If you're looking for the problems of tacking on threads afterwards, you can also take a look at the Python Global Interpreter Lock (and the discussion around it). While I'm not a fan of Guido van Rossum's striving for speed for speeds sake, the discussion highlights the problems that you encounter when you don't plan for share-everything threading/lightweight threading/fibers/coroutines from the start.

Of course, there remain the semantical problems of the global name space of Perl, especially what happens in a share-everything model with the following code:

sub quote_string {
    qq{"\Q$_[0]\E"}
};

sub send_to_client {
    my $client_socket = shift;
    async {
        print {$client_socket} quote_string($_) for @_;
    };
};

function send_strings_to_client {
    local *quote_string = sub {
        qq{'\Q$_[0]\E'}
    };
    send_to_client(@_);
};

[download]

With a share-everything, it's not really clear how overwriting the globs should be handled. I would be for "overwriting (code) glob entries is discouraged" and there should/could be a strict 'thread-globs' pragma that prevents you from assigning to glob entries. This should prevent 95% of all those problems.

In reply to Re^3: Slow evolution of Perl = Perl is a closed Word (NQP, parrot concurrency == Oh dear.) by Corion
in thread Slow evolution of Perl = Perl is a closed Word by Anonymous Monk

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