Hi,
(First - is this the right list to discuss using TileMill? I can
only find the MapBox support form, or gis.stackexchange.)
I'm having some problems with TileMill rendering very slowly.
Sometimes it seizes up altogether, until I restart it or reboot the
server. This seems to happen particularly when I frequently interrupt
rendering by saving the stylesheet again.
My setup is a 2-core, 8Gb Ubuntu VM running on an OpenStack cluster.
PostGIS (with Melbourne city data from bbbike.org), nginx for auth,
and one shapefile. Pretty vanilla.
I have a few questions about how to improve speed in TileMill/Mapnik:
1) In general, what kinds of rendering rules are slow? Does the way
you specify a rule affect the speed? (eg, is [zoom>13] { #ways[...] }
slower/faster than #ways[...][zoom>13] ?)
2) How does caching take place? It seems to me that when saving a
stylesheet with changes, there's a long delay before anything renders,
then subsequent small changes aren't too slow. So some layers are
computed once then reused?
3) Are there any easy tips for tuning the database?
4) Or tuning TileMill/Mapnik?
5) Watching 'top' during a render, it doesn't look like much memory is
being used. Is there a way to trade memory for speed?
6) Does setting a layer invisible definitely prevent it being
computed? Sometimes I think I'm going mad...
7) Lastly,will adding cores lead to a proportional increase in speed?
Thanks very much in advance,
Steve
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