> Markets are a funny thing. Both "dead" languages are thread safe and can easily run separate interpreters per thread.
Perl threading is officially recommended against IIRC? In either case, "threads" in either of them don't share memory (except explicitly and manually), at which point what you have is multiprocessing by a different name.
In Perl 5 threading things are only "shared" semantically. In reality, there is an extra interpreter running where the "shared" variables live, and any value fetches and stores are handled with the `tie` interface (see http://www.perlmonks.org/?node_id=288022 for more information).
In Perl 6 on the other hand, everything is always shared and you can use high level constructs such as atomic increments, supplies, taps, `react` and `whenever` so you don't have to think about any (dead)locking issues as a developer.
Tcl has an "easy" threading mode where each thread runs its own interpreter, and a "hold my beer" mode where you can spawn threads within a single interpreter.
Tcl also has synthetic channels, so you can stay in easy mode but open a bi-directional read/write channel with the two ends in separate threads, with readable/writable events assigned, so you can do automatic event-driven information sharing between threads.
I don't know any other language that gives you options like that.
