[Unbound-users] segfault when using dnstap at high load

Rogerio Bastos writeme at rogeriobastos.eti.br
Tue Apr 7 11:46:51 UTC 2015

On 2015-04-06 22:44, Robert Edmonds wrote:
> Rogerio Bastos wrote:
>> I'm trying to test unbound witk dnstap. It works fine with low load, 
>> but
>> exists with segfault at high load. The segfault only happens when 
>> dnstap is
>> enabled in configuration.
>> I am using the debian package (version 1.5.3) avaible in [1] and 
>> recompiled
>> with dnstap enabled.
>> I'm following instruction descripted in [2] and using fstrm version 
>> 0.2.0.
>> To test the server, I'm using dnsblast [3] with the follow command:
>> ./dnsblast <server address> 50000 500
> Hi, Rogerio:
> Sorry to hear that.  I would be happy to help debug dnstap (I wrote the
> dnstap patchset for Unbound).  Can I get some information about your
> environment?
> Can you show the "dnstap:" block of settings from your config, and the
> "num-threads" server setting?

I'm using optimisation settings based on [1] (the Debian version is 
compiled with libevent):

     num-threads: 2

     msg-cache-slabs: 2
     rrset-cache-slabs: 2
     infra-cache-slabs: 2
     key-cache-slabs: 2

     rrset-cache-size: 100m
     msg-cache-size: 50m

     outgoing-range: 8192
     num-queries-per-thread: 4096

     so-rcvbuf: 4m
     so-sndbuf: 4m

I'm using the example from dnstap's site [2]:

     dnstap-enable: yes
     dnstap-socket-path: "/var/run/unbound/dnstap.sock"
     dnstap-send-identity: yes
     dnstap-send-version: yes
     dnstap-log-resolver-response-messages: yes
     dnstap-log-client-query-messages: yes

> Does fstrm's "make check" test suite succeed?

Yes, all tests is ok.

> What version of protobuf-c are you using?  (Did you compile from 
> source,
> or did you use a packaged version?)

The packaged version from Debian Jessie (version 1.0.2).

> What OS version are you using?  (Based on your mention of the Debian
> package from experimental, I would guess Debian or Ubuntu.)

Debian Jessie, the next-stable version.

> Are you using a uniprocessor or SMP machine?  Also, since there are 
> some
> architecture-specific parts in fstrm, what architecture are you using?

I'm using a amd64 virtual machine with a two core CPU.

[1] https://www.unbound.net/documentation/howto_optimise.html
[2] http://dnstap.info/Examples/


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