Talk me through the upstream process

[Alan Williamson]

So far I am loving nginx; its doing what lighhtpd was doing but no where 
near consuming the CPU.  Result.

I would like to understand how it manages the pool of backend machines. 
  Say for example I have:

upstream backends {
  server 10.0.0.150:80 weight=2;
  server 10.0.0.153:80;
  server 10.0.0.154:80;
}

Now, assume one of them goes off line, the others one will pick up the 
load, but when will nginx decide to put it back into the pool of 
available workers?   Does every new connection coming in, trigger an 
attempt to the offline servers?

Maybe there is some docs i am missing that explains this already, but 
any pointers would be appreciated.

a

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Alan Williamson
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