Hi, I have investigated this issue further and found out that it is present also in the latest perl5 blead. Based on Vicent's post above I have tried this patch to win32/perlhost.h - PerlInterpreter *new_perl = perl_clone_using((PerlInterpreter*)aTHX, 1, + PerlInterpreter *new_perl = perl_clone_using((PerlInterpreter*)aTHX, 1 | CLONEf_KEEP_PTR_TABLE, and IT SOLVES the described fork issue but I am not able to say that this is the right way for fixing it. I would appreciate any feedback. -- kmx