I'm guessing the process to which you send a "negative signal" must be the head of a process group. Testing corroborates. 

$ perl test.pl 2 perl -e'system("sleep 4; echo My work is done")'
timed out
sent kill to 0
My work is done
$?=0

$ perl test.pl 2 perl -MPOSIX -e'setpgrp(0,0); system("sleep 4; echo M
+y work is done")'
timed out
sent kill to 1
$?=15

[download]

You could solve your problem by using the following: 

eval{
     local $SIG{ALRM} = sub {die "alarm\n"};
     alarm $timeout;
     $cpid = open3("<&STDIN", ">&STDOUT", ">&STDERR", '-');

     if (!$cpid) { # Child
         setpgrp(0,0);
         exec(@ARGV)
             or die "exec: $!";
     }

     waitpid($cpid, 0);
     alarm 0;
};

[download]
$ perl fixed.pl 2 perl -e'system("sleep 4; echo My work is done")'
timed out
sent kill to 1
$?=15

[download]

This code works with older version of Perl (e.g. Perl 5.10), but I'm getting an "illegal seek" error with newer version of Perl. I'll look into it. Especially since I think it might be in the code I wrote for open3 X_X.

PS — open3(...) or die $!; is wrong. open3 dies on error rather than returning false.

In reply to Re: Killing process group run with IPC::Open3 by ikegami
in thread Killing process group run with IPC::Open3 by pm_sanchay

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