[Pdns-users] pdns_control hangs

Vincent Hoffman vince at unsane.co.uk
Mon Jan 7 15:56:37 UTC 2013

    We are using powerdns pdns-server-3.1 on centos 6 x86_64 with the
mydns backend and so far its been working well.
However 3 or 4 times now our statistics gathered by munin seem to have
stopped working, each time when this happens pdns_control just hangs
when run with an argument leaving us with many many instances of it
running. The server itself is unaffected but we lose visibility and the
overhead of the many running pdns_controlprocesses could become an issue
eventually. running strace on pdns_control ping hangs at
open("/etc/powerdns/pdns.conf", O_RDONLY) = 3
read(3, "out-of-zone-additional-processin"..., 8191) = 525
read(3, "", 8191)                       = 0
close(3)                                = 0
socket(PF_FILE, SOCK_STREAM, 0)         = 3
fcntl(3, F_GETFD)                       = 0
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
open("/tmp/lsockcS1QOa", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
unlink("/tmp/lsockcS1QOa")              = 0
bind(3, {sa_family=AF_FILE, path="/tmp/lsockcS1QOa"}, 110) = 0
chmod("/tmp/lsockcS1QOa", 0666)         = 0
connect(3, {sa_family=AF_FILE,
path="/var/run/pdns-server/pdns.controlsocket"}, 110

Where it will sit indefinitely.
As far as I can see this socket is still held open by the server
[root at delphi ~]# lsof | grep pdns.controlsocket
pdns_serv  4103 powerdns    5u     unix 0xffff8801b2a5d980       0t0  
27934168 /var/run/pdns-server/pdns.controlsocket
pdns_serv 10652     root    4u     unix 0xffff8801283fa980       0t0  
22727451 /var/run/pdns-server/pdns.controlsocket
pdns_serv 10652     root    5u     unix 0xffff8801b2a5d980       0t0  
27934168 /var/run/pdns-server/pdns.controlsocket

and is accessible
[root at delphi ~]# ls -la /var/run/pdns-server/pdns.controlsocket
srw-rw---- 1 root powerdns 0 Dec 10 12:03

any suggestions on why this would be happening and how to prevent it?


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