[SSSD] Memory leak with LDAP and frequent enumeration refreshes?

Dmitri Pal dpal at redhat.com
Fri Jul 6 14:05:41 UTC 2012


On 07/05/2012 10:41 PM, Mark London wrote:
> sgallagh at redhat.com wrote:
>>> Here is my solution to have a persistant uptodate local cache of all ldap entries, so as to avoid very long delays when a user issues a command that causes a large number of LDAP lookups, i.e. by doing a "ls -l /home":
>>>
>>>  enumerate = true
>>>  enum_cache_timeout = 86400 (every 24 hours)
>>>  ldap_purge_cache_timeout = 0
>>>  ldap_enumeration_refresh_timeout = 300
>>>
>>> What I would like to know, is why long delays occur when doing an "ls -l /home".  Is it because it has to write out each entry into the local database?    
>> How many users are we talking about, and are they all represented in /home?
>>
>> The initial enumeration can take up to a few minutes the first time (after that we only update on differences). Once the full enumeration has been completed, it should take about 0.02 seconds per lookup against the local cache. On ordinary lookups, there are no writes going on. Writes to the cache only occur on cache misses.
>
> "ls -l /home" is fast after enumeration.  But if I allow the enum
> cache to time out, then "ls -l /home" take minutes.  We have 430
> directories.  I get around this problem, by setting the cache timeout
> to be very long.  However, it appears that using this configuration,
> both sssd_nss and sssd_be are constantly growing in size.  I.e., here
> are the memory size after about 3 days of use.  The resident memory
> has grown from about 21m to over 200m.  The ldap refresh (every 5
> minutes), appears to be constantly adding to the cache.  Or maybe
> there is a problem with my configuration that is causing this? 
>
> 10468 root      20   0  402m 236m  14m S  0.7  1.5   2:50.74
> sssd_nss          
> 10467 root      20   0  424m 222m 8164 S  0.0  1.4  10:20.20 sssd_be
>
> Thanks. - Mark
>

Mark, is there any way we can have a full description of the use case.
Something is not right here so we would need to try to reproduce the
issue. But we need a good overview of what is going on in your case and
how things are configured. I know you provided big pieces of this
information across multiple emails. Can you please consolidate it into
one report and open a trac ticket or BZ? 

>
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-- 
Thank you,
Dmitri Pal

Sr. Engineering Manager IPA project,
Red Hat Inc.


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