.)

If you search among my past writeups, you can find a worked GTK2 example that runs a background process and communicates bidirectionally with it.