[Pdns-users] PowerDNS Auth is slow on control socket

[Chris Hofstaedtler]

Hi,

> On 05.01.2018, at 10:44, Klaus Darilion <klaus.mailinglists at pernau.at> wrote:
> [..]

> I analyzed the problem with tcpdump and following happens:
> 
> * pdns_control established the TCP connection
> * pdns_control sends the secret and the command
> * 7 seconds later pdns_control gives up waiting and closes the TCP
> conenction (FIN)
> * another 1 second later the server responses with "Added retrieval
> request ...."
> 
> Hence, the problem is that PowerDNS is sometimes very slow adding the
> retrieval request.
> 
> Do you have an idea why this happens? Are there some internal locks? Any
> ideas how to debug this to find the problem for the slow reaction?

I don’t have a good idea, but a few things to consider:

1) tcp control socket is single threaded. if you have lots of
concurrency there, you’ll see issues

2) the database lookup for the zone is done on the same thread.

Debugging guesses:

for 1) see if pdns passed the accept() call.
for 2) break on DLNotifyRetrieveHandler

Good luck,
Chris

-- 
Chris Hofstaedtler / Deduktiva GmbH (FN 418592 b, HG Wien)
www.deduktiva.com / +43 1 353 1707