Hello!

On Sun, Sep 20, 2009 at 10:47:21PM -0700, Khalid Shaikh wrote:

> We are using Nginx on this web server. Look at the # of reading & writing
> requests. a curl http://localhost/test.html can take up to 45 seconds.
> Can anyone help?
>
> Using telnet I can see that basically the Nginx server is taking time to get
> to the TCP connection that I initiated.
>
> This happens only during peak times of the web site.

Looks like either nginx has no CPU time due to fastcgi sitting on
the same machine, or nginx workers are blocked on disk. You may find
out actual reason by examining state of nginx worker processes in
top.

If the problem is CPU time you shuld just add some to nginx, e.g.
by using worker_priority directive. Reducing load on fastcgi
(e.g. by using fastcgi_cache) may help too.

If the problem is disk load, you may try the following:

1. Set sendfile_max_chunk to something like 128k or 256k. This
should prevent fast clients from blocking nginx in sendfile() for
too long.

2. Don't use sendfile at all and use small number of big
output_buffers (e.g. output_buffers 1 256k;). This should reduce
number of disk accesses (and seeks) at cost of not using
sendfile() - e.g. some additional CPU usage.

3. If fastcgi returns big responses that are buffered to disk, try
raising fastcgi_buffers and/or setting fastcgi_max_temp_file_size
0;. This should prevent nginx from going to disk at cost of not
releasing fastcgi connection as early as possible. Also you
should consider finding the source of such responses and using
X-Accel-Redirect instead if it's possible.

4. Consider using aio. Though aio on Linux isn't something
generally usable, but it may help anyway. Note that some bugs may
be still here, it's expiremental feature.

Maxim Dounin

>
> Active connections: 8467
> server accepts handled requests
> 380771 380771 835836
> Reading: 75 Writing: 1497 Waiting: 6895
> http://67.159.60.59/status 45.03 seconds
>
> I've attached the nginx.conf
>
> user www-data www-data;
> worker_processes 32;
>
> error_log /var/www/log/nginx_error.log;
> pid /var/run/nginx.pid;
>
> events {
> worker_connections 10024;
> }
>
> http {
> include /etc/nginx/mime.types;
> default_type application/octet-stream;
>
> sendfile on;
> tcp_nopush on;
> tcp_nodelay on;
>
> server {
> listen 80;
> server_name xs.to;
> root /var/www/xs;
> error_page 404 index.php;
> error_page 500 502 503 504 index.php;
> access_log off;
>
> location / {
> root /var/www/xs;
> index index.php default.php;
> rewrite ^/albums/(.*)$ /albums/showalbum.php?$1? last;
> rewrite ^/community/(.*)$ /community.php?$1? last;
> error_page 404 index.php;
> error_page 500 502 503 504 index.php;
> }
>
> location /status {
> stub_status on;
> access_log off;
> }
>
> location ~ .php$ {
> fastcgi_pass 127.0.0.1:8888;
> fastcgi_index index.php;
> fastcgi_intercept_errors on;
> error_page 404 index.php;
> error_page 500 502 503 504 index.php;
> fastcgi_param SCRIPT_FILENAME /var/www/xs/$fastcgi_script_name;
> include /etc/nginx/fastcgi_params;
> }
>
> location ~* ^.+.(jpg|jpeg|gif|tiff|png|bmp|ico|fav|html)$ {
> access_log off;
> expires 30d;
> }
> }