[Pdns-users] pdns recursor - unthreaded vs threaded operation

bert hubert bert.hubert at netherlabs.nl
Fri Dec 30 08:43:34 UTC 2011

On Thu, Dec 29, 2011 at 08:55:57AM +0000, Fabio Sangiovanni wrote:
> am I right thinking this would solve my problem?

For now, and for this version of the PowerDNS Recursor, if you set threads
to 1, you will really only get 1 simultaneous Lua session.

However, this is not true in other parts of PowerDNS. In the authoritative
server if you set 'distributor-threads=1' you might still get several
parallel database connections. 

If you are going to do synchronous SQL updates from Lua, do realize that these
typically cost up to a millisecond including latency.

This means that your Resolver will peak at 1000 qps.

> how deep is the impact on performances changing the number of threads from
> 2 (default setting) to just 1?  are there other sensible settings that I
> could adjust to better suit my needs?

You might want to look at other ways of doing statistics if you truly want
high performance.

PowerDNS right now does not offer a good interface for very rapid query
logging, but perhaps you could use a textfile from Lua.

Good luck!


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