question about workers and proxying to dead upstream.

[Adrian Bak]

Thanks... That's what I wanted to hear.
Now I go on and try to sell it to the "big man upstairs" :)

best,
Adrian

2009/5/5 Igor Sysoev <is at rambler-co.ru>:
> On Mon, May 04, 2009 at 11:49:45PM +0200, Adrian Bak wrote:
>
>> Hey guys...
>>
>> We have a setup where we serve static files from our nginx servers and
>> if the file doesn?t exist we proxy to a backend server (that generates
>> a static file, and we have another app to delete the static files when
>> they get to old).
>>
>> The config file looks something like this (on my machine i am testing
>> with an apache running on port 8888):
>>
>> worker_processes  1;
>> events {
>>     worker_connections  5; # 5 for testing. would be much higher in production
>> }
>>
>> ...
>>
>> upstream dynamic {
>>         server localhost:8888;
>> }
>>
>> location / {
>>             ssi on;
>>             try_files $uri $uri/index.html @nothere;
>>             break;
>> }
>>
>> location @nothere {
>>             break;
>>
>>             proxy_redirect on;
>>
>>             # setting extra header
>>             proxy_set_header   X-Real-IP        $remote_addr;
>>             proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
>>
>>             # setting timeout values for the proxying
>>             proxy_connect_timeout      90;
>>             proxy_send_timeout         90;
>>             proxy_read_timeout         90;
>>
>>             # setting proxy buffer sizes
>>             proxy_buffer_size          4k;
>>             proxy_buffers              4 32k;
>>             proxy_busy_buffers_size    64k;
>>             proxy_temp_file_write_size 64k;
>>
>>             proxy_pass http://dynamic;
>>     }
>>
>> Anyways my question is: what happens if there are 5 (number of
>> worker_connection*number_worker_processes) connections to a non
>> existing file (it has to proxy) and the backend server times out (i
>> have a sleep in my php for testing purpose)?
>> Can nginx still serve static files (file that exist)?
>> Will it allow 5 connections to the upstream?
>>
>> I can?t find the answer on the wiki anywhere and my own test?s with ab
>> and curl show that it won?t allow for 5 connections to upstream
>> servers if it?s hanging on one of them (it will show a ?The page you
>> are looking for is temporarily unavailable.
>> Please try again later.?) - is this correct?
>
> Yes. Note also, that one connection is required for client side,
> and one connection is required for proxy/fastcgi side. Therefore
> for each proxied request you need 2 connections.
>
>
> --
> Igor Sysoev
> http://sysoev.ru/en/
>
>