Re: Proposal: "Causal reads" mode for load balancing reads without stale data - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Proposal: "Causal reads" mode for load balancing reads without stale data
Date
Msg-id 20160505013744.ainxtyzy4umakq65@alap3.anarazel.de
Whole thread Raw
In response to Re: Proposal: "Causal reads" mode for load balancing reads without stale data  (Thomas Munro <thomas.munro@enterprisedb.com>)
List pgsql-hackers
On 2016-05-05 13:30:42 +1200, Thomas Munro wrote:
> That was a red herring.  I was confused because SUSv2 and POSIX call
> this argument 'errorfds' and say that sockets *also* tell you about
> errors this way.  (Many/most real OSs call the argument 'exceptfds'
> instead and only use it to tell you about out-of-band data and
> possibly implementation specific events for devices, pseudo-terminals
> etc.  If you want to know about errors on a socket it's enough to have
> it in readfds/writefds, and insufficient to have it only in
> errorfds/exceptfds unless you can find a computer that actually
> conforms to POSIX.)

Correct, exceptfds is pretty much meaningless for anything we do in
postgres. We rely on select returning a socket as read/writeable if the
socket has hung up.  That's been the case *before* the recent
WaitEventSet refactoring, so I think we're fairly solid on relying on
that.

Greetings,

Andres Freund



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