=head1 PORTABLE PERL CODE

In portable Perl code, kill(9, $child) must not be used on forked processes.

Forked process are in Windows implemented as a pseudo-processes. 
To use kill(9, $child) on pseudo-processes is unsafe.
The process which implements the pseudo-processes can be blocked and the Perl interpreter hangs.

The outcome of kill on a pseudo-process is unpredictable.
It depends on the timing in the Windows operating system.
Code that has worked, suddenly can fail, resulting in errors which are difficult to find.