[SSSD] [PATCH] Set c-ares to retry nameservers

Stephen Gallagher sgallagh at redhat.com
Thu May 12 15:49:54 UTC 2011


On Thu, 2011-05-12 at 17:48 +0200, Jakub Hrozek wrote:
> On 05/12/2011 02:23 PM, Stephen Gallagher wrote:
> > On Thu, 2011-05-12 at 13:07 +0200, Jakub Hrozek wrote:
> >> https://fedorahosted.org/sssd/ticket/867
> >>
> >> channel->tries is only used when a query fails. We were forcibly setting
> >> it to 0, which meant we never retried another server.
> > 
> > From the c-ares manual:
> > 
> > ARES_OPT_TRIES int tries;
> > The number of tries the resolver will try contacting each name server
> > before giving up. The default is four tries. 
> > 
> > 
> > We originally set it to zero because the above entry used to read "the
> > number of retries", not tries.So zero retries was supposed to mean one
> > try per server.
> > 
> > Can you verify in the c-ares code that this isn't a behavior that
> > CHANGED between versions (and thus we might need to detect the version
> > in use and handle it?)
> > 
> 
> The code in question in c-ares is called only when a search fails and
> reads (simplified):
> 
> -------
> while (++try < (nservers * tries)) {
>   /* Get next server */
>   /* Send the query again */
> }
> 
> /* Mark query as failed */
> -------
> 
> Since we had tries=0, we skipped the failover part and immediately
> marked the query as failed.
> 
> The code is the same in c-ares 1.6 (RHEL5) and 1.7 (RHEL6 and supported
> Fedora versions).


With this in mind, Ack.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part
URL: <https://lists.fedorahosted.org/pipermail/sssd-devel/attachments/20110512/c094e5ff/attachment.sig>


More information about the sssd-devel mailing list