Parallel processes: multi-core, same CPU?

[H J]

Leveraging fast shared memory access on the same (dual-core) CPU, I want to spawn two threads on each core of the same CPU. Is this possible with luajit? (I've been looking into `effil` but don't see how you can direct the task to a specific core...).

-- Henk 

[TopchetoEU]

This is a known limitation with lua - you can't run two lua threads (under the same lua_State) in parallel. AFAIK lua allows you to define some locking primitives, but they only serve to lock the current lua_State while lua code is executing, so in effect, only one lua thread is really executing at a time.

Your best bet is to create one lua_State per OS thread and device some kind of communication protocol between different lua states (since two states cannot share tables).

P.S.: Once upon a time I tried to rewrite the lua engine with parallelism in mind, but it was so hopefully slow I won't even dignify it with a link here.

On Thursday, June 11th, 2026 at 3:21 AM, H J <hjans...@gmail.com> wrote:

> Leveraging fast shared memory access on the same (dual-core) CPU, I want to spawn two threads on each core of the same CPU. Is this possible with luajit? (I've been looking into `effil` but don't see how you can direct the task to a specific core...).-- Henk
>

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[Benoit Germain]

Le dim. 14 juin 2026 à 16:22, 'TopchetoEU' via lua-l <lu...@googlegroups.com> a écrit :

This is a known limitation with lua - you can't run two lua threads (under the same lua_State) in parallel. AFAIK lua allows you to define some locking primitives, but they only serve to lock the current lua_State while lua code is executing, so in effect, only one lua thread is really executing at a time.

Your best bet is to create one lua_State per OS thread and device some kind of communication protocol between different lua states (since two states cannot share tables).

Shameless plug: one option is https://github.com/LuaLanes/lanes (there are others, but they can publicize themselves :-)).

--

Benoit.

[Norman Ramsey]

> > This is a known limitation with lua - you can't run two lua threads (under

> > the same lua_State) in parallel...

>
> Shameless plug: one option is https://github.com/LuaLanes/lanes (there are
> others, but they can publicize themselves :-)).

I have used Lua Lanes and gotten excellent speedups.


Norman

[H J]

Thanks for your suggestions.

AFAIK there are two candidates for parallel processing: `lanes` and (the newer) `effil`; they look similar to me but I have only experience with `effil`. Has anyone experience with both, and can share their relative pros and cons?

-- Henk

[云风 Cloud Wu]

H J <hjans...@gmail.com> 于2026年6月18日周四 08:12写道：

>
> Thanks for your suggestions.
> AFAIK there are two candidates for parallel processing: `lanes` and (the newer) `effil`; they look similar to me but I have only experience with `effil`. Has anyone experience with both, and can share their relative pros and cons?

I'd like to recommend my Lua task library ltask to the Lua community.
https://github.com/cloudwu/ltask

It is a flexible library that implements an n:m scheduler to run M Lua
states on N OS threads, and the lua services communicate via message
channels.

[Marc Balmer]

We us this scheme in production a lot, e.g. for https://trx-control.msys.ch

You find another approach at https://github.com/arcapos/mqlua where we
can create Lua states in separate POSIX threads and have them
communicate using ZeroMQ.