[collectd] Bug#535787: collectd: powerdns monitoring hangs on the pdns socket (pdns 2.9.22)

[Florian Forster]

On Sat, Jul 04, 2009 at 08:29:49PM -0600, thomas morgan wrote:
> Package: collectd
> Version: 4.6.3-1~bpo50+1
[…]
> There is some kind of incompatibility between collectd and powerdns
> 2.9.22. With powerdns support enabled in collectd, collectd connects
> to powerdns's unix socket. The connection hangs indefinitely.
[…]
> collectd will no longer even shutdown and must be kill -9'd. It render
> powerdns's control socket useless as well, so it can no longer be
> managed either (until collectd is killed). 
> 
> Things work as expected with powerdns 2.9.21.2. I tried collectd 4.6.2
> also, with the same problem.

The two connection types, “Server” and “Recursor”, actually result in
different types of sockets. With “Server” the UNIX socket is used in
STREAM mode (think: TCP). In this mode, the plugin will issue the
  SHOW *
command to the PowerDNS plugin and then read back all the data the
server is sending back. The appropriate function returns when the server
(PowerDNS) closes the connection.

I'd check if this is the case. Maybe the PowerDNS folks decided that
it'd be a nice feature to be able to send (and receive) multiple
consecutive requests (/ answers) via the same connection. If that is the
case, it'd be useful to know how to recognize the end of a transmission.

Regards,
-octo

P. S.: Kudos to Luke for his patch, I've applied it to the bugfix
       branches of the source repository.
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
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