[MapProxy] FYI: Possible root cause of 'sqlite3.OperationalError: database is locked'

[Oliver Tonnhofer]

Hi,

a few users reported 'sqlite3.OperationalError: database is locked’ during seeding or moderate load when using SQLite or MBTiles backends. I could never reproduce and debug this on my systems, but I think that I found the root cause. 

On some systems SQLite is not compiled with USLEEP support. Without USLEEP, SQLite will sleep a whole second every time another thread/process is reading or writing to the same SQLite database. 

Here is a detailed description of the issue: http://beets.radbox.org/blog/sqlite-nightmare.html

You should try to upgrade your system or the SQLite version used by Python if you see these lock errors.


Regards,
Oliver

-- 
Oliver Tonnhofer  | Omniscale GmbH & Co KG  | http://omniscale.com
OpenStreetMap WMS and tile services         | http://maps.omniscale.com