[SAC] projectsVM: rsync reniced to 10

[Tim Schaub]

Hi Martin,

On Sat, May 26, 2012 at 2:21 AM, Martin Spott <Martin.Spott at mgras.net> wrote:
> Hi Tim,
>
> On Thu, May 24, 2012 at 06:09:57PM -0600, Tim Schaub wrote:
>
>> I've removed three uses of rsync in the script that updates the hosted
>> OpenLayers sites.  I'm hoping this will alleviate future problems.  I
>> see someone has added "nice" to our cron job.
>>
>>     # m h  dom mon dow   command
>>     33 * * * *  nice -n 18
>> /osgeo/openlayers/repos/openlayers/tools/update_dev_dir.sh
>
> ....  and set it to an hourly schedule instead of running the "rsync"
> job every minute.
> As far as I can tell, the issue we faced was triggered by "rsync" jobs
> accumulting, because every individual of them didn't finish within one
> minute.  Maybe the remote end was almost unavailable or at least very
> slow.  Thus, with every new "rsync" every minute, the remote end was
> responding even slower than before, leading to a pile of pending
> "rsync" jobs with no chance to recover.
>
> I'd say it's ok to run a "touch ${HOME}/.crond-running" every minute,
> but running an "rsync" job which highly depends on network latency as
> well as on the availability and performance of the remote end is rude -

Don't think we can roll back to see what the frequency of the cron job
really was before, but my recollection was that the job was running
every 15 minutes.  At least this is how things were 6 months ago or
so.  Can't say when this might have changed.

In addition, the rsync should only be happening when there are changes
[1].  So, less than once every fifteen minutes in general.  And the
rsync is between local directories - so I'm not sure "highly depends
on network latency" is appropriate here.  Though maybe you're
referring to the `git ls-remote ...`.

Again, I appreciate the feedback.  Please know that in setting it up,
I didn't think that synchronizing local directories less than every
fifteen minutes would be considered rude.  It sounds like one way or
another, it ended up behaving differently than it was intended.

Thanks again for any suggestions on making additional changes to the
scripts that maintain the OpenLayers website.

Tim

[1] https://github.com/openlayers/openlayers/blob/master/tools/update_dev_dir.sh#L5-9


> especially in a case when the maintainer of the respective job doesn't
> monitor the primary communication channel for the ressources he's
> using.
>
> >From my perspective I'd recommend to leave things in the current state
> and to check early for upcoming trouble.
>
> Cheers,
>        Martin.
> --
>  Unix _IS_ user friendly - it's just selective about who its friends are !
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-- 
Tim Schaub
OpenGeo http://opengeo.org/
Expert service straight from the developers.