[Tilecache] Missing Tiles

[Terry Austin]

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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