[OSM-dev] Multiple instances of Renderd?

Frederik Ramm frederik at remote.org
Wed Mar 30 12:42:07 BST 2011


Hi,

On 03/30/2011 01:21 PM, Jason Lee wrote:
> Regarding multiple instances, I am just thinking in terms of performance
> and stability. If I had 2 instances of renderd and one error's for
> whatever reason, then at least it is not affecting the other service.

Having two renderd processes serving the same maps is asking for trouble 
(depending on how you balance the load, the same tile might end up being 
rendered twice and suchlike).

Having two renderd processes serving different maps should be possible. 
You will have to set up different Apache vhosts, each configuring 
mod_tile to use a different Unix domain socket for talking to renderd, 
and you will have to start multiple instances of renderd, one for each 
socket. If you don't modify the source code, each renderd will use the 
same pidfile which means you will have to use non-standard means to shut 
them down. Also, this method would mean that each renderd has a queue of 
its own which may lead to a less even distribution of performance, and 
issues with queue length and so on if several of your maps are used heavily.

In short, I wouldn't recommend it.

Bye
Frederik




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