Re: understanding memory issues

"W.C.A. Wijngaards" <[email protected]> Mon, 2 Jul 2018 15:26:27 +0200
Newsgroups	gmane.network.dns.nsd.general
Message-ID	<[email protected]>
Hi Klaus,

On 02/07/18 15:24, W.C.A. Wijngaards wrote:
> Hi Klaus,
> 
> On 02/07/18 15:01, Klaus Darilion wrote:
>> Hi!
>>
>> We use NSD 4.1.6 as slave for a large zone (2G zone file). It seems
>> sometimes the memory is too short:
> 
> NSD tries to recover from the cannot allocate memory failure by
> performing the update again.  But I guess this also fails (for the same
> reason?).  Linux has kernel settings on memory overcommit that allow you
> to bypass these limits; since NSD shares most of the memory, also after
> fork, and this is not the default assumption of the virtual memory
> overcommit heuristic.  But you don't really need to set it I think,
> because you can save memory with database: "" and by upgrading.
> 
> With NSD 4.1.6 in use one solution is update to the latest, 4.1.22.  Set
> database: "" in nsd.conf, that saves about half memory.  Then with the
> version upgrade, you can save half memory again on that result, by
> --enable-packed at compile time and the selective nsec3 allocations.

Oh and I missed that in 4.1.13 introduced another 15% memory savings
with the --disable-radix-tree configure option.  You can use that option
on top of the previous options.  I guess that is likely to solve the
fork failed: cannot allocate memory error.

Best regards, Wouter

> 
> Best regards, Wouter
> 
>>
>> 03:44:19 nsd[16836]: xfrd: zone xx committed "received update to serial
>> 2018063010 at 2018-06-30T03:44:19 from 2a02:850:9::5 TSIG verified with
>> key rcode0-distribution"
>> 03:45:30 nsd[16837]: rehash of zone xx. with parameters 1 0 5
>> 6a0bf229ad0c7a2a
>> 03:45:39 nsd[16837]: nsec3 xx 1 %
>> 03:46:29 nsd[16837]: zone xx. received update to serial 2018063010 at
>> 2018-06-30T03:44:19 from 2a02:850:9::5 TSIG verified with key rcode0-xxx
>> of 1717205965 bytes in 324.657 seconds
>> 03:46:29 nsd[16837]: fork failed: Cannot allocate memory
>> 03:46:32 nsd[16836]: process 16837 exited with status 256
>> 03:46:32 nsd[7188]: handle_reload_cmd: reload closed cmd channel
>> 03:46:32 nsd[7188]: Reload process 16837 failed, continuing with old
>> database
>> 03:46:32 nsd[16836]: zone xx serial 2018063009 is updated to 2018063010.
>>
>>
>> What confuses me is that since above error all following attemtps to
>> transfer and activate the new zone fails, but without any reason.
>>
>>
>> 03:51:50 nsd[16836]: xfrd: zone xx committed "received update to serial
>> 2018063011 at 2018-06-30T03:51:50 from 2a02:850:9::5 TSIG verified with
>> key rcode0-xxx"
>> 03:51:58 nsd[16836]: xfrd: zone xx: soa serial 2018063011 update failed,
>> restarting transfer (notified zone)
>> 03:56:05 nsd[16836]: xfrd: zone xx committed "received update to serial
>> 2018063011 at 2018-06-30T03:56:05 from 2a02:850:9::5 TSIG verified with
>> key rcode0-xxx"
>> 03:56:18 nsd[16836]: xfrd: zone xx: soa serial 2018063011 update failed,
>> restarting transfer (notified zone)
>>
>>
>> Any idea why NSD is not logging the cause of the "update failed"? I
>> guess it is also memory related, or does NSD just not recover from the
>> initial "Cannot allocate memory"?
>>
>> Thanks
>> Klaus
>> _______________________________________________
>> nsd-users mailing list
>> [email protected]
>> https://open.nlnetlabs.nl/mailman/listinfo/nsd-users
>>
> 
> 
> 
> 
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