[Pdns-users] Possible tcp listener issue

Brad Dameron Brad.Dameron at clearwire.com
Tue Jun 29 05:55:07 UTC 2010

> -----Original Message-----
> So far, Josh & Simon are the only ones reporting this issue though, so
> something must be going on. What Laurent Papier reported has been
> already (although he may not know it yet ;-))
> 	Bert


Us too!!

We're able to reproduce what may be this same TCP listener issue that is
being discussed on the email list with little effort, using the latest
3.3 pre-release code.
We use the queryfile-example-3million file from nominum :
and the script below to fire off a flood of TCP requests, 1000 at a
Within a few minutes, pdns_recursor locks up and refuses to answer any
more TCP queries. UDP continues fine. Our last run, it queried only 16K
addresses before hanging.
Environment is a HP G6 blade running CentOS 5.1 Linux: 
# uname -a
Linux MOC-LAB001-HPB-DNS-NTP-1 2.6.18-53.1.14.el5 #1 SMP Wed Mar 5
11:37:38 EST 2008 x86_64 x86_64 x86_64 GNU/Linux
Invoked with the following arguments: 
/usr/sbin/pdns_recursor --local-address=,
--allow-from= --max-cache-entries=3000000 --log-common-errors=no
--threads=4 --socket-dir=/var/run/recursor1 --daemon --dont-query=


integer n=0
zcat queryfile-example-3million.gz | while read x ; do
	let n=n+1
	if [ $n -le $MAX ] ; then
		print "dig @ +tcp +short $x >> out 2>>out.err
		print "wait"
		let n=0;

#	genrun.sh > run
#	sh ./run &
# Use the following script to monitor progress:
#	#!/bin/ksh
#	while : ; do
#		nt=$(rec_control --socket-dir=/var/run/recursor1 get
#		nl=$(netstat -an|grep :53|grep -v LISTEN|wc -l)
#		print "$nt queries $nl open"
#		sleep 5
#	done

These errors were noted in the logs:

pdns_recursor[28030]: segfault at 00007ffefffffff8 rip 0000000000455740
rsp 00002aaaaaaecbb0 error 4
pdns_recursor[28082] general protection rip:455740 rsp:2aaaaaaecbb0

Let us know if you have any new patches to test!


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