Re: could not create IPv6 socket (AI_ADDRCONFIG)

Hello,

At Tue, 04 Feb 2014 02:07:08 -0500, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in <3176(dot)1391497628(at)sss(dot)pgh(dot)pa(dot)us>
> One good reason not to trust this too much is that getaddrinfo() is
> fundamentally a userspace DNS access function, and as such it has
> no very good way to know if there's currently an IPv4 or IPv6
> interface configured on the local system. At minimum there are
> obvious race conditions in that.

A case which would be more common is "::1" in /etc/hosts. I had
following error with this patch for such a case.

| LOG: could not bind IPv4 socket: Address already in use
| HINT: Is another postmaster already running on port 5432? If not, wait a few seconds and retry.

getaddrinfo returned two same entries having the same address
AF_INET "127.0.0.1:14357". One of them is for "::1" in
hosts. This is worse than current behavior X-(

At Tue, 04 Feb 2014 10:31:03 -0500, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in <12552(dot)1391527863(at)sss(dot)pgh(dot)pa(dot)us>
> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> > Tom Lane wrote:
> >> Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> writes:
> >>> LOG: could not create IPv6 socket: Address family not supported by protocol
>
> >> That's merely a harmless log message.
>
> > How about just adding a HINT?
>
> Hmm ... maybe, but how would you phrase the hint exactly?

Putting the 'exactly' aside, is it something means 'You will get
this message when the feature to handle the address family is
disabled', only for EAFNOSUPPORT ?

Though I don't know whether such a hint is helpful for those who
tend to mind that kind of message.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center