[Unbound-users] segfault when using dnstap at high load
writeme at rogeriobastos.eti.br
Wed Apr 8 12:23:42 UTC 2015
I appreciate you help.
On 2015-04-08 00:43, Robert Edmonds wrote:
> Hi, Rogerio:
> Thanks for these details, I can easily spin up a dual core amd64 VM
> running Debian jessie soon and try to replicate the problem.
> Do you get a segfault immediately, or does it only occur after running
> for some time under load?
segfault occur after some time.
> Can you try testing with "num-threads: 1"? (This will still result in
> multiple threads running in the Unbound process, but the dnstap I/O
> thread will only be consuming data from a single worker thread.)
I get the same error with "num-threads: 1".
> Also, can you compile your unbound package with debugging symbols and
> obtain a backtrace from a crash? You should be able to build a
> debugging enabled package with:
> DEB_BUILD_OPTIONS='nostrip debug' dpkg-buildpackage -b -uc -us
> Then, run "gdb --args unbound -d" until it crashes, and at the gdb
> prompt run:
> thread apply all bt full
The output is attached.
> Rogerio Bastos wrote:
>> 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
>> >>enabled in configuration.
>> >>I am using the debian package (version 1.5.3) avaible in  and
>> >>with dnstap enabled.
>> >>I'm following instruction descripted in  and using fstrm version
>> >>To test the server, I'm using dnsblast  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
>> >Can you show the "dnstap:" block of settings from your config, and the
>> >"num-threads" server setting?
>> I'm using optimisation settings based on  (the Debian version is
>> 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 :
>> 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.
>>  https://www.unbound.net/documentation/howto_optimise.html
>>  http://dnstap.info/Examples/
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