I tried to test this, and on my machine shared version appears to take more working memory 
#!/usr/bin/perl --
use threads;
use threads::shared;

my $foo = 0 x ( 100 * 1024 );
share($foo);

threads->create(sub { $foo.= 1 x ( 100 * 1024); })->join();

sleep 10;

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In reply to Re^2: What is a shared variable? by Anonymous Monk
in thread What is a shared variable? by llancet

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