my %children;

sub forker1 {
   my $resource = ...;
   my $pid = ...;
   $children{$pid} = sub {
      print "forker1 child $pid exited with \$?=$?\n";
      ... clean up $resource ...
   };
}

sub forker2 {
   my $resource = ...;
   my $pid = ...;
   $children{$pid} = sub {
      print "forker2 child $pid exited with \$?=$?\n";
      ... clean up $resource ...
   };
}

...

forker1() for 1..3;
forker2() for 1..3;

while (keys(%children)) {
   my $pid = wait();
   my $handler = delete($children{$pid});
   $handler->() if $handler;
}