[Maps-l] Concerning cassini.toolserver.org

[Kai Krueger]

On 04/15/2010 02:38 PM, River Tarnell wrote:
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> Ævar Arnfjörð Bjarmason:
>> Those servers need a lot of love. People other than me have been doing
>> some work on it recently.
>
> I've been distracted by other things the last couple of weeks, but I
> plan to do some working on getting renderd running properly next week.
> We may need some additional programming to make it feasible to run it
> with a lot of styles (e.g. loading styles on demand instead of at
> startup).

It appears as if renderd/Mapnik uses up about 5 - 6 Mb of Ram per 
instance. Part of the problem may be that renderd uses a new instance 
per style per rendering thread. So if you have 250 styles and 8 
rendering threads you end up needing about 250*8*5.5Mb ~ 11 Gb of Ram, 
which sounds  roughly like the numbers given for cassini.

If Mapniks Map Object could be reused for all of the rendering threads, 
that would reduce memory by a factor of 8. It would still be a lot, but 
at least get back into the feasible range. But someone more familiar 
with Mapniks internals would have to comment on that.

Otherwise implementing a load on demand with a time based expiry for map 
styles might not be a bad idea, given that most of the 250 odd styles 
will likely very seldom be used and sounds like it wouldn't be too hard 
to implement.

Kai

>
> 	- river.
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