[nsd-users] Assumed Memory Leak in NSD-3.2.3 ??

Fri Apr 9 08:58:12 UTC 2010

Hello,

we ( the DENIC eG ) are using your nameserver software NSD now for several 
years.
After  switching to NSD-3.2.3  we are getting trouble with the memory 
footprint of NSD-3.2.3.
The memory  consumtion is raising until its physical  limit ist reached, 
then swap is used.
 After all limits are reached NSD-3.2.3 can't  start an ixfr  anymore.

It looks like if swapped memory is not freed.
Starting NSD with one process, NSD forks a second process as usual. 
Then another process is opened. beeing independent from the others.
I assume the forked process is used to perform the ixfr.
I don't know the purpose of the independent process. 

We run our servers on Xen virtual machines using 12 GB of RAM and 10 GB 
Swap.
The size of our zonefile is about 1.1 GB.
What size of RAM and swao do you recommend  for a zonefile of this size ?
In the past, using  NSD-2.1.4,  a RAM size of  8 GB had been sufficient.

Here an output of top of our server after a fresh start:

top - 15:14:33 up 50 days,  3:15,  2 users,  load average: 0.00, 0.23, 
0.34
Tasks:  61 total,   1 running,  60 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si, 
0.0%st
Mem:  12582912k total,  6505944k used,  6076968k free,     1088k buffers
Swap:  9999992k total,   689732k used,  9310260k free,     8348k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
20616 dnsadm    15   0 86632 1612  912 S    0  0.0   0:00.00 sshd
20617 dnsadm    15   0 67276 1988  988 S    0  0.0   0:00.01 tcsh
20909 dnsadm    15   0 63536  992  836 S    0  0.0   0:00.00 less
21936 dnsadm    15   0 86628 1608  912 S    0  0.0   0:00.00 sshd
21937 dnsadm    15   0 67268 1984  988 S    0  0.0   0:00.02 tcsh
22259 dnsadm    15   0 10704  992  776 R    0  0.0   0:00.15 top
22273 dnsadm    16   0 3282m 2.6g  608 S    0 21.3   0:14.30 nsd
22284 dnsadm    15   0 3439m 3.3g  412 S    0 27.7   5:40.85 nsd
22526 dnsadm    18   0 3439m 3.3g  136 S    0 27.7   0:00.00 nsd

Here the output of top  approx. 1 week of running:

top - 14:53:59 up 50 days,  2:54,  2 users,  load average: 0.00, 0.00, 
0.00
Tasks:  61 total,   2 running,  59 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si, 
0.0%st
Mem:  12582912k total,  9097360k used,  3485552k free,    94196k buffers
Swap:  9999992k total,  2720028k used,  7279964k free,  1953724k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
19608 dnsadm    15   0 5758m 5.6g  340 S    0 46.5   0:00.84 nsd
19609 dnsadm    18   0 5758m 5.6g  136 S    0 46.5   0:00.00 nsd
20197 dnsadm    15   0 3282m 704m  616 S    0  5.7   0:14.68 nsd
20616 dnsadm    15   0 86632 1624  912 S    0  0.0   0:00.00 sshd
20617 dnsadm    15   0 67276 1988  988 S    0  0.0   0:00.01 tcsh
20909 dnsadm    15   0 63536  992  836 S    0  0.0   0:00.00 less
21936 dnsadm    16   0 86628 1616  912 R    0  0.0   0:00.00 sshd
21937 dnsadm    15   0 67268 1984  988 S    0  0.0   0:00.02 tcsh
21970 dnsadm    15   0 10704  992  776 R    0  0.0   0:00.00 top

As You can see, NSD is using a lot of RAM space.
The longer NSD is running the more memory is allocated until the limit is 
reached having the famous oom-killer (out of memory) inside the kernel 
killing some process.

There seems to be a memory leak somewhere.

Can you assist us with this problem ?

Thank you very much..

kind regards

-- 
Christian Petrasch 
IT-Services

DENIC eG
Kaiserstraße 75-77
60329 Frankfurt am Main
GERMANY

E-Mail: petrasch at denic.de
Fon: +49 69 27235-429
Fax: +49 69 27235-239
http://www.denic.de

PGP-KeyID: 17613DFA, Fingerprint: 791A 40DF 47EF DBBD D8E3 72D0 9A6A 846E 
1761 3DFA

Angaben nach § 25a Absatz 1 GenG:
DENIC Domain Verwaltungs- und Betriebsgesellschaft eG (Sitz: Frankfurt am 
Main)
Vorstand: Sabine Dolderer, Marcus Schäfer, Carsten Schiefner, Dr. Jörg 
Schweiger 
Vorsitzender des Aufsichtsrats: Elmar Knipp
Eingetragen unter Nr. 770 im Genossenschaftsregister, Amtsgericht 
Frankfurt am Main
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.nlnetlabs.nl/pipermail/nsd-users/attachments/20100409/09fbffc6/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 6784 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://lists.nlnetlabs.nl/pipermail/nsd-users/attachments/20100409/09fbffc6/attachment.bin>