howdy!

I observe this strange behaviour with threads::shared (version 1.32, on Ubuntu's Perl 5.12.4 x86_64-linux-gnu-thread-multi):

use strict;
use warnings;

use threads qw(yield);
use threads::shared;
use Data::Dumper;

sub test { 
    my %h : shared; 
    for (1..3) { 
        threads->new(sub { 
            my($n) = @_;
            lock(%h); 
            $h{$n} = rand(); 
            threads->yield(); 
        }, $_)->join();
    } 
    return %h;
} 

my %k = test(); 
print Dumper(\%k);
[download]

outside of the sub I get the hash keys, but not the values. like they went out of scope, or something. the output is:

$VAR1 = {
          '1' => undef,
          '3' => undef,
          '2' => undef
        };
[download]

this happens only if I declare the shared hash in a sub and return its content. if I move the hash declaration outside of the sub, everything works:

use strict;
use warnings;

use threads qw(yield);
use threads::shared;
use Data::Dumper;

my %h : shared; 

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

my %k = test(); 
print Dumper(\%k);

# output
$VAR1 = {
          '1' => '0.608570207216875',
          '3' => '0.0436435554447634',
          '2' => '0.220397240555943'
        };
[download]

also if I return a reference to the shared hash, everything works:

use strict;
use warnings;

use threads qw(yield);
use threads::shared;
use Data::Dumper;

sub test { 
    my %h : shared; 
    for (1..3) { 
        threads->new(sub { 
            my($n) = @_;
            lock(%h); 
            $h{$n} = rand(); 
            threads->yield(); 
        }, $_)->join();
    } 
    return \%h;
} 

my $k = test(); 
print Dumper($k);

# output
$VAR1 = {
          '1' => '0.653087966217758',
          '3' => '0.0419468023619665',
          '2' => '0.199076903824793'
        };
[download]

the same exact thing happens with arrays too.

is this a bug, or the intended behaviour? and if so, why?

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