Re: [Maposmatic-dev] daily update stats

[Thomas Petazzoni]

Le Wed, 6 Jan 2010 18:20:05 +0100,
Jeroen van Rijn <address@hidden> a écrit :

> Question: Is there a comparison between the time it takes to run
> osm2pgsql with and without jobs being rendered at the same time?

We haven't done measurements of this.

> Likewise, how long does a job take when run at the same time as the
> update process, and how long does it take without?

See results at http://news.maposmatic.org/?p=58

> If it takes for example only half the time when the update is run when
> there's no rendering activity, it may make sense to schedule the job
> to be run from midnight until how-ever-long-it-takes, and to suspend
> the rendering queue until it's completed. As long as it's stated
> outright that jobs will only be processed during the hours of ... and
> ... (and saying this is because the map is kept up to date in the
> downtime), I can see people accepting this.

The daily update already starts "late" in the evening, for European
people (22:42 PM Paris time). It's true that we could suspend the
rendering while the daily update is in progress. But this would
basically mean that people leaving in the US would probably have to
wait the next day to get the result of their rendering.

I definitely think that the huge peak of rendering requests we've been
having the last couple of days will calm down, and that we will get
back to a more normal situation by next week.

> Alternatively it may be interesting to investigate if the daily update
> can be split into parts, to be run at times of lower load; if the
> entire update hasn't finished by some deadline, *then* suspend the
> rendering queue and run the rest of the update.

This is also interesting. But at least for the moment, our
understanding of osm2pgsql is too limited to implement such a thing.
Any osm2pgsql expert in the room ? If so, we may have a lot of
questions :-)

Regards,

Thomas
-- 
Thomas Petazzoni                         http://thomas.enix.org
Promouvoir et défendre le Logiciel Libre http://www.april.org
Logiciels Libres à Toulouse              http://www.toulibre.org

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