From: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
---|---|
To: | Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> |
Cc: | Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp>, Stas Kelvich <s(dot)kelvich(at)postgrespro(dot)ru>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Add client connection check during the execution of the query |
Date: | 2021-03-01 05:18:17 |
Message-ID: | CA+hUKGJd0XTiJ08V-HEEb=Jy6GmUNO0ht6FF5dN9JhXOmJ78Mg@mail.gmail.com |
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On Sat, Aug 3, 2019 at 4:40 AM Konstantin Knizhnik
<k(dot)knizhnik(at)postgrespro(dot)ru> wrote:
> On 18.07.2019 6:19, Tatsuo Ishii wrote:
> > So the performance is about 5% down with the feature enabled in this
> > case. For me, 5% down is not subtle. Probably we should warn this in
> > the doc.
>
> I also see some performance degradation, although it is not so large in
> my case (I used pgbench with scale factor 10 and run the same command as
> you).
> In my case difference is 103k vs. 105k TPS is smaller than 2%.
I didn't test, but hopefully the degradation is fixed by commit 09cf1d52?
> If OS detected closed connection, it should return POLLHUP, should not it?
> I am not sure if it is more portable or more efficient way - just seems
> to be a little bit more natural way (from my point of view) to check if
> connection is still alive.
That's if you're sleeping inepoll etc. This patch is for CPU-bound
backends, running a long query. We need to do something special to
find out if the kernel knows that the connection has been closed.
I've done a quick rebase of this the patch and added it to the
commitfest. No other changes. Several things were mentioned earlier
that still need to be tidied up.
Attachment | Content-Type | Size |
---|---|---|
v3-0001-Detect-dropped-connections-while-running-queries.patch | text/x-patch | 14.6 KB |
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