Hi Klaus, I excluded network issues for a while, so I focused my analysis on MySQL.
Simply running a 'show processlist' during one of the random timeouts brought me to the solution: I found a lot of queries in state 'Waiting for query cache lock', so I completely disabled query_cache in MySQL configuration. I made the change on Sep 19th, and never had a timeout since then. I hope this can be useful for anyone experiencing the same issue. Best, -- Federico Chiacchiaretta System Administrator Netsons S.r.l. - https://www.netsons.com On Thu, 2019-09-26 at 07:23 +0200, Klaus Darilion wrote: > I think, first you should find out if there is a problem with > PowerDNS > or the network - or inbetween. > > If this happens regularly, just use tcpdump to caputre all DNS > traffic > to a file (rotate files, keep only X files and choose X to not fill > your > complete hard disk). > > Or even simpler - just capture with tcpdump the loopback traffic > (your > own check script) with -i lo. > > Make sure you really see the requests to PDNS, but no answers. Of > maybe > there are answers, but much too late. > > The problem may be that PDNS reads fromt he socket to sloow. Then > the > socket fills up and you have packet loss (tools like netstat can > report > this). > > Also monitor the PDNS statistics. Ie read: > https://blog.powerdns.com/2014/12/11/powerdns-graphing-as-a-service/ > > Then watch the number of outstanding queries, maybe send them every > second. > > regards > Klaus _______________________________________________ Pdns-users mailing list Pdns-users@mailman.powerdns.com https://mailman.powerdns.com/mailman/listinfo/pdns-users
