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

Fabio Sangiovanni sangiovanni at nweb.it
Mon Jan 2 17:05:02 UTC 2012

Hi Bert,

are you planning to run multiple Lua sessions per thread in the future (in PowerDNS Recursor)?
If yes, do you think it will be possible to have a switch for this feature in recursor.conf?
I need to make a decision for my company about the use of PowerDNS Recursor in a project and everything depends on the possibility of having one single lua session per thread.

Thanks a lot for your support.


Il giorno 30/dic/2011, alle ore 09:43, bert hubert ha scritto:

> 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!
> 	Bert

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