There are several ways of achieving your goal. I cannot infer which is appropriate from your sample code.

Here are two ways:

#! perl -sw
use strict;
use threads;
use threads::shared;
use Data::Dumper;

my %hash1 :shared;
my %hash2 :shared;

while(1) {
    async( \&sub1)->detach;
    async( \&sub2)->detach;

    sleep(2);
    lock %hash1; lock %hash2;
    print '$hash1'. Dumper(\%hash1) ."\n";
    print '$hash2'. Dumper(\%hash2) ."\n";
    print "_______________________________\n";
}

sub sub1
{
        my $now = scalar localtime;
        lock %hash1;
        $hash1{'time'} = $now;
}


sub sub2
{
        my $now = scalar localtime;
        lock %hash2;
        $hash2{'time'} = $now;
}
[download]

#! perl -sw
use strict;
use threads;
use Data::Dumper;

my %hash1;
my %hash2;

while(1) {
    my( $t1 ) = threads->create( \&sub1 );
    my( $t2 ) = threads->create( \&sub2 );

    sleep(2);
    %hash1 = $t1->join;
    %hash2 = $t2->join;
    print '$hash1'. Dumper(\%hash1) ."\n";
    print '$hash2'. Dumper(\%hash2) ."\n";
    print "_______________________________\n";
}

sub sub1
{
        my $now = scalar localtime;
        return time => $now;
}


sub sub2
{
        my $now = scalar localtime;
        return time => $now;
}
[download]

Try them, note the differences, and ask questions.