use threads;
my @arr = (1,2,3,4);
my $outnumber=1;

print "\n variable outside thread that is in main program $outnumber\n";
my @threads;
foreach (@arr) {
   push @threads, threads->new(\&doSomething, $_, $outnumber);
}
foreach (@threads) {
   $_->join();
}

sub doSomething ()
{
  my ($thread)=@_;

  lock $outnumber;
  my $intervariable=$outnumber;
    print "\n Before increment is $intervariable\n";
    ++$intervariable;
	
	print "\n After increment is $intervariable\n";
    print "thread $thread\n";

}