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Re: OpenLDAP Memory Usage

In regard to: Re: OpenLDAP Memory Usage, Quanah Gibson-Mount said (at...:
--On Friday, March 18, 2011 6:29 PM -0500 Tim Mooney <Tim.Mooney@ndsu.edu> wrote: 


In regard to: Re: OpenLDAP Memory Usage, Quanah Gibson-Mount said (at...:


--On Thursday, March 17, 2011 8:06 AM -0700 Howard Chu <hyc@symas.com>
wrote:



This is a relatively high-volume environment, with 4 servers running
with mirrormode to enable multi-master replication. The current
database size is about 900mb. Is there any setting that could limit
this memory usage? I don't feel this is "normal" considering our DB
size and cache sizes.


Very likely ITS#6660, you need to update to 2.4.24.


Also make sure you use an alternative memory allocator if you are
running on  Linux, such as tcmalloc from the google perf tools package,
or hoard.


Can you expound a bit more on that, Quanah, or point me at some more
complete information on why using a non-default memory allocator is
beneficial for OpenLDAP on Linux?

I've been subscribed to the OpenLDAP devel and now technical mailing list
for quite a while and I don't recall seeing anything stated in such strong
terms about not using the default malloc/free on Linux.


It's been discussed in detail several times, but not for a few years.

I suggest reading over:

<http://www.openldap.org/pub/hyc/scale2007.pdf>


Thanks Quanah, that was very helpful.  Slides 23 and 33-35 (comparing
the various memory allocators) were very useful, especially when coupled
with the openldap-devel threads starting on August 24 2006.

I also found slide 26, about the problem with trying to benchmark OpenLDAP
using slow bench mark tools, interesting.  What tools are recommended
these days, for benchmarking an OpenLDAP installation?  The most promising
ones I could find were SLAMD (which was panned in slide 26) and cbe4.
Are there others that are noteworthy?

Thanks again,

Tim
--
Tim Mooney                                  mooney@dogbert.cc.ndsu.NoDak.edu
Enterprise Computing & Infrastructure       701-231-1076 (Voice)
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