Re: Odd looking code in lmem.c

[Thomas Jericke <tjericke@...>]

On 06/26/2014 07:26 AM, Paige DePol wrote:
> On Jun 25, 2014, at 11:26 PM, Daurnimator <quae@daurnimator.com> wrote:
>
> > Today I was reading the lua source, and came across this code in lmem.c ( http://www.lua.org/source/5.2/lmem.c.html#luaM_realloc_ )
> >
> >      if (g->gcrunning) {
> >        luaC_fullgc(L, 1);  /* try to free some memory... */
> >
> > Is that conditional accidentally reversed?
> > Why run the gc again ONLY if the gc is mid-run?
> > Wouldn't it make sense to run the gc if it's NOT already running?
> >
> > Sorry if this is a stupid question >.<
> >
> > Daurn.
> If the realloc routine fails to allocate memory, and the garbage collector is running, then it will attempt to do a full garbage collection cycle (in emergency mode) in the effort to free memory.
>
> The allocation is then tried again, and if it fails a memory error is thrown. If the garbage collector is not active then this emergency collection will not occur.
>
> Note that the `g->gcrunning` flag only indicates if the garbage collector is running, not if it is in the middle of a run or any other status other than active or inactive.
>
> ~pmd

Now that explains why the emergency gc didn't run when I ran out of 
memory. I have disabled the GC and run it in steps when my system is idle.

Now I am wondering if there is an option to turn the GC of but still 
enable the emergency GC.
--
Thomas