I think its neccessary behavior. If the shared variable declaration is inside a scoped sub, how can the main:: thread keep it shared in it's global scope? As soon as the sub finishes, the shared var is out of scope. I always have seen shared vars declared in the global section of main::.

You might be confusing the behavior of shared with our?

Look at this code where our is used instead of my. It works.

#!/usr/bin/perl
use warnings;
use strict;

use threads;
use threads::shared;
use Data::Dumper;

sub test {

#     my %h ; shared;  #dosn't work
       our %h : shared;   #works

    for (1 .. 3) {
        threads->create(sub {
                            my $n = shift;
                            lock %h;
                            $h{$n} = rand;
                        }, $_)->join;
    }
    return %h;
}

print Dumper {test()};
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