[Tilecache] Permissions and TileSize

Matthew Rushton mrushton7 at yahoo.com
Fri Dec 26 12:43:44 EST 2008


Thanks Chris here's some more info:

>From my tilecache.cfg:

[basic]
type=MapnikLayer
layers=basic
mapfile=/opt/tile_server/mapnik/osm.xml
size=64,64
tms_type=google
spherical_mercator=true
metaTile=true

a request which I expect to produce the entire world but is part of a 4x4 grid:
myserver.com/tilecache.py/1.0.0/basic/0/0/0.png

Also I am using mod_python so perhaps the performance isn't as a big deal if the xml isn't being read with every request that was a cache miss. My basic concern was how much faster could I make a custom apache module if I were so inclined. Thanks again!
-Matt

--- On Fri, 12/26/08, Christopher Schmidt <crschmidt at metacarta.com> wrote:
From: Christopher Schmidt <crschmidt at metacarta.com>
Subject: Re: [Tilecache] Permissions and TileSize
To: tilecache at openlayers.org
Date: Friday, December 26, 2008, 11:47 AM

On Fri, Dec 26, 2008 at 08:17:22AM -0800, Matthew Rushton wrote:
> I finally figured out the issue, it ended up being a boundary file
> that had the wrong permissions, so all is good and appears to be
> working. One issue that remains is my tile size. I'm using 64x64 and
> this makes zoom level zero not be the entire world. 

This isn't enough information to understand what you're hoping for.
Please share your TileCache config and a tile that you're looking for. 

> The only other issue I was curious about was performance with osm
> data. I'm worried about the xml file being parsed too frequently.
> Does  anyone have experience with this? Is my concern valid?

Since: 
 * Pre-cached tiles never touch the XML file
 * Non-precached tiles will take much longer to render than to use
   a C-based XML parser to read the XML file

My guess is that your concern is a case of premature optimization.

If you are using mod_python, the config file is read once per apache
child startup. If you are using CGI, it is read with every request that
needs to generate tiles.

-- Chris

> -Matt
> 
> --- On Thu, 12/25/08, Matthew Rushton <mrushton7 at yahoo.com> wrote:
> From: Matthew Rushton <mrushton7 at yahoo.com>
> Subject: 
> To: tilecache at openlayers.org
> Date: Thursday, December 25, 2008, 10:09 PM
> 
> I'm trying to set up TileCache and running into a few problems with
likely simple solutions. I'm using Mapnik to render the tiles to a disk
cache. I previously was using another tile server, so I know mapnik is working
great. This is the error I'm getting below. I know it's a problem with
loading the osm.xml file I just don't know why. I've changed
persmissions so it shouldn't be an issue. What sort of problem could this
be? What do people generally keep the permissions of this file and others,
including tiles, at. Thanks in advance.
> -Matt 
> 
> An error occurred
> 
> : failed opening file: Bad file descriptor
>   File "/var/www/tilecache-2.04/TileCache/Service.py", line 224,
in modPythonHandler
>     host )
>   File "/var/www/tilecache-2.04/TileCache/Service.py", line 208,
in dispatchRequest
>     return self.renderTile(tile,
>  params.has_key('FORCE'))
>   File "/var/www/tilecache-2.04/TileCache/Service.py", line 138,
in renderTile
>     data = layer.render(tile)
>   File "/var/www/tilecache-2.04/TileCache/Layer.py", line 437,
in render
>     return self.renderTile(tile)
>   File "/var/www/tilecache-2.04/TileCache/Layers/Mapnik.py",
line 40, in renderTile
>     mapnik.load_map(m,self.mapfile)
> 
> 
> 
>       
> 
> 
>       
> _______________________________________________
> Tilecache mailing list
> Tilecache at openlayers.org
> http://openlayers.org/mailman/listinfo/tilecache


-- 
Christopher Schmidt
MetaCarta
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