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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">So, when a zone gets updated, PowerDNS checks if it has to notify slaves and send NOTIFYs to the slaves. Once this is done, it updates
the notified_serial in the domains table. This UPDATE, for whatever reason, causes a deadlock.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Maybe you can work around that problem. You mentioned that you use DB replication. So, if all the slaves get their zones via DB replication
and NOT via NOTIFY/AXFR, then you can disable the NOTIFYs and "UPDATE notified_serial...." query by setting master=no in pdns.conf.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">So, if Powerdns need not send NOTIFYs, then set master=no.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Klaus<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="DE" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Von:</span></b><span lang="DE" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Pdns-users <pdns-users-bounces@mailman.powerdns.com>
<b>Im Auftrag von </b>Klaus Darilion via Pdns-users<br>
<b>Gesendet:</b> Freitag, 18. Februar 2022 09:58<br>
<b>An:</b> Riccardo Brunetti <riccardo.brunetti@host.it>; Pdns-users@mailman.powerdns.com<br>
<b>Betreff:</b> Re: [Pdns-users] powerdns frequently crashes and restarts<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Look in the mysql-server log. Maybe it mentions which other transaction causes the deadlock. That my help to find the cause.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Is this problem something new? I.e. started it after a PDNs or Mysql Upgrade?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Klaus<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="DE" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Von:</span></b><span lang="DE" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Pdns-users <<a href="mailto:pdns-users-bounces@mailman.powerdns.com">pdns-users-bounces@mailman.powerdns.com</a>>
<b>Im Auftrag von </b>Riccardo Brunetti via Pdns-users<br>
<b>Gesendet:</b> Freitag, 18. Februar 2022 09:55<br>
<b>An:</b> <a href="mailto:pdns-users@mailman.powerdns.com">pdns-users@mailman.powerdns.com</a><br>
<b>Betreff:</b> [Pdns-users] powerdns frequently crashes and restarts<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Hello.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">We are having quite frequent crashes of our pdns server with the following syslog messages:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:33 xxxx.xxxxx.xxx.xxxx pdns_server[26672]: Exiting because communicator thread died with error: GSQLBackend unable to refresh domain_id XXXXX: Could not execute mysql statement: update
domains set notified_serial=? where id=?: Deadlock found when trying to get lock; try restarting transaction<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:34 xxxx.xxxxx.xxx.xxxx systemd[1]: pdns.service: main process exited, code=exited, status=1/FAILURE<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:34 xxxx.xxxxx.xxx.xxxx systemd[1]: Unit pdns.service entered failed state.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:34 xxxx.xxxxx.xxx.xxxx systemd[1]: pdns.service failed.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:35 xxxx.xxxxx.xxx.xxxx systemd[1]: pdns.service holdoff time over, scheduling restart.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:35 xxxx.xxxxx.xxx.xxxx systemd[1]: Stopped PowerDNS Authoritative Server.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:35 xxxx.xxxxx.xxx.xxxx systemd[1]: Starting PowerDNS Authoritative Server...<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:35 xxxx.xxxxx.xxx.xxxx pdns_server[25899]: Loading '/usr/lib64/pdns/libgmysqlbackend.so'<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:35 xxxx.xxxxx.xxx.xxxx pdns_server[25899]: This is a standalone pdns<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">I don't know if this can be related, but just before those crashes we see messages like:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Feb 17 13:39:32 xxxx.xxxxx.xxx.xxxx pdns_server[26672]: Request to queue notification for domain yyyyy.yy was processed, but no valid nameserver or ALSO-NOTIFYs found. Not notifying!<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Just to mention briefly our setup: we are running:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">PowerDNS Authoritative Server 4.5.2 (C)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">in a percona mysql cluster with three nodes, each node having it's own mysql and pdns server (in order to have redundancy of database and APIs).<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">This cluster acts as a "backend master" for the real authoritative slaves, placed elsewhere, replicating the db.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Can you help us to understand why we have those crashes?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Thanks<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Riccardo<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"> <o:p></o:p></span></p>
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