[Tilecache] Problem moving tilecache from Ubuntu 12.04 to 14.04

[Stephen Woodbridge]

After two days of trying to fix this problem and not making any headway, 
I gave up and converted the project over to mapcache which was pretty 
easy and straight forward. The whole conversion took about 1 hr to 
create the mapcache.xml file equivalent to the tilecache.cfg and to edit 
the html to point to mapcache and enable it in apache. This used the 
existing cache so I didn't need to repopulate it.

-Steve

On 7/7/2015 3:21 PM, Stephen Woodbridge wrote:
> Hi All,
>
> I'm having a problem upgrading a system with tilecache installed on it.
> After two days and no headway, I probably am missing some basic or I've
> hit a real problem.
>
> The Problem:
>
> On the 14.04 server:
>
> http://74.208.113.181/tilecache-2.01/tilecache.py?LAYERS=bathy_contours&FORMAT=image%2Fpng&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A4326&BBOX=-73.4,29.6,-71.8,31.2&WIDTH=256&HEIGHT=256
>
>
> Errors out with:
> An error occurred: Current x value -73.400000 is too far from tile
> corner x -75.000000
>
> but with the same url on the 12.04 server I get an image:
>
> http://74.208.78.238/tilecache-2.01/tilecache.py?LAYERS=bathy_contours&FORMAT=image%2Fpng&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A4326&BBOX=-73.4,29.6,-71.8,31.2&WIDTH=256&HEIGHT=256
>
>
> some tiles are returned correctly and some are not. Here is one that works:
>
> http://74.208.113.181/tilecache-2.01/tilecache.py?LAYERS=bathy_model&FORMAT=image%2Fpng&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A4326&BBOX=-76.6,36,-75,37.6&WIDTH=256&HEIGHT=256
>
>
> http://74.208.78.238/tilecache-2.01/tilecache.py?LAYERS=bathy_model&FORMAT=image%2Fpng&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A4326&BBOX=-76.6,36,-75,37.6&WIDTH=256&HEIGHT=256
>
>
> Situation:
>
> Ubuntu 12.04 LTS server running:
> tilecache/precise uptodate 2.11-2
> apache2/precise-security 2.2.22-1ubuntu1.8
> python/precise-updates uptodate 2.7.3-0ubuntu2.2
>
> and in the apache sites-enabled:
>          Alias /tilecache-2.01 /var/lib/python-support/python2.7/
>          <Directory /var/lib/python-support/python2.7/>
>                  SetHandler python-program
>                  PythonHandler TileCache.Service
>                  PythonOption TileCacheConfig /etc/tilecache.cfg
>          </Directory>
>
>
> I setup a new server and rsync the tilecache, the /etc/tilecache.cfg and
> set it up using:
> tilecache:all/trusty 2.11-2 uptodate
> apache2:amd64/trusty-security 2.4.7-1ubuntu4.4 uptodate
> python:amd64/trusty 2.7.5-5ubuntu3 uptodate
> python2.7:amd64/trusty-security 2.7.6-8ubuntu0.2 uptodate
> python3:amd64/trusty 3.4.0-0ubuntu2 uptodate
> python3.4:amd64/trusty-security 3.4.0-2ubuntu1.1 uptodate
>
> # python --version
> Python 2.7.6
>
> and in the apache sites-enabled:
>          Alias /tilecache-2.01 /var/lib/python-support/python2.7/
>          <Directory /var/lib/python-support/python2.7/>
>                  #SetHandler python-program
>                  AddHandler python-program .py
>                  PythonHandler TileCache.Service
>                  PythonOption TileCacheConfig /etc/tilecache.cfg
>                  Require all granted
>          </Directory>
>
> The cache should be fully populated so there should be not need to hit
> mapserver but I occasionally get mapserver processes running at 100% for
> long periods of time, probably because the cache thinks it needs to
> generate a metatile. I probably will need to check mapfiles because the
> old server is running MapServer version 6.2.1 and the new server is on
> MapServer version 6.4.1
>
> Problem Analysis:
>
> This is probably faulty or incomplete as it has not lead me to a solution.
>
> 1. tilecache is configured and running
> 2. different versions of apache 2.2 vs 2.4
>     - had to make changes in handler above
>     - are there other changes like environment variables or initialization
> 3. system has both python 2.7 and 3.0 installed is something strange
> happening because of this?
> 4. are the differences in mod_python between the two systems that might
> cause this?
> 5. there appears to be a pattern to what tiles are ok or broken but its
> not clear what it means. Maybe some kind of rounding issue?
> 6. I diff'd the files in /var/lib/python-support/python2.7/ tree and
> they are all the same except a few of the pyc files. I recompiled them
> on the new system just be be sure with python -m py_compile
> /path/to/file.py but that did not change anything.
>
> I looked at the Layer.py code and it is failing in getCell() at:
>
>          if exact:
>              if (abs(minx - tilex)  / res > 1):
>                  raise TileCacheException("Current x value %f is too far
> from tile corner x %f" % (minx, tilex))
>
> because abs(minx - tilex) / res = 256 which seems curious as this is the
> size of a tile. So I'm thinking that this code might be behaving badly:
>
>      def getResolution (self, (minx, miny, maxx, maxy)):
>          """
>          >>> l = Layer("name")
>          >>> l.getResolution((-180,-90,0,90))
>          0.703125
>          """
>          return max( float(maxx - minx) / self.size[0],
>                      float(maxy - miny) / self.size[1] )
>
> I'm getting res=0.00625 for the broken request.
>
> So the bottom line, I'm totally lost in this issue and probably looking
> in all the wrong places.
>
> -Steve
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