To add a slight bit to this: ActivePerl 5.6.0 has thread support in the form of a fork which actually creates threads. This is new code and still pretty buggy. If you compile your own copy of Perl to use another threading model then you won't be able to use fork() with that version of Perl (for Win32).

The demand for a pseudo-fork() was part of the reason ActiveState decided to not support 5.005-style threads in 5.6.0. Another part of the reason is probably that the future of threads in Perl5 (if there is any at all now that Perl6 is in the works) could go several directions and there didn't seem to be a strong consensus on which way to choose so 5.005-style threads might not see much more development.

Although the 5.005-style threading support was still buggy, you might have better luck with it than with the current pseudo-fork().

        - tye (but my friends call me "Tye")