How to pass data between multiple Lua State(multi-thread)?

Question

I initiate Redis connection pool in redis.lua, by calling from C, I got a redis_lua_state, this Lua state is global initiated once and other thread only get from it.

While there comes a HTTP request(worker thread), I need to fetch a redis connection from redis_lua_state, then new another Lua state to load other Lua script, and these scripts will use this redis connection to communicate with Redis, how to do this? Or how to design my Lua scripts to make it simple?

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Code Sample:

    /* on main thread, to init redis pool connection */
    lua_State *g_ls = NULL;
    lua_State *init_redis_pool(void) {
            int ret = 0;
            g_ls = luaL_newstate();
            lua_State *ls = g_ls;

            luaL_openlibs(ls);
            ret = luaL_loadfile(ls, "redis.lua");
            const char *err;
            (void)err;

            /* preload */
            ret = lua_pcall(ls, 0, 0, 0);

            lua_getglobal(ls, "init_redis_pool");
            ret = lua_pcall(ls, 0, 0, 0);

            return ls;
    }

    /* worker thread */
    int worker() {
            ...
            lua_State *ls = luaL_newstate();
            ret = luaL_loadfile(ls, "run.lua");

            /* How to fetch data from g_ls? */
            ...
            lua_getglobal(ls, "run")
            ret = lua_pcall(ls, 0, 0, 0)

            lua_close(ls);
            ...
            return 0;
    }

Answer 1

If your Lua states are separate, then there's no way to do this. Your worker thread will have to initialize the Redis connection and do processing on it.