This scenario can work from (cmd.exe) console (no blocking), but not under whatever environment apache sets up (something like without console )

The problem is apache -- actually most webservers -- in that they do not forward the output from CGI processes until (all copies of) both STDOUT and STDERR handles have been closed. If you close those before launching your async process via system 1, ..., then it will not cause the server to block. You can also close them (immediately) within the async script or process.

With respect to Win32::Process, if you set the iflag parameter to false:

Win32::Process::Create($obj,$appname,$cmdline,$iflags,$cflags,$curdir)

Creates a new process.
    Args:

        $obj            container for process object
        $appname        full path name of executable module
        $cmdline        command line args
        $iflags         flag: inherit calling processes handles or not
        $cflags         flags for creation (see exported vars below)
        $curdir         working dir of new process
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That will also prevent the problem.