[Tilecache] Missing Tiles

[Alexandre Dube]

For the record,

  I also had this kind of error happening using tilecache 2.04 on a 
linux platform with CGI mode and using metaTile=true and didn't find why 
yet.  Like you, I switched to metaTile=false to resolve this. 

http://openlayers.org/pipermail/tilecache/2008-December/001551.html

Alexandre

Terry Austin wrote:
> All,
>
> On a Windows Vista / Apache 2.2 / mod_python / TileCache 2.10 -> 
> MapServer WMS / OpenLayers setup with no pre-seeding, I'm seeing 
> missing tiles on virtually every significant load of tiles in a given 
> view like when changing resolutions or when the view requires loading 
> a lot of tiles because of a pan.  This only occurs when the metaTile 
> option is on.  Turning off metaTiling makes all tiles appear (but has 
> the visual limitations of not using metatiles).  I'm seeing this in my 
> Apache logs with about the same frequency as the missing tiles:
>
> unlock 
> D:\Data\Gis\TN\tilecache\tn\version00001\all\07\000\000\060\000\000\013.png.lck 
> failed: [Error 2] The system cannot find the file specified: 
> 'D:\\Data\\Gis\\TN\\tilecache\\tn\\version00001\\all\\07\\000\\000\\060\\000\\000\\013.png.lck'
>
> Not sure if that has anything to do with it.  Does this seem like a 
> locking issue (only metatiles use locks?), or is it some wacky Vista 
> TCP limitation thing?  I think that the tile is actually generated 
> because reloading the page makes everything appear correctly.  Also, 
> just using the URL of the missing tile in another browser tab works 
> correctly, so I know the tile can be generated.
>
> Not sure if it's related, but when I try to pre-seed it fails with a 
> "Zero length data returned from layer." error pretty early in the 
> process (after generating only a few tiles).
>
> I'm pretty new to both Python and TileCache, so I may be missing 
> something simple.  Any thoughts on this would be appreciated.
>
> Terry Austin
> Progressive Partnering
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-- 
Alexandre Dubé
Mapgears
www.mapgears.com