Weird timeouts, not sure if I've set the right threshholds

[Igor Sysoev]

On Wed, Apr 30, 2008 at 09:37:09PM -0700, mike wrote:

> It is proxying (basically just load balancing) to 3 upstream nginx
> webservers which do FastCGI/PHP/normal static files.
> 
> I get a lot of "upstream timed out" errors and I can't determine why
> exactly. Perhaps my buffers are too high, too low, timeouts are too
> high, too low? I bumped up the timeouts on my proxy machine higher
> than I normally would set so it wouldn't timeout as often but it still
> does. All the machines are quad-core xeons with 4GB RAM, SATA2 disks,
> dedicated to web/fastcgi/php, all connected via a private gigabit
> VLAN... the files are hosted on NFS, but I'm not seeing any errors
> related to that in logs either..

The timeout errors have a "while ..." string that describes conditions,
when the error has happened.

> nginx PROXY:
> 
> user www-data www-data;
> worker_processes 4;
> worker_cpu_affinity 0001 0010 0100 1000;
> working_directory /var/run;
> error_log /var/log/nginx/error.log error;
> pid /var/run/nginx.pid;
> 
> events {
>     worker_connections  1024;
> }
> 
> http {
>     upstream webservers {
>         server web01:80;
>         server web02:80;
>         server web03:80;
>     }
>     include /etc/nginx/mime.types;
>     default_type application/octet-stream;
>     sendfile on;
>     tcp_nopush on;
>     tcp_nodelay on;
>     client_max_body_size 100m;
>     client_header_buffer_size 8k;
>     large_client_header_buffers 12 6k;
>     keepalive_timeout 5;
>     gzip on;
>     gzip_static on;
>     gzip_proxied any;
>     gzip_min_length 1100;
>     #gzip_http_version 1.0;
>     gzip_comp_level 2;
>     gzip_types text/plain text/html text/css application/x-javascript
> text/xml application/xml application/xml+rss
>     gzip_disable "MSIE [1-6]\.";
>     gzip_vary on;
>     server_names_hash_max_size 4096;
>     server_names_hash_bucket_size 128;
>     server {
>         listen 80;
>         access_log off;
>         location / {
>             proxy_pass http://mikehost;
>             proxy_next_upstream error timeout http_500 http_503 invalid_header;
>             proxy_max_temp_file_size 0;
>             proxy_read_timeout 50;
>             proxy_connect_timeout 30;
>             proxy_set_header Host $host;
>             proxy_set_header X-Real-IP $remote_addr;
>             proxy_ignore_client_abort on;
>         }
>     }
> }
> 
> 
> nginx WEBSERVERS:
> 
> user www-data www-data;
> worker_processes 4;
> worker_cpu_affinity 0001 0010 0100 1000;
> working_directory /var/run;
> error_log  /var/log/nginx/error.log debug;
> pid /var/run/nginx.pid;
> 
> 
> 
> events {
>     worker_connections  1024;
> }
> 
> http {
>     include       /etc/nginx/mime.types;
>     default_type  application/octet-stream;
> 
>     set_real_ip_from 10.13.5.16;
>     access_log off;
>     sendfile on;
>     tcp_nopush on;
>     tcp_nodelay on;
>     client_max_body_size 100m;
>     client_header_buffer_size 8k;
>     large_client_header_buffers 12 6k;
>     keepalive_timeout  5;
>     server_tokens off;
>     gzip off;
>     gzip_static off;
>     server_names_hash_max_size 4096;
>     server_names_hash_bucket_size 128;
> 
> # then an example vhost block
>  server {
>     listen 80;
>     server_name michaelshadle.com www.michaelshadle.com;
>     index index.php;
>     root /home/mike/web/michaelshadle.com/;
>     location ~ .php {
>         include /etc/nginx/fastcgi.conf;
>         fastcgi_pass 127.0.0.1:11000;
>         fastcgi_index index.php;
>     }
>     if (!-e $request_filename) {
>         rewrite ^(.+)$ /wordpress/index.php?q=$1 last;
>     }

Instead of this "if" it's better to use:

      location / {
          error_page  404  = //wordpress/index.php?q=$uri;
      }

> }
> 
> 
> Any thoughts? Would turning off some buffers on the proxy make it
> better, or would turning off buffering on the webservers make it
> better? Not quite sure here where the best place would be to change
> (if anywhere...)

The timeout errors has no relation to buffers. These errors usually
means that backends are too slow.


-- 
Igor Sysoev
http://sysoev.ru/en/