Re: Is it possible to run Lua threads in OS threads safely?

[Norman Ramsey <nr@...>]

 > There seem to be a dedicated page on lua-users wiki:
 > http://lua-users.org/wiki/MultiTasking
 > ...
 >    - *LuaProc *seems to be the official tool from Lua development Team
 >    (RI), but seems not to be maintained any more
 >    https://github.com/askyrme/luaproc, the original doc is
 >    http://www.inf.puc-rio.br/~roberto/docs/ry08-05.pdf, a more recent doc
 >    https://www.maxwell.vrac.puc-rio.br/30267/30267.PDF (seems to be about a
 >    2018 modified version)
 >       - *Why in the user-lua wiki it is classified as "cooperative" and not
 >       "preemptive"?* (it enables but user-level and OS-level parallelism,
 >       so I guess it is cooperative at the user level and preemptive at the
 >       OS-level.... is this correct?)
 > 
 > Does anyone has done some trial to assess pros/cons and performance?

I have been using luaproc for about three years.

Pros:

  - Relatively simple model
  - Excellent speedups (basically 4x speedup on 4-core machine)
  - Mostly reliable
  - Scalar data is relatively easy to pass between threads (as upvalues)

Cons:

  - The concurrency model is a bit limiting, and it took me a while to
    figure out how to use it effectively.  (Details forgotten, alas.)
  - Some code has to be written in strings, so you may not find syntax
    errors as soon or as easily as you might like.
  - To pass table values between threads, I wound up writing my own
    serializer/deserializer. 
  - Occasionally a computation locks up on a mysterious way.  Could
    be luaproc or could be the C library we're using to interact with
    the Unix pty interface.

On the whole I'd recommend it.


Norman