100% CPU / wedge with 9.8.3-P4 & RPZ?

[Phil Mayers]

On 03/16/2013 06:46 PM, Vernon Schryver wrote:
>> From: Phil Mayers <p.mayers at imperial.ac.uk>
>
>> It's unfortunate I wasn't able to obtain one; gdb wasn't installed on
>> the box, and I couldn't get the package installed because DNS was down.
>
> Depending on the flavor of the system and its configuration, adding
> lines to /etc/hosts can be effective for working around local or
> remote DNS problems.

Thanks. I do know what /etc/hosts does!

To be honest, I was focussed on restoring service. Grabbing a quick core 
dump would have been fine. Spending 10 minutes getting packages 
installed was not (To put in a local hosts entry, I would first have had 
to logged into our IPAM system to find the IP address of the webserver 
running our yum repo. Since DNS was out, login was tricky because the 
Kerberos SRV records could not be resolved).

> I use `kill -6` or another fatal signal.
> Some systems disable by default the creation of core files.  This

Having tested after the event, kill -6 doesn't create a core on my 
system for named. Whether that's permissions or what I don't know and do 
not have time to investigate.

> irritating, simplistic misconfiguration (that's only my view) is
> especially common in the Linux world.  See
> https://www.google.com/search?q=create+core+file

Erm... thanks. I think. But I am broadly familar with the concept of 
using a search engine to find out information...

>
> Gdb would have been handy for looking at named without creating a
> core file or disturbing the process by more than what it would see
> as a jump in time.

Or for running "gcore `pgrep named`" which has the advantages of 
sidestepping all the crap about core file output locations, permissions, 
ulimit and so on.