Here is a typical generic wait for something or timout piece of code. In this case we wait for an exclusive file lock

my $timeout = 15; # timeout in seconds
my $delay   = 1;  # number of seconds between re-tries

open (FILE, ">$file") or die "Unable to create file '$file': $!\n";
my $count = 0;
until (flock FILE, LOCK_EX) {
    sleep $delay;
    $count += $delay;
    die "Can't lock file '$file': $!\n" if $count >= $timeout;
}
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cheers

tachyon