#!/usr/bin/perl 
use utf8;
use feature qw( say );
use threads;
use threads::shared;
use Data::Dumper;
use Storable qw ( freeze thaw );

my $LockVar :shared;
$LockVar = "default";
my $LockArray :shared;

$Lock3Sec = threads->new(
	{'void' => 'void'},
	sub {
		{
			say "the lock var default value is {$LockVar}";
			lock($LockVar) or warn "cannot lock the var because {$!}\n";
			sleep 3;
			say $LockVar;
		}
	},
);

$Lock3Sec->detach();

$TryToReadLockVar = threads->new(
	{'void' => 'void'},
	sub {
		my $count = 1;
		while( $LockVar eq 'default'){
			say "try to modify the Lock var {$count} time";
			$count += 1;
			$LockVar = 'this lock var has been change' or redo;
		}
	},
);

$TryToReadLockVar->join();


##</code><code>##

the lock var default value is {default}
try to modify the Lock var {1} time