lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = tostate(luaM_malloc(L, state_size(lua_State)));
  luaC_link(L, obj2gco(L1), LUA_TTHREAD);
  preinit_state(L1, G(L));
  stack_init(L1, L);  /* init stack */
  setobj2n(L, gt(L1), gt(L));  /* share table of globals */
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  lua_assert(iswhite(obj2gco(L1)));
  return L1;
}