Coding in Lua, I have a triply nested loop that goes through 6000 iterations. All 6000 iterations are independent and can easily be parallelized. What threads package for Lua compiles out of the box and gets decent parallel speedups on four or more cores?

Here's what I know so far:

luaproc comes from the core Lua team, but the software bundle on luaforge is old, and the mailing list has reports of it segfaulting. Also, it's not obvious to me how to use the scalar message-passing model to get results ultimately into a parent thread.

Lua Lanes makes interesting claims but seems to be a heavyweight, complex solution. Many messages on the mailing list report trouble getting Lua Lanes to build or work for them. I myself have had trouble getting the underlying "Lua rocks" distribution mechanism to work for me.

LuaThread requires explicit locking and requires that communication between threads be mediated by global variables that are protected by locks. I could imagine worse, but I'd be happier with a higher level of abstraction.

Concurrent Lua provides an attractive message-passing model similar to Erlang, but it says that processes do not share memory. It is not clear whether spawn actually works with any Lua function or whether there are restrictions.

Russ Cox proposed an occasional threading model that works only for C threads. Not useful for me.

I will upvote all answers that report on actual experience with these or any other multithreading package, or any answer that provides new information.

For reference, here is the loop I would like to parallelize:

for tid, tests in pairs(tests) do local results = { } matrix[tid] = results for i, test in pairs(tests) do if test.valid then results[i] = { } local results = results[i] for sid, bin in pairs(binaries) do local outcome, witness = run_test(test, bin) results[sid] = { outcome = outcome, witness = witness } end end end end