[SSSD] [PATCH] Exit offline mode only if server is available.

Jakub Hrozek jhrozek at redhat.com
Mon Jul 7 13:01:22 UTC 2014


On Mon, Jul 07, 2014 at 02:11:52PM +0200, Michal Židek wrote:
> On 07/06/2014 06:44 PM, Simo Sorce wrote:
> >On Sun, 2014-07-06 at 12:42 -0400, Simo Sorce wrote:
> >>On Fri, 2014-07-04 at 12:34 +0200, Michal Židek wrote:
> >>>Hi Sumit,
> >>>
> >>>actually your suggestion was one of my first ideas, but
> >>>It looked like strange behaviour to me if the first
> >>>getent (or any request for data not present int the
> >>>cache) after offline_timeout period returned nothing
> >>>even if the server was already available and the second
> >>>(1 or 2 seconds after the first) returned proper data. I
> >>>thought this may be considered a bug for some people (even
> >>>if it is not a major regression :) ). The patch I sent
> >>>was then an improvement over this initial idea (from my POV).
> >>>
> >>>I understand your suggestion and concern, but I would
> >>>prefer to stick with the approach in the patch I sent.
> >>
> >>Can we at least use a backoff scheme where we increase timeout periods
> >>every time we try and find ourselves offline ?
> >>
> >>Try 1 minute, then 2, then 4, then 8, 16, 32, 64, 128 ...
> 
> Good idea, but this might result in SSSD being too long
> offline for no good reason. Would it make sense
> to introduce a new config option for upper bound of
> this delay (like offline_timeout_max)? Without this option
> it would be difficult for me to accept this change. But
> I wonder what the default value should be... maybe 64?

I would actually prefer to have a sane default..one hour with some
randomization to avoid "8AM flood" maybe.

> 
> >
> >It would also probably be a good idea to randomize a little the delay,
> >otherwise we risk thundering herd situations.
> >
> > Simo.
> >
> 
> Should the maximal value of the random offset be configurable?

I would prefer to have neither the random offset nor the maximum cap
configurable, or have a undocumented option unless we know it makes
sense to let the admin configure the option.

I'm afraid we have too many timeout options already and it's difficult
for admins to know them even without adding onother one..

> Or is it not needed (I personally think it is not, but would like
> to hear other opinions as well)? I am also not sure what the
> default value should be (I was thinking 30 seconds).
> 
> Will send new patches soon, thanks for suggestions.
> 
> Michal




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