Re: bug of GC "step"

[Irayo <irayo.lt@...>]

Mauro Iazzi wrote:
> On my computer (x86_64) this runs well. Using -m32 to generate 32 bit
> code recreates the freeze.
>
> However it seems to me that this is not a bug. If you read the
> definitions of the gc parameters, you will see that you are asking the
> collector to start whenever the memory grows over 100% of what's
> currently used.
>
> If a collection cycle has just finished then it cannot reclaim any
> memory, and whatever threshold it wants to get under (probably a
> percentage of current), it cannot reach it. Thus it remains in the
> loop you have seen. Try using collectgarbage("setpause", 101) : it
> seems to fix things here.
>
>    
I would agree that it's not a bug, then.  Lua could throw an error, but 
that just adds an extra check to the garbage collection.  I think it'd 
be sufficient and easier to put a notice about it in the manual ("asking 
the GC to collect when memory grows to 100% of its current size will 
cause an infinite loop" or some such).  I don't think it would be enough 
of an issue to actually code a specific check for it, but that's 
certainly an option as well.  I guess GC operations take long enough 
that a couple extra machine instructions wouldn't hurt.

Another interesting question is why the 64-bit Lua can do it just fine.  
Any thoughts?

--
Irayo