#!/usr/bin/perl

use strict;
use warnings;
use Time::HiRes qw|time sleep|;
use Fcntl qw|:flock|;

mkdir "tmp" or warn $!;
chdir "tmp" or die $!;

for (1 .. 500){
    my $pid = fork();
    defined($pid) or die "fork failed: $!";
    if ($pid == 0) { 
        child_process();
        exit;
    }
}   
print "DONE FORKING\n";
while (wait() > -1) {}

sub child_process{
    while (1){
        while (my $file = glob "*.tmp"){
            open my $FH, '>', $file or next; #next if unlinked already
            if (flock($FH, LOCK_EX | LOCK_NB)){
                next unless flock($FH, LOCK_EX | LOCK_NB);
                print time(), " YES! I ($$) got a lock on $file!\n";
                sleep(.1); 
                unlink $file;
            }
            close $FH;
        }
        sleep(.1);
    }
}