Question about threads

[Antero Vipunen <antero@...>]

Hello All,

 I use such an architecture in my Mud(i'm writing Lua based triggers):
  there is MainState(=lua_open()) and for each new script I create a new
  thread(= lua_newthread(MainState)).
  
 The questions are:
  0. Can I free threads manually or they can be only
  garbage-collected?
  1. Can I force thread to be garbage-collected when the
  script running in this thread finishes execution?
  2. Can I force thread to be garbage-collected even if
  script running in this thread is yielded?

-- 
Best regards,
 Antero Vipunen