On Fri, Dec 08, 2017 at 11:57:23AM +0100, Franky Van Liedekerke wrote:
> Op Vrijdag, 08-12-2017 om 11:34 schreef Sumit Bose:
> > On Fri, Dec 08, 2017 at 11:10:49AM +0100, Franky Van Liedekerke wrote:
> > > Before opening a bug report, I wanted to discuss a new issue here. 
> > > 
> > > I have ldap users that are in 1500 groups (yeah, I know ... not my choice 
> > > either), ldap is using rfc2307 scheme (openldap, redhat EL7).
> > > Now, when connecting sssd to this ldap server, I've already set 
> > > enumeration=false, and also ignore_group_members=true (performance ...).
> > > However, with ignore_group_members=true, I'm getting this in the 
> > > sssd_nss.log when doing a 'groups <userid>" command:
> > > 
> > > [sssd[nss]] [sss_mc_find_record] (0x0010): Corrupted fastcache. name_ptr 
> > > value is 16
> > > 
> > > (once when the cache is empty, and after that once or twice per 
> > > groups-request).
> > > I also see this in /var/log/messages (related of course):
> > > 
> > > sssd[nss]: Stored copy of corrupted mmap cache in file 
> > > '/var/lib/sss/mc/group_corrupted#012'
> > > 
> > > As a result, this prevents the use of the sssd fast cache, so group 
> > > requests at best take 5.5 seconds.
> > > Now this problem happens 95% of the cases (which leads me to believe it 
> > > is a timing bug), but when I set ignore_group_members=false, this is not 
> > > happening (and when groups are ok in the fast cache: 0,03 secs response 
> > > time).
> > > 
> > > Ideas? Hints? Or should I just go and open a bug report? Is there a real 
> > > performance drawback to setting ignore_group_members=false?
> > 
> > There is already a BZ
> > https://bugzilla.redhat.com/show_bug.cgi?id=1490120.
> > 
> > I think in your setup (plain LDAP with rfc2307) the performance loss
> > when using ignore_group_members=false (the default) should be
> > acceptable.
> > 
> > bye,
> > Sumit
> 
> Unfortunately I can't view the content of that BZ (no access, I'm searching 
> for an account at my current company that does), so any insight/summary on 
> that one would be appreciated.

Here is the related upstream ticket
https://pagure.io/SSSD/sssd/issue/3571.

> Fun fact just for info: we had to switch to rfc2307 (from 2307bis) because of 
> another bug in sssd that ignores the setting to not do nested group searches, 
> which resulted in a huge amount of extra ldap searches per user (1 per group).

Did you open a ticket about this?

bye,
Sumit

> 
> Franky
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