Usually it is a good idea to set the shared value too. This works for me.

use threads;
use threads::shared;

my %shash;
my @choices;
my $x;

share $shash{'go'};
share @choices;
share $x;

$shash{'go'} = 0;
@choices = (  );
$x = 1;
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Also if you declare them as shared, after you initialize them, you will lose the initialization.

Another tip is the main thread will not automatically read the shared variable (like thru a reference). You may need to actively read it in the main thread.