You could simplify this by using a module that already tackles this problem: Parallel::ForkManager.

Here is a snippet of code that uses it to have child processes update a hash in the parent:

#!/usr/bin/perl -w
use Net::FTP;
use Parallel::ForkManager;
use strict;

my %srvs = ();
my $pm = new Parallel::ForkManager(10);
$pm->run_on_start( sub { print STDERR "Connecting to $_[1], port $srvs
+{$_[1]}{port}\n"; } );
$pm->run_on_finish
( sub {
    my (undef, $exit_code, $ident) = @_;
    if    ( $exit_code == 0 ) { $srvs{$ident}{stat} = "Good logon to $
+ident\n"; }
    elsif ( $exit_code == 1 ) { $srvs{$ident}{stat} = "*** Logon to $i
+dent failed\n"; }
    elsif ( $exit_code == 2 ) { $srvs{$ident}{stat} = "*** Connect to 
+$ident failed\n"; }
    else { $srvs{$ident}{stat} = " Script error while connecting to $i
+dent\n"; }
    print STDERR $srvs{$ident}{stat};
}  );
sub ftpcheck {
    my $id = shift;
    my $srv=$srvs{$id};
    my $status = 1;
    my $ftp=Net::FTP->new($$srv{addr},Timeout=>15,Port=>$$srv{port});
    exit(2) if ! $ftp;
    $status = 0 if $ftp->login($$srv{user},$$srv{pass});    # Change s
+tatus to 'good' if logon works
    $ftp->quit();
    exit ($status);
}
# do stuff to set up %srvs as hash of FTP servers and associated infor
+mation here

# when %srvs is setup, iterate through the keys like so:
for my $child ( keys %srvs ) {
    my $pid = $pm->start($child) and next;
    &ftpcheck($child);
    $pm->finish($child);
}
$pm->wait_all_children;

# Quick mail hack. I was in a hurry
open MAILFILE, "| mail -s 'ftpcheck results' $notify";
print MAILFILE $srvs{$_}{stat} for sort keys %srvs;
close MAILFILE;
[download]

But the obvious limitation here is that a child has to exit before the parent can be updated.