Re: Different behavior for coroutines in Lua and LuaJIT + Recycling Coroutines

[Graham Wakefield <lists@...>]

Thanks,

On Jun 15, 2008, at 12:36 PM, Mike Pall wrote:

> Graham Wakefield wrote:
> > Does this mean that using large numbers of coroutines (e.g. hundreds
> > concurrently, or hundreds of thousands over a program's lifetime)  
> > may be
> > more expensive in luajit 1.x than plain lua?
>
> Yes, unfortunately. At least if you need all of them to be alive
> at the same time.

That's too bad... but makes sense.

> Try to recycle coroutines instead of creating
> and collecting them repeatedly.

I did that in an earlier project... but I wasn't entirely confident  
that what I was doing was stable.

What I gathered from the list is that a coroutine that errors cannot  
be recycled, but one that returns with no error can have its stack  
cleared and be ready to be re-used.  I just wondered if there was any  
more to it that this; should I worry about any changes of  
environment, metatables etc. that may have had side effects on the  
lua_State, and which would lead to undefined behavior if recycled?

> The minimum amount of memory for a coroutine in LuaJIT 1.x is ~37K
> (and much more on Windows due to limitations of Windows Fibers).

Ouch.

> > And if so, is this also
> > likely to be the case in the eagerly anticipated luajit 2.0?
>
> No. The minimum amount of memory for a coroutine in LuaJIT 2.x
> will be ~450 bytes (thread object plus minimum Lua stack).

Great!