feedback on ldap improvement in samba 4.11

Gary Lockyer gary at
Tue Nov 19 20:10:07 UTC 2019

Yeah still a little reluctant about having processes ignoring SIGKILL,
but given that we use the control pipes to shut down it should probably
be ok.  It's just going to require a bit of thought to make sure things
can be shut down.

Ngā mihi
On 20/11/19 08:53, Andrew Bartlett via samba-technical wrote:
> On Wed, 2019-11-13 at 11:24 +0100, Denis Cardon via samba-technical
> wrote:
>> Hi everyone,
>> I just wanted to say how impressed I was with the improvement in
>> memory 
>> handling in ldap server in samba 4.11 that were announced in the
>> changelog.
>> I was doing some debug on OOMKiller issues on a Samba-AD 4.9 with a 
>> large database in production. There are some buggy softwares that
>> make 
>> queries for all users (the most peculiar one I have seen is a print 
>> driver...) and Samba 4.9 properly handles the query but allocate
>> around 
>> 2GiB RAM for the query while the client downloads the result. With a 
>> handfull of such queries piling up it can quickly run the server out
>> of 
>> memory.
>> On the other hand with Samba-4.11 memory is allocated in a much more 
>> frugal way and it can handle hundred of such buggy queries without 
>> crashing (it may be slow but it does not crash). So kudos the
>> Catalyst 
>> dev team for that great piece of work!
> Thank you so much!  This work started long, long ago when Simo (at the
> time controversially) made ldb async, so it was really nice to be able
> to finish the job and see the end result finally show in something so
> valuable. 
> When we did it, we were not sure that it would help outside our
> synthetic benchmarks, so to hear the difference it makes in the real
> world is wonderful!
>> About the prefork model, the master ldap process is properly
>> restarting 
>> the child process after a SIGTERM but it is not restarting after a 
>> SIGKILL. Is it normal?
> I get Gary's view about a manual kill -9 respawing perhaps being
> unwanted, but I agree, a re-spawn system that doesn't cope with the OOM
> killer is less than ideal, I would have expected such a process to be
> restarted (perhaps after a bit longer wait). 
> Andrew Bartlett

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