G'day micmac,

If you add use warnings;, you'll see that the exec is not being run at all:

$ pm_child_execs.pl
in test2
Can't exec "1": No such file or directory at ./pm_child_execs.pl line 
+13.
in test1
Can't exec "1": No such file or directory at ./pm_child_execs.pl line 
+13.
in test2
Can't exec "1": No such file or directory at ./pm_child_execs.pl line 
+13.
[download]

What's actually happening is that $cmd->() is being run then exec is trying to use the return value ("1" from say) as its argument.

So, the first child runs test1() then, because there's no exec, it runs test2() on the second iteration. The second child runs test2() (also with no exec). That's test1() once and test2() twice.

Changing

       exec $cmd->();
[download]

to

       #exec $cmd->();
       $cmd->();
       last;
[download]

you'll get the desired output:

$ pm_child_execs.pl
in test2
in test1
[download]

I'll leave you to decide if that's also the desired functionality.