Re: Multi-threaded support for LUA

[Olivier Galibert <galibert@...>]

On Tue, Jul 29, 2008 at 05:57:25PM +0530, Vivek Gupta wrote:
> Hi,
> 
>  
> 
> I have a multi-threaded application in 'C' which invokes LUA functions.
> Because of the fact that LUA is a single threaded language I have used a
> global LUA state and used a mutex to serialize the access to global LUA
> state among the multiple threads. But this implementation has a
> performance bottleneck because of this serialization aspect.
> 
>  
> 
> To get rid of this serialization, is it feasible to maintain LUA state
> on a per thread basis? But I can foresee some issues with the LUA
> global. We might require synchronizing these LUA global variables. Has
> anyone tried this out? Some practical example would really help.

You can create a lua state per thread without any difficulty.  They
just won't share anything, which is not necessarily a problem, it
entirely depends on the specifics of your application.

In particular, how globals are your globals in the lua code?  Could
they be considered thread-local storage and things would still mostly
work, or are they a heavily used method of communication?  In the
second case, then your performance bottleneck is not due to lua, it is
due to having too much non-explicit communications between threads,
and the problem would be identical in C.  In the first case, though,
you can have the small amount of synchronizing communications done by
calling back into C through a number of appropriately designed
userdata objects.

  OG.