Re: Double shared memory allocation for SLRU LWLocks

On Wed, Jul 12, 2017 at 2:03 PM, Teodor Sigaev <teodor(at)sigaev(dot)ru> wrote:

> It seems to me that we're allocating shared memory for SLRU lwlocks twice,
>> unless I'm missing something.
>>
> I think you are right.
>
> Did you check previous versions? i.e. should it be applyed to previous
> branches?? I suppose yes, to minimize code difference.
>

Problem was introduced by fe702a7b. I think it would be good to backpatch
to 9.6. Besides it doesn't cause any user-visible problem, nevertheless
it's a bug.

> Also I'd like an idea to add Assert(offset <= SimpleLruShmemSize(nslots,
> nlsns)) at the end of SimpleLruInit()

Good point. Please, find it in attached patch.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company