4.2 Thread::Semaphore

Thread::Semaphore

Semaphores provide a mechanism to regulate access to resources.

use Thread::Semaphore;
my $s = new Thread::Semaphore;

$s->up;
# The guarded section is here
$s->down;

Semaphores don't limit their values to zero or one, so they can be used to control access to some resource that there may be more than one of.

my $s = new Thread::Semaphore(6);  # default is 1
$s->up(2);
$s->down(1);
$s->down(1);