In a recent thread about starting detached processes on Windows using the special form system(1,...), I got a recommendation to use Win32::Job instead of system(1,...), as this would be safer to use and easy too. So I started to play around with Win32::Job, basically trying this:

... 
my $j=Win32::Job->new;
$j->spawn('perl.exe', "perl.exe myprog.pl", {
       new_console=>0,
       new_group=>1,
       stderr=> $out,
       stdout=> $out
  })
unlink 'killfile.txt';
$j->watch(sub { -e 'killfile.txt' ? 1 : 0 }, 3);
print "go on\n";
...
[download]

The purpose of watch() is to abort the spawned program and all child processes it might have been created, prematurely if the file killfile.txt gets created.

This works indeed, but there is one big difference compared to when I implement the same using system(1,...):

With system(1,...), I get a separate process, i.e. my Perl program continues to run. With Win32::Job, the watch call blocks, i.e. "go on" is printed only after "perl.exe myprog.pl" has (forcefully or gracefully) finished; so Win32::Job doesn't seem to be an alternative for system(1,...), but simply something different.

Of course I could combine the two approaches: Write a helper script 'spawn_and_watch.pl', which I would start with system(1,...), and which does the spawn and watch calls; but I have somehow the feeling that there should be an easier solution. Did I miss something here?

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