no performance improvement on nginx reverse-proxy

[Igor Sysoev]

On Wed, Oct 13, 2010 at 12:33:17PM +0800, yung wrote:

> Hello,
> 
> This day I did a simpe test with nginx's reverse-proxy.
> The environment is on a vmware virtual host.
> 
> OS: slackware Linux, kernel 2.6.24.5-smp
> CPU: Intel(R) Celeron(R) CPU          723  @ 1.20GHz
> MEM: 350M
> 
> 
> The application environment:
> 
> nginx version: nginx/0.8.52
> apache version: Apache/2.2.15 (Unix)
> mysql version: 5.1.51
> 
> 
> The performance/capability arguments for nginx/apache are:
> 
> [nginx]
> 
> worker_processes  8;
> events {
>     worker_connections  1024;
> }
> 
> [apache]
> 
> <IfModule mpm_prefork_module>
>     StartServers          5
>     MinSpareServers       5
>     MaxSpareServers      10
>     MaxClients          150
>     MaxRequestsPerChild   0
> </IfModule>
> 
> 
> Apache run with two vhosts, one is listening on 8080 port, another is
> listening on 8081 port.
> 
> The vhost config shown as below:
> 
> <VirtualHost *:8080>
>     DocumentRoot "/usr/local/apache2.2/vhost/vh1"
>     ScriptAlias /cgi/ "/usr/local/apache2.2/vhost/vh1/cgi/"
> </VirtualHost>
> 
> <VirtualHost *:8081>
>     DocumentRoot "/usr/local/apache2.2/vhost/vh2"
>     ScriptAlias /cgi/ "/usr/local/apache2.2/vhost/vh2/cgi/"
> </VirtualHost>
> 
> 
> There are two cgi scripts on the cgi dirs above.
> one is /usr/local/apache2.2/vhost/vh1/cgi/test.cgi
> another is /usr/local/apache2.2/vhost/vh2/cgi/test.cgi
> 
> Their content is do the same.
> It's a simple perl script which fetches a record by random from a
> table which has 150,000 records totally.
> [the script content is pasted on the last of this message.]
> 
> 
> Nginx is setup for the reverse-proxy to the two vhosts of apache.
> The config piece shown as:
> 
>     upstream MyTestServ {
>       server 127.0.0.1:8081;
>       server 127.0.0.1:8080;
>     }
> 
>     server {
>         server_name my.test.com;
>         listen 80;
> 
>         location / {
>           proxy_set_header Host  $host;
>           proxy_set_header X-Real-IP $remote_addr;
>           proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
>           proxy_pass http://MyTestServ;
>         }
>     }
> 
> 
> 
> After all  that done, I tested it with http_load (a tool from
> http://www.acme.com/software/http_load/).
> 
> ./http_load -parallel 15 -seconds 30 urls
> 
> This test nginx for rever-proxy, the url is like:
> http://192.168.0.77/cgi/test.cgi
> 
> 
> ./http_load -parallel 15 -seconds 30 urls1
> 
> This test apache directly, the url is like:
> http://192.168.0.77:8080/cgi/test.cgi
> 
> 
> After testing for some times (have been changing the arugments for
> http_load), I found nginx with reverse-proxy is not better than the
> realserver.
> Even the result is worse for accessing nginx than access apache directly.
> 
> 
> The result with nginx reverse-proxy:
> 
> 191 fetches, 15 max parallel, 9782 bytes, in 30 seconds
> 51.2147 mean bytes/connection
> 6.36667 fetches/sec, 326.067 bytes/sec
> msecs/connect: 1.23155 mean, 3.663 max, 0.648 min
> msecs/first-response: 2250.49 mean, 5026.69 max, 576.448 min
> 90 bad byte counts
> HTTP response codes:
>   code 200 -- 191
> 
> 
> The result with NO reverse-proxy:
> 
> 196 fetches, 15 max parallel, 10030 bytes, in 30.0005 seconds
> 51.1735 mean bytes/connection
> 6.53322 fetches/sec, 334.327 bytes/sec
> msecs/connect: 1.35084 mean, 6.877 max, 0.797 min
> msecs/first-response: 2103.1 mean, 4348.94 max, 535.809 min
> 84 bad byte counts
> HTTP response codes:
>   code 200 -- 196
> 
> 
> So how do you think about it?
> Suggestions are welcome. Thanks.

nginx is not a magic wand, it's just a reverse proxy.
It can help if a bottleneck is a slow client.
In your case bottlenecks are CGI script launches and database queries,
so nginx adds only an overhead as you have seen: 6.5 req/s vs 6.3 req/s.

> __END__
> 
> This is the CGI script for testing:
> 
> #!/usr/bin/perl
> use strict;
> use CGI;
> use DBI;
> 
> my $q=CGI->new;
> print $q->header("text/plain");
> 
> my $dsn = "DBI:mysql:database=pyh;host=127.0.0.1;port=3306";
> my $dbh = DBI->connect($dsn, 'root', '');
> 
> my $id = 10026 + int(rand(150000));
> 
> my $str = "select * from myt2 where id = $id";
> my $sth = $dbh->prepare($str);
> $sth->execute;
> 
> my @array = $sth->fetchrow_array;
> $sth->finish;
> $dbh->disconnect;
> 
> print "@array\n";


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