Re: When must I provide a self-defined lua_lock macro(e.g: #define lua_lock(L) pthread_lock(&mutex))?

[Victor Bombi <sonoro@...>]

> On January 28, 2021 at 10:17 AM 孙世龙 sunshilong <sunshilong369@gmail.com> wrote:
> 
> 
> Hi, list
> 
>     In general, the macro named lua_lock is expanded as a
> no-operation(i.e (void)0).
> 
>     Here is the related code snippet in Lua-5.3.5：
> /*
> ** macros that are executed whenever program enters the Lua core
> ** ('lua_lock') and leaves the core ('lua_unlock')
> */
> #if !defined(lua_lock)
> #define lua_lock(L) ((void) 0)
> #define lua_unlock(L) ((void) 0)
> #endif
> I wonder when I need to provide a self-defined macro (e.g:
>  #define lua_lock(L) pthread_lock(&mutex))?
> 
> I would appreciate it if you could shed some light on this question.
> 
> Best regards

Lua is not multithread ready unless you define lua_lock. But providing lua_lock you will get a multithreaded Lua very difficult to use, there will be deadlock problems difficult to solve.
The best way to use Lua in a multithread environment is to create a different lua_State in each thread and let all different lua_States to inter-communicate. I would recomend using LuaLanes for achieving this althought there are a lot of alternatives.

Best
Victor Bombí
> sunshilong