Обсуждение: slower connect from hostnossl clients
Hi
I am testing speed of connection to Postgres. On Tue, Jun 7, 2016 at 11:24 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
Is it expected behave?The ssl connection is slower, and it is expected. But when I configure pg_hba.conf to disable ssl via hostnossl, then ssl is not used, but the speed is similar to ssl.HiI am testing speed of connection to Postgres.
That's definitely not expected behavior. hostnossl should turn off ssl which should turn off the overhead completely. Does it make a difference if you also disable it from the client side?
2016-06-07 11:29 GMT+02:00 Magnus Hagander <magnus@hagander.net>:
On Tue, Jun 7, 2016 at 11:24 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:Is it expected behave?The ssl connection is slower, and it is expected. But when I configure pg_hba.conf to disable ssl via hostnossl, then ssl is not used, but the speed is similar to ssl.HiI am testing speed of connection to Postgres.That's definitely not expected behavior. hostnossl should turn off ssl which should turn off the overhead completely. Does it make a difference if you also disable it from the client side?
When I explicitly disabled ssl, then I seen significantly less time
Regards
Pavel
--
On Tue, Jun 7, 2016 at 11:31 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
2016-06-07 11:29 GMT+02:00 Magnus Hagander <magnus@hagander.net>:On Tue, Jun 7, 2016 at 11:24 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:Is it expected behave?The ssl connection is slower, and it is expected. But when I configure pg_hba.conf to disable ssl via hostnossl, then ssl is not used, but the speed is similar to ssl.HiI am testing speed of connection to Postgres.That's definitely not expected behavior. hostnossl should turn off ssl which should turn off the overhead completely. Does it make a difference if you also disable it from the client side?When I explicitly disabled ssl, then I seen significantly less time
Intersting. Can you check with a network trace that it actually turns off ssl, so nothing is broken there?
One thing that could be taking the time is an extra roundtrip -- e.g. it tries to connect with ssl fails and retries without. A network trace should also make this obvious, and can hopefully show you exactly where in the connection the time is spent.
On 06/07/2016 12:18 PM, Magnus Hagander wrote:> Intersting. Can you check with a network trace that it actually turns> offssl, so nothing is broken there?>> One thing that could be taking the time is an extra roundtrip -- e.g. it> tries toconnect with ssl fails and retries without. A network trace> should also make this obvious, and can hopefully show youexactly where> in the connection the time is spent. I think this is to be expected given that the backend code initializes the TLS connection before it looks at anything in pg_hba.conf. The TLS connection setup is done when calling BackendInitialize() which happens very early in the life of a backend. I am not familiar enough with this part of the code to know if there is a reasonable way to fix this. Andreas
On Tue, Jun 7, 2016 at 12:41 PM, Andreas Karlsson <andreas@proxel.se> wrote:
Interesting, hadn't thought of that. I guess it can be - but it would definitely be good to identify if that's really the case. If it is there is definitely some optimization to be done there.
On 06/07/2016 12:18 PM, Magnus Hagander wrote:
> Intersting. Can you check with a network trace that it actually turns
> off ssl, so nothing is broken there?
>
> One thing that could be taking the time is an extra roundtrip -- e.g. it
> tries to connect with ssl fails and retries without. A network trace
> should also make this obvious, and can hopefully show you exactly where
> in the connection the time is spent.
I think this is to be expected given that the backend code initializes the TLS connection before it looks at anything in pg_hba.conf. The TLS connection setup is done when calling BackendInitialize() which happens very early in the life of a backend.
I am not familiar enough with this part of the code to know if there is a reasonable way to fix this.
Hm. You're saying it's the actual loading-of-certificate-and-setting-up-context that's slowing it down, not the actual connection step?
Interesting, hadn't thought of that. I guess it can be - but it would definitely be good to identify if that's really the case. If it is there is definitely some optimization to be done there.
2016-06-07 12:18 GMT+02:00 Magnus Hagander <magnus@hagander.net>:
On Tue, Jun 7, 2016 at 11:31 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:2016-06-07 11:29 GMT+02:00 Magnus Hagander <magnus@hagander.net>:On Tue, Jun 7, 2016 at 11:24 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:Is it expected behave?The ssl connection is slower, and it is expected. But when I configure pg_hba.conf to disable ssl via hostnossl, then ssl is not used, but the speed is similar to ssl.HiI am testing speed of connection to Postgres.That's definitely not expected behavior. hostnossl should turn off ssl which should turn off the overhead completely. Does it make a difference if you also disable it from the client side?When I explicitly disabled ssl, then I seen significantly less timeIntersting. Can you check with a network trace that it actually turns off ssl, so nothing is broken there?
I tested it on local only. The difference is +/- 5-10 ms, but it is well visible
My customer tested it on network, but on Windows, and there difference is about 100ms
Pavel
One thing that could be taking the time is an extra roundtrip -- e.g. it tries to connect with ssl fails and retries without. A network trace should also make this obvious, and can hopefully show you exactly where in the connection the time is spent.
See attached log
My pg_hba.conf
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all trust
# IPv4 local connections:
hostnossl all all 10.151.1.41/32 trust
# IPv6 local connections:
host all all ::1/128 trust
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all trust
# IPv4 local connections:
hostnossl all all 10.151.1.41/32 trust
# IPv6 local connections:
host all all ::1/128 trust
connection string
host=10.151.1.41 port=5432 dbname=postgres user=pavel
host=10.151.1.41 port=5432 dbname=postgres user=pavel
Regards
Pavel
--
Вложения
Magnus Hagander <magnus@hagander.net> writes:
> One thing that could be taking the time is an extra roundtrip -- e.g. it
> tries to connect with ssl fails and retries without.
I'd assume a priori that that's it. If so, the fix is to configure libpq
to try non-SSL first not SSL first. There is an option for that, IIRC.
regards, tom lane
At Tue, 7 Jun 2016 12:18:31 +0200, Magnus Hagander <magnus@hagander.net> wrote in <CABUevEz5qRmq4EbYsBZ+uJfg_3_ap361ZQtgbH_eF+2j6P0zag@mail.gmail.com> > On Tue, Jun 7, 2016 at 11:31 AM, Pavel Stehule <pavel.stehule@gmail.com> > wrote: > >> That's definitely not expected behavior. hostnossl should turn off ssl > >> which should turn off the overhead completely. Does it make a difference if > >> you also disable it from the client side? > >> > > > > When I explicitly disabled ssl, then I seen significantly less time > > > > > Intersting. Can you check with a network trace that it actually turns off > ssl, so nothing is broken there? > > One thing that could be taking the time is an extra roundtrip -- e.g. it > tries to connect with ssl fails and retries without. A network trace should > also make this obvious, and can hopefully show you exactly where in the > connection the time is spent. As Tom said, setting sslmode=allow or disable prevents reconnection against hostnossl. > psql "sslmode=disable host=127.0.0.1 dbname=postgres" There are 4 (disable, allow, prefer, require) * 3 (host, hostssl, hostnossl) = 12 possible combinations (ignoring veryfy-* of sslmode) of SSL usage preferences. Among these, the following two combinations needs reconnection. prefer + hostnossl , allow + hostssl Since no client can find whether a user can connect using (or not using) SSL before making any connection, reconnection is inevitable for the above combinations. By the way, SSL initialization takes place only when server is requested SSL connection (NEGOTIATE_SSL_MODE), so only prefer + hostnossl causes the wasting SSL intialization. regards, -- Kyotaro Horiguchi NTT Open Source Software Center
2016-06-08 8:26 GMT+02:00 Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>:
At Tue, 7 Jun 2016 12:18:31 +0200, Magnus Hagander <magnus@hagander.net> wrote in <CABUevEz5qRmq4EbYsBZ+uJfg_3_ap361ZQtgbH_eF+2j6P0zag@mail.gmail.com>
> On Tue, Jun 7, 2016 at 11:31 AM, Pavel Stehule <pavel.stehule@gmail.com>
> wrote:
> >> That's definitely not expected behavior. hostnossl should turn off ssl
> >> which should turn off the overhead completely. Does it make a difference if
> >> you also disable it from the client side?
> >>
> >
> > When I explicitly disabled ssl, then I seen significantly less time
> >
> >
> Intersting. Can you check with a network trace that it actually turns off
> ssl, so nothing is broken there?
>
> One thing that could be taking the time is an extra roundtrip -- e.g. it
> tries to connect with ssl fails and retries without. A network trace should
> also make this obvious, and can hopefully show you exactly where in the
> connection the time is spent.
As Tom said, setting sslmode=allow or disable prevents
reconnection against hostnossl.
> psql "sslmode=disable host=127.0.0.1 dbname=postgres"
There are 4 (disable, allow, prefer, require) * 3 (host, hostssl,
hostnossl) = 12 possible combinations (ignoring veryfy-* of
sslmode) of SSL usage preferences. Among these, the following two
combinations needs reconnection.
prefer + hostnossl , allow + hostssl
Since no client can find whether a user can connect using (or not
using) SSL before making any connection, reconnection is
inevitable for the above combinations.
By the way, SSL initialization takes place only when server is
requested SSL connection (NEGOTIATE_SSL_MODE), so only prefer +
hostnossl causes the wasting SSL intialization.
Thank you for detailed info
Regards
Pavel
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center