Re: Escaping from blocked send() reprised.

On Mon, Jun 30, 2014 at 11:26 PM, Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>> 2. I think it would be reasonable to try to kill off the connection
>> without notifying the client if we're unable to send the data to the
>> client in a reasonable period of time. But I'm unsure what "a
>> reasonable period of time" means. This patch would basically do it
>> after no delay at all, which seems like it might be too aggressive.
>> However, I'm not sure.
>
> I think there's no such a reasonable time. The behavior might
> should be determined from another point.. On alternative would be
> let pg_terminate_backend() have a parameter instructing force
> shutodwn (how to propagate it?), or make a forced shutdown on
> duplicate invocation of pg_terminate_backend().

Well, I think that when people call pg_terminate_backend() just once,
they expect it to kill the target backend. I think people will
tolerate a short delay, like a few seconds; after all, there's no
guarantee, even today, that the backend will hit a
CHECK_FOR_INTERRUPTS() in less than a few hundred milliseconds. But
they are not going to want to have to take a second action to kill the
backend - killing it once should be sufficient.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company