Re: keepalives on MacOS X

It looks like the recent keepalives patch won't support MacOS X,
because MacOS X does not have the TCP_KEEPIDLE, TCP_KEEPINTVL, and
TCP_KEEPCNT socket parameters. It does have this:

#define TCP_KEEPALIVE 0x10 /* idle time used when
SO_KEEPALIVE is enabled */

Should we try to support that as a synonym for TCP_KEEPIDLE, if that's
what it is? Or not worry about it? Or... what?

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

On Tue, Jun 29, 2010 at 4:07 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> It looks like the recent keepalives patch won't support MacOS X,
> because MacOS X does not have the TCP_KEEPIDLE, TCP_KEEPINTVL, and
> TCP_KEEPCNT socket parameters.  It does have this:
>
> #define TCP_KEEPALIVE           0x10    /* idle time used when
> SO_KEEPALIVE is enabled */
>
> Should we try to support that as a synonym for TCP_KEEPIDLE, if that's
> what it is?  Or not worry about it?  Or... what?

I'm not sure that can be a synonym for TCP_KEEPIDLE, but if so we should
change not only a client-side but also server-side.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> It looks like the recent keepalives patch won't support MacOS X,
> because MacOS X does not have the TCP_KEEPIDLE, TCP_KEEPINTVL, and
> TCP_KEEPCNT socket parameters. It does have this:

It looks to me like there's support for setting KEEPIDLE and KEEPINTVL
via sysctl, but of course that's system-wide and presumably requires
root privilege to set. (Apple seems to have inherited that from various
BSDen, btw; it's not unique to Darwin.)

> #define TCP_KEEPALIVE 0x10 /* idle time used when
> SO_KEEPALIVE is enabled */

> Should we try to support that as a synonym for TCP_KEEPIDLE, if that's
> what it is? Or not worry about it? Or... what?

Yeah, a bit of rooting around in the Darwin sources shows that this
value is used as a per-connection override for tcp_keepidle. So it
is a synonym. Not sure if it's worth supporting when the other value
can't be set too. Maybe it'd be more useful to document that people can
set the system-wide values if they're desperate.

regards, tom lane

On Tue, Jun 29, 2010 at 12:42 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Yeah, a bit of rooting around in the Darwin sources shows that this
> value is used as a per-connection override for tcp_keepidle.  So it
> is a synonym.  Not sure if it's worth supporting when the other value
> can't be set too.  Maybe it'd be more useful to document that people can
> set the system-wide values if they're desperate.

Well, the default value for tcp_keepidle is 2 hours, and the default
value for tcp_keepintvl is 75 seconds. Assuming that tcp_keepcount
defaults to something reasonable (I think the default on Linux is 9),
the lion's share of the time will be waiting for tcp_keepidle - so
just the ability to reduce that value to something reasonable should
help a lot. It's also not much code - proposed patch attached.

Some documentation of how to change this stuff via sysctl on various
OSes wouldn't be a bad thing either - anyone feel like writing
something up?

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

On Tue, Jun 29, 2010 at 11:28 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Jun 29, 2010 at 12:42 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Yeah, a bit of rooting around in the Darwin sources shows that this
>> value is used as a per-connection override for tcp_keepidle.  So it
>> is a synonym.  Not sure if it's worth supporting when the other value
>> can't be set too.  Maybe it'd be more useful to document that people can
>> set the system-wide values if they're desperate.
>
> Well, the default value for tcp_keepidle is 2 hours, and the default
> value for tcp_keepintvl is 75 seconds.  Assuming that tcp_keepcount
> defaults to something reasonable (I think the default on Linux is 9),
> the lion's share of the time will be waiting for tcp_keepidle - so
> just the ability to reduce that value to something reasonable should
> help a lot.  It's also not much code - proposed patch attached.

src/interfaces/libpq/fe-connect.c
+ appendPQExpBuffer(&conn->errorMessage,
+ libpq_gettext("setsockopt(TCP_KEEPIDLE) failed: %s\n"),
+ SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));

s/TCP_KEEPIDLE/TCP_KEEPALIVE

Don't we need to change pq_getkeepalivesidle?

In pq_setkeepalivesidle, if neither TCP_KEEPIDLE nor TCP_KEEPALIVE are
supported, the following message is output.

setsockopt(TCP_KEEPIDLE) not supported

We should change it to something like?

neither setsockopt(TCP_KEEPIDLE) nor setsockopt(TCP_KEEPALIVE) are supported

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

On Tue, Jun 29, 2010 at 10:53 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Tue, Jun 29, 2010 at 11:28 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Tue, Jun 29, 2010 at 12:42 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> Yeah, a bit of rooting around in the Darwin sources shows that this
>>> value is used as a per-connection override for tcp_keepidle.  So it
>>> is a synonym.  Not sure if it's worth supporting when the other value
>>> can't be set too.  Maybe it'd be more useful to document that people can
>>> set the system-wide values if they're desperate.
>>
>> Well, the default value for tcp_keepidle is 2 hours, and the default
>> value for tcp_keepintvl is 75 seconds.  Assuming that tcp_keepcount
>> defaults to something reasonable (I think the default on Linux is 9),
>> the lion's share of the time will be waiting for tcp_keepidle - so
>> just the ability to reduce that value to something reasonable should
>> help a lot.  It's also not much code - proposed patch attached.
>
> src/interfaces/libpq/fe-connect.c
> +               appendPQExpBuffer(&conn->errorMessage,
> +                                                 libpq_gettext("setsockopt(TCP_KEEPIDLE) failed: %s\n"),
> +                                                 SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
>
> s/TCP_KEEPIDLE/TCP_KEEPALIVE

Fixed.

> Don't we need to change pq_getkeepalivesidle?

I changed this, but it doesn't seem to have done much. When I do
"show tcp_keepalives_idle" on MacOS X, I still get 0. gdb says
getsockopt is getting called, though. Am I doing something boneheaded
here, or is this just the behavior?

> In pq_setkeepalivesidle, if neither TCP_KEEPIDLE nor TCP_KEEPALIVE are
> supported, the following message is output.
>
>    setsockopt(TCP_KEEPIDLE) not supported

Fixed.

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

On Fri, Jul 2, 2010 at 5:44 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Jun 29, 2010 at 10:53 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>> On Tue, Jun 29, 2010 at 11:28 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Tue, Jun 29, 2010 at 12:42 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>> Yeah, a bit of rooting around in the Darwin sources shows that this
>>>> value is used as a per-connection override for tcp_keepidle.  So it
>>>> is a synonym.  Not sure if it's worth supporting when the other value
>>>> can't be set too.  Maybe it'd be more useful to document that people can
>>>> set the system-wide values if they're desperate.
>>>
>>> Well, the default value for tcp_keepidle is 2 hours, and the default
>>> value for tcp_keepintvl is 75 seconds.  Assuming that tcp_keepcount
>>> defaults to something reasonable (I think the default on Linux is 9),
>>> the lion's share of the time will be waiting for tcp_keepidle - so
>>> just the ability to reduce that value to something reasonable should
>>> help a lot.  It's also not much code - proposed patch attached.
>>
>> src/interfaces/libpq/fe-connect.c
>> +               appendPQExpBuffer(&conn->errorMessage,
>> +                                                 libpq_gettext("setsockopt(TCP_KEEPIDLE) failed: %s\n"),
>> +                                                 SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
>>
>> s/TCP_KEEPIDLE/TCP_KEEPALIVE
>
> Fixed.
>
>> Don't we need to change pq_getkeepalivesidle?
>
> I changed this, but it doesn't seem to have done much.  When I do
> "show tcp_keepalives_idle" on MacOS X, I still get 0.  gdb says
> getsockopt is getting called, though.  Am I doing something boneheaded
> here, or is this just the behavior?
>
>> In pq_setkeepalivesidle, if neither TCP_KEEPIDLE nor TCP_KEEPALIVE are
>> supported, the following message is output.
>>
>>    setsockopt(TCP_KEEPIDLE) not supported
>
> Fixed.

Committed, after some further testing.

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