What about declaring the variable shared before assigning it to your hash, as in my $var : shared = 1; $self->{var} = \$var. Although on further consideration I wonder if it might be better to be using a package variable via our or use vars since it looks like what you want is a 'static' variable i.e., one shared by all instances of a class, and these constructs provide that behavior. I don't have threads compiled so I can't test this, but this might work:

package OOThread;
use threads;
our static_var : shared = 1; # may not be necessary to explicitly shar
+e 'our' variables
sub new {...} 
...
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About that...

I absolutely, positively and lifethreateningly do NOT want to share a variable between all instances of the class.

I want to share the variable between two threads, both running in the same object.

Sharing between threads, not between objects. Vewy vewy impowtant. =) By default threads will get their own copy of all the data (a la fork) except for those vars that are " : shared". =)