optimize: we no longer clear the lua_State pointers for dead "light threads" such that their coroutine context structs could be reused by other "light threads" and user coroutines.

Author: agentzh

src/ngx_http_lua_util.c

@@ -363,7 +363,6 @@ ngx_http_lua_del_thread(ngx_http_request_t *r, lua_State *L,
     luaL_unref(L, -1, coctx->co_ref);
     coctx->co_ref = LUA_NOREF;
     coctx->co_status = NGX_HTTP_LUA_CO_DEAD;
-    coctx->co = NULL;
 
     lua_pop(L, 1);
 }
@@ -396,7 +395,6 @@ ngx_http_lua_del_all_threads(ngx_http_request_t *r, lua_State *L,
                 ctx->uthreads--;
             }
 
-            cc->co = NULL;
             cc->co_status = NGX_HTTP_LUA_CO_DEAD;
         }
 
@@ -435,7 +433,6 @@ ngx_http_lua_del_all_threads(ngx_http_request_t *r, lua_State *L,
                 luaL_unref(L, -1, ref);
                 cc[i].co_ref = LUA_NOREF;
                 cc[i].co_status = NGX_HTTP_LUA_CO_DEAD;
-                cc[i].co = NULL;
                 ctx->uthreads--;
 
                 if (ctx->uthreads == 0) {
@@ -461,7 +458,6 @@ ngx_http_lua_del_all_threads(ngx_http_request_t *r, lua_State *L,
         luaL_unref(L, -1, entry_coctx->co_ref);
         entry_coctx->co_ref = LUA_NOREF;
         entry_coctx->co_status = NGX_HTTP_LUA_CO_DEAD;
-        entry_coctx->co = NULL;
     }
 
     if (inited) {