Re: [HACKERS] Query cancel and OOB data

Bruce Momjian wrote:
>
Bruce Momjian wrote:
>
> Yea, I found that too, late last night, Section 6.14, page 332.
>
> I basically need some way to 'signal' the backend of a cancellation
> request. Polling the socket is not an option because it would impose
> too great a performance penalty. Maybe async-io on a read(), but that
> is not going to be very portable.
>
> I could pass the backend pid to the front end, and send a kill(SIG_URG)
> to that pid on a cancel, but the frontend can be running as a different
> user than the backend. Problem is, the only communcation channel is
> that unix domain socket.
>
> We basically need some way to get the attention of the backend,
> hopefully via some signal.
>
> Any ideas?

postmaster could be listening (adding to select()) on a "signal socket"
for cancel request and shot down its children on request.

how do we make such a scheme secure ??

terveiset,
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Göran Thyni, sysadm, JMS Bildbasen, Kiruna