### perl code example -- two threads add up the shared $total

use threads;
use threads::shared;
my $total :shared=0;
my $t1=threads->create(\&add, "t1");
my $t2=threads->create(\&add, "t2");
$t1->join();
$t2->join();
print "now the total is: $total\n";
sub add {
my $name=shift;
for(my $i=0; $i<10; $i++) {
print "$name before total=$total\n";
$total++;
print "$name after total=$total\n\n";
sleep(1);
}
}

### Output

t1 before total=0
t1 after total=1
t1 before total=2
t1 after total=3
t1 before total=4
t1 after total=5
t1 before total=6
t1 after total=7
t1 before total=8
t1 after total=9
t1 before total=10
t1 after total=11
t1 before total=12
t1 after total=13
t1 before total=14
t1 after total=15
t1 before total=16
t1 after total=17
t1 before total=18
t1 after total=19
t2 before total=1
t2 after total=2
t2 before total=3
t2 after total=4
t2 before total=5
t2 after total=6
t2 before total=7
t2 after total=8
t2 before total=9
t2 after total=10
t2 before total=11
t2 after total=12
t2 before total=13
t2 after total=14
t2 before total=15
t2 after total=16
t2 before total=17
t2 after total=18
t2 before total=19
t2 after total=20
now the total is: 20