Hello!
On Tue, May 04, 2010 at 12:10:26PM -0400, Barry Jaspan wrote:
> Maxim,
>
> Thank you for your reply.
>
> On Mon, May 3, 2010 at 7:58 PM, Maxim Dounin <mdounin@mdounin.ru> wrote:
> > You had at least 7 connections (*1, *2, *4, *6, *8, *9, *10)
> > during the test. First 3 were passed through, others were
> > rejected. ... Most likely you configured nginx to proxy to itself and this
> > causes extra connections.
>
> I understand how making nginx proxy to itself would cause extra
> connections and how those might make all of the initial connections
> fail. If the limit is 3, I open 3, then each of those 3 attempt to
> proxy to nginx again, nginx will return 503 to the proxy request which
> will then be returned to the original requests.
>
> However, I do not see how that is happening in my case.
Sure, but 1) you haven't provided any evidence it doesn't happen
with 3 requests and 2) even assumming it doesn't happen - nobody
says loop is unconditional.
> I have reduced
> my configuration file to a minimum. Here it is:
>
> ---- snip snip ----
> user nginx;
> worker_processes 10;
> error_log /var/log/nginx/error.log debug;
> pid /var/run/nginx.pid;
> events {
> worker_connections 2048;
> }
> http {
> proxy_set_header Host $host;
> limit_zone max_conn $host 10m;
> limit_conn max_conn 3;
> server {
> listen 80;
> server_name _;
> location / {
> proxy_pass http://10.252.86.98;
> }
> }
> }
> ---- snip snip ----
>
> Does this config file make nginx proxy to itself? I do not see how.
The question is: what handles connections on 10.252.86.98:80 and
how it handles them? In most simple case it's the same nginx, and
loop is clear enough.
[...]
> Any thoughts?
Your logs clearly show there are more requests than you expect
from ab. And your config doesn't make proxy loop impossible.
You may either remove "proxy_set_header Host $host" to make sure
Host header in original request will differ from one in proxied,
or add something like
proxy_set_header X-Loop-Test washere;
to make sure requests will be at least distingushable in debug
log.
Maxim Dounin
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