[Tilesathome] Duplicates?

[Florian Lohoff]

On Wed, Sep 03, 2008 at 11:51:33PM +0100, Ed Loach wrote:
> All the tiles I've rendered recently have been recently rendered by someone else based on a request at exactly the same time, about 10 or 11 hours ago. Surely this is unnecessary repetition, until a new request is received.
> 
> e.g.
> http://tah.openstreetmap.org/Browse/details/tile/12/1559/2298/
> Schoos and I both rendered based on seemingly the same request (2 hrs 10)
> 
> http://tah.openstreetmap.org/Browse/details/tile/12/1557/2283/
> SabineSW and me (11hrs 32)
> 
> I've just started
> http://tah.openstreetmap.org/Browse/details/tile/12/2125/1385/
> that bigbro has already finished (request 11hrs 34 ago)
> 
> Is it just me? Or is this to do with the lock changes not quite working perfectly?

It a known bug in the server code having a small race condition -
Clients asking for a tile at more or less the same time might get the
same tile handed.

Spaetz tried to fix it (which is non trivial as it needs transactions on
the db) and failed because the database deadlocked.

He'll retry when there is time ... Better to render a tile twice than
noone rendering a tile.

Flo
-- 
Florian Lohoff                  flo at rfc822.org             +49-171-2280134
	Those who would give up a little freedom to get a little 
          security shall soon have neither - Benjamin Franklin
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