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RE: Limit slapd memory usage on Windows?


Thanks for the quick reply!  I agree with your views on Windows and all
of our products are moving towards Linux but we have to put up with
Windows for at least a short while longer.

In case others are interested, I was able to decrease OpenLDAP's memory
usage by configuring the threads directive in slapd.conf.  Instead of
using the default (threads=16), I set threads=2.  Now we move on to the
next step - measurements to ensure that changing the threads setting
does not negatively impact performance.

Kyle Blaney


-----Original Message-----
From: openldap-software-bounces+kblaney=nortel.com@openldap.org
[mailto:openldap-software-bounces+kblaney=nortel.com@openldap.org] On
Behalf Of Howard Chu
Sent: May 28, 2008 1:30 PM
To: Blaney, Kyle (BVW:9T16)
Cc: openldap-software@openldap.org
Subject: Re: Limit slapd memory usage on Windows?

Kyle Blaney wrote:
> Is there a way to limit slapd's memory usage on Windows?  I ask 
> because we want to use OpenLDAP on memory-constrained systems. We're 
> having performance problems that occur when other applications start 
> and they need the memory used by slapd. A lot of page-swapping occurs 
> and performance suffers as a result.

It might help to build it with an alternate malloc library, instead of
using the default MSVCRT version.

In general, trying to tune anything on Windows is like trying to carve
water with a toothpick. The Windows memory manager basically does
whatever it wants, regardless. Note also that on the exact same
hardware, OpenLDAP on Linux is typically 2-3x faster than OpenLDAP on
Windows. Running a critical service on Windows is just a waste of time.

> I've tried to set a very small cachesize in slapd.conf and a very 
> small cache size in DB_CONFIG. However, those settings only decrease 
> the initial memory usage by slapd. When I add a single entry, slapd's 
> memory usage increases from 66 MB to 110 MB. When I add 100 more 
> entries, slap's memory usage increases to 276 MB. Even when I disable 
> all indexes, the memory usage is still similar. (The memory usage 
> numbers I state are the combination of slapd's private bytes and 
> virtual bytes as reported by the Windows Performance tool.) Is there 
> some way to tell slapd not to use more than X MB of memory even if 
> it's available in order to avoid future page swaps?
> Note that I'm running OpenLDAP 2.3.39 with BDB 4.4.20 on Windows XP 
> Professional with Service Pack 2.
> ---
> Kyle Blaney
> Software Engineer, System Management
> Nortel Networks

   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/