use strict;
use warnings;
use threads;
use feature 'say' ;
use Fcntl qw(:flock);
my $file_path = ">>/tmp/test.txt";
open(FILE, $file_path);

for(0..9) {
    threads->new(\&worker, $_);
}

$_->join for threads->list;

sub worker {
    my $x = shift;
    my $locked;
    open(my $thread_lock,$file_path);
    $locked = flock($thread_lock, LOCK_EX|LOCK_NB );
    if( $locked ) {
        say "$x: lock acquired";
        sleep 9-$x;
    } else {
        say "$x: cannot acquire lock";
    };

    if($locked) {
        flock( $thread_lock, LOCK_UN );
        print "$x: lock released\n";
    }
    return;
}