[Pdns-users] pdns-recursor: Only two threads used when threads=4

Øystein Viggen oystein.viggen at ntnu.no
Fri Oct 21 07:45:58 UTC 2016

Grace Wang <xiaohong.grace.wang at gmail.com> writes:

>> I installed pdns-recursor 4.0.3 on a CentOS 6.5 box, that has 20 physical
>> cores and 128G RAM. When I set the threads in /etc/pdns-recursor/
>> recursor.conf to be 4 or 12, then issued tons of queries (one query sent
>> multiple times using multiple dnsperf instances simultaneously) at it, I
>> noticed only 2 of the threads were working actively, each using almost 100%
>> CPU and ~90% CPU, respectively. The other threads were using 0% CPU.

Could it be that pdns-recursor isn't optimized very well for serving the
same same query at a very high rate?

With about 2000 queries/second of real-world DNS traffic from servers
and users, I'm seeing a good spread of the load over 24 threads on
pdns-recursor 4.0.3.  (Ubuntu 16.04, if that matters).


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