[Cartoweb-users] CartoWeb caching and map generation

[Sylvain Pasche]

Hello,

What happens actually is the following:

1 Client makes request
2 Server sees it needs to cache request
3 Mapserver is called to generate the map
4 The map is put in the cache.

There is a small window during which a request may be put twice in the
cache: with client A and B:

A 1 make request
A 2 Server sees it needs to cache request
B 1 Client makes request
B 2 Server sees it needs to cache request
A 3 Mapserver is called to generate the map
B 3 Mapserver is called to generate the map

A 4 The map is put in the cache.
B 4 The map is put in the cache.

This is not a problem, because the cache writing operation is atomic.
However, the enhancement would be to block client B which A is caching
the result, so that it can reply with a cached result instead of
computing it again.

I have opened bug 1318 about it:
http://bugzilla.maptools.org/show_bug.cgi?id=1318

Regards,
Sylvain

Le mercredi 01 mars 2006 à 17:49 +0100, Emmanuel Belo a écrit :
> Hello,
> 
> after cleaning the cache, cartoweb generates the new images on request.
> 
> What happens if 10 users ask for the same map during the generation of 
> the first map? Are their request delayed or will 10 processes in 
> parallel be initiated?
> 
> Best regards,
> 
> Emmanuel BELO
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