I am writing a multithreaded program (say, large number of threads just to make the problem dramatic) where I need multiple threads to change hash values of hash keys in an atomic fashion. I understand that I can use shared variables and lock etc, but is there a way to lock just one key instead of the entire hash structure? It seems odd that there is not a straight forward way to lock just the key I am operating on, but have to lock the entire structure. What am I missing here? 

our %h:shared;

sub lock {
   my ($key, $val) = @_;
     # critical section
     {
        lock($h);   # don't like this part, I want to lock($h{$key});
        $h{$key} = $val;
     }
 }

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In reply to Avoid Locking Entire Hashes by jagan_1234

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