Re: [PATCH] Fix crash in int8_avg_combine().

On Sat, Nov 25, 2017 at 10:47 PM, Andres Freund <andres(at)citusdata(dot)com>
wrote:

> diff --git a/src/include/utils/memutils.h b/src/include/utils/memutils.h
> > index 869c59dc85..2dc59e89cd 100644
> > --- a/src/include/utils/memutils.h
> > +++ b/src/include/utils/memutils.h
> > @@ -189,7 +189,7 @@ extern MemoryContext SlabContextCreate(MemoryContext
> parent,
> > * Few callers should be interested in this, but tuplesort/tuplestore
> need
> > * to know it.
> > */
> > -#define ALLOCSET_SEPARATE_THRESHOLD 8192
> > +#define ALLOCSET_SEPARATE_THRESHOLD 16384
>
> Huh, what's that about in this context?
>

There is following static assert:

StaticAssertStmt(ALLOC_CHUNK_LIMIT == ALLOCSET_SEPARATE_THRESHOLD, ...)

and ALLOCK_CHUNK_LIMIT is defined as:

#define ALLOC_CHUNK_LIMIT (1 << (ALLOCSET_NUM_FREELISTS-1+ALLOC_MINBITS))

and there is this comment:

"CAUTION: ALLOC_MINBITS must be large enough so that 1<<ALLOC_MINBITS is at
least MAXALIGN, ..."

So I increased ALLOC_MINBITS which resulted in doubling
ALLOCSET_SEPARATE_THRESHOLD.

Thanks,
-- Hadi