[OSM-talk] [OSM-dev] Software development - most pressing issues

[Tom Hughes]

On Nov 29, 2007 6:14 PM, Robert (Jamie) Munro <rjmunro at arjam.net> wrote:

> Tom Hughes wrote:
>
> > I think live rendering is pretty much permanently off now because the
> > queue is so long it wouldn't kick in anyway - it was only ever used
> > when the queue was short.
>
> That seems backwards to me. The queue should only be processed when live
> rendering isn't going on. Things should only be added to the queue when
> the live rendering service is too busy, or if they are too low a zoom to
> practically render live.

That's more or less what happens with mod_tile - if apache thinks a
tile is stale it asks renderd to render it. In renderd there are two
queues - a live queue and the main dirty queue - if the live queue is
short then the tile is added to that and renderd waits for it to
complete before replying to apache. Otherwise it is added to the main
queue and apache is told to go ahead and serve the old versions.

The render threads then pull tiles from the live queue, or if that is
empty the main queue, and renders them.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/