Question

use threads;
use threads::shared;

sub test {
    my $s :shared = 22;
    my $thread = threads->new(\&thrsub);

    $thread->join();
    print $s;

}

sub thrsub {
    $s = 33;
}

test;

Why isn’t the data being shared in the thread?

Answer 1

It shares the variable, but you’re accessing a different variable than the one you shared. (use strict; would have told you there were different variables in this case. Always use use strict; use warnings;) The fix is to use a single variable.

my $s :shared = 22;

sub test {
    my $thread = threads->new(\&thrsub);
    $thread->join();
    print $s;
}

sub thrsub {
    $s = 33;
}

test;