Re: Patch: fix lock contention for HASHHDR.mutex

On Sat, Mar 19, 2016 at 7:02 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Sat, Mar 19, 2016 at 12:28 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
> > Won't in theory, without patch as well nentries can overflow after
running
> > for very long time? I think with patch it is more prone to overflow
because
> > we start borrowing from other free lists as well.
>
> Uh, I don't think so. Without the patch, there is just one entries
> counter and it goes up and down. How would it ever overflow?
>

I thought it can overflow because we haven't kept any upper limit on
incrementing it unless the memory finishes (ofcourse that is just a
theoretical assumption, as the decrements will keep the number in control),
so are you thinking about the risk of overflow with patch because we have
to use sum of all the nentries from all the arrays for total or is there
any thing else which makes you think that changing nentries into arrays of
nentries can make it prone to overflow?

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com