[Unbound-users] segfault when using dnstap at high load
edmonds at debian.org
Wed Apr 8 03:43:32 UTC 2015
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?
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.)
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
thread apply all bt full
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 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 :
> 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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edmonds at debian.org
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