[Freeipa-devel] slow response

Wed Aug 1 15:20:10 UTC 2012

El mié, 01-08-2012 a las 10:35 -0400, Simo Sorce escribió:
> On Tue, 2012-07-31 at 08:49 -0700, Stephen Ingram wrote:
> > On Tue, Jul 31, 2012 at 1:39 AM, Petr Spacek <pspacek at redhat.com> wrote:
> > > On 07/31/2012 12:27 AM, John Dennis wrote:
> > >>
> > >>
> > >> What is taking so long with session bookkeeping? I don't know yet. I would
> > >> need more timing instrumentation. I will say when I looked at the
> > >> python-krb5
> > >> code (which we use to populate the ccache from the session and read back
> > >> to
> > >> store in the session) seemed to be remarkably inefficient. We also elected
> > >> to
> > >> use file based ccache rather than in-memory ccache (that means there is a
> > >> bit
> > >> of file-IO occurring).
> > >
> > >
> > > A note regarding python-krbV:
> > > I used python-krbV extensively in my thesis for KDC stress test. Python-krbV
> > > can obtain several thousands of TGTs per second (even with ccache in a
> > > file). AFAIK VFS calls are not done synchronously. But others parts of
> > > python-krbV were left uncovered, so it can contain some surprises.
> > >
> > > === Wild speculation follows ===
> > > 1.5 second is incredibly long time, it sounds like some kind of timeout.
> > > Krb5 libs have usual timeout = 1 second per request.
> > >
> > > Are all KDCs in /etc/krb5.conf alive and reachable?
> > 
> > In this case, as I'm referring to the extreme slowness of the Web UI,
> > the KDC is on the same system (the ipa server) that is making the
> > request, correct?
> > 
> > > Is SSSD running on problematic server?
> > 
> > Yes. Again, I'm guessing the problematic server is the IPA server itself.
> > 
> > > Is proper KDC selected by SSSD KDC auto-locator plugin?
> > > (See /var/lib/sss/pubconf/)
> > 
> > Yes, I checked that file and it is the IP address of the IPA server on
> > the same server. Perhaps should this be 127.0.0.1 instead?
> > 
> > I also have checked the resolv.conf file, and indeed the IP points to
> > the IPA server itself (same machine) as expected. Both forward and
> > reverse DNS work. I'm not really sure what else could be setup
> > incorrectly to cause any KDC slowness.
> > 
> > Due to the extreme UI slowness issue, I have not created any replicas
> > so this system is it. I'm not so sure I would be able to see the 1.5 s
> > delay if it weren't compounded by the overall slowness of the Web UI,
> > however, the KDC seems to perform well for other systems in the realm.
> > I'm certainly not taxing it with a huge load, but tickets seem to be
> > issued without delay.
> 
> Stephen,
> another user sent me a wireshark trace for a similar performance issue.
> So far I see a pause when doing the first leg of a SASL authentication.
> This may well explain also your issue.

Hi, I experience the same delay in SASL authentication. The number I
posted on freeipa-users, show a 1-2 second delay with SASL
authentication:

# time ldapsearch -x uid=bdteg01662 dn
# extended LDIF
#
# LDAPv3
# base <dc=xxx,dc=gob,dc=ve> (default) with scope subtree
# filter: uid=bdteg01662
# requesting: dn 
#

# bdteg01662, users, accounts, xxx.gob.ve
dn: uid=bdteg01662,cn=users,cn=accounts,dc=xxx,dc=gob,dc=ve

# search result
search: 2
result: 0 Success

# numResponses: 2
# numEntries: 1

real    0m0.006s
user    0m0.001s
sys     0m0.003s

# time ldapsearch -Y GSSAPI uid=bdteg01662 dn
SASL/GSSAPI authentication started
SASL username: admin at XXX.GOB.VE
SASL SSF: 56
SASL data security layer installed.
# extended LDIF
#
# LDAPv3
# base <dc=xxx,dc=gob,dc=ve> (default) with scope subtree
# filter: uid=bdteg01662
# requesting: dn 
#

# bdteg01662, users, accounts, xxx.gob.ve
dn: uid=bdteg01662,cn=users,cn=accounts,dc=xxx,dc=gob,dc=ve

# search result
search: 4
result: 0 Success

# numResponses: 2
# numEntries: 1

real    0m2.344s
user    0m0.007s
sys     0m0.005s

> Can you test connecting to the ldap server using ldapsearch -Y GSSAPI
> (you need a kerberos ticket) and telling me if you experience any
> delay ?
> If you could run a bunch of searches in a loop and take a wireshark
> trace that may help analyzing the timings and seeing if there is a
> correlation.
> 
> Simo.
> 

-- 
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