Re: Cloning "preforked" Lua state

[Michael Surette <mjsurette@...>]

 

----- Original Message -----

From: Phoenix Sol

Sent: 09/06/09 11:17 am

To: Lua list

Subject: Re: Cloning "preforked" Lua state

 

>>From http://stackoverflow.com/questions/1383768/cloning-lua-state/1383847

I was thinking about using coroutines however I'm afraid a fatal error in one coroutine will affect others that's why it's not option atm. Thanks for the links! I'm currently looking at LuaJIT and Rings. Rings seems to be a possible solution for my problem.

What can an error do inside a coroutine (a lua_State created with lua_newthread), that it could not do inside a lua_State created with lua_newstate?

lua_newthread gives you a garbage collected lua_State with all the globals of your original state. Is this not what you want?

Asko, why would a server want to call lua_newstate or luaL_newstate for each request, instead of lua_newthread?

Please tell me what I'm missing here.

 

All threads would use the same ***instance*** of all globals, so if you save something in a global variable in one thread, it affects all threads.  This is a very undesirable trait in server threads.  If you forget to make a variable local and write to it you have a problem.  This then gives us the the problem of context, that is saving state from one subroutine call to another in a given thread.  You can't use globals.  In the past I've used per-thread tables that I pass to all subroutines, which works, but this idea of cloning threads sounds like it might be a more natural feeling solution to this problem.

Mike