TCP Socket TIME_WAIT problem

Fri Jun 22 09:51:46 UTC 2012

Hi folks,
I'm deeply testing NGINX to understand boundaries and limits because I'd
like to create a webservice for an high performance application in our
LAN. I'm currently running NGINX 1.2.1 on Linux and I'm just serving a
static webpage ("<html><body>Hello World</body></html>") to see
performances. This website is accessed on localhost from a dummy bash
script:
#!/bin/bash
for i in {0..50000}; do
    echo $i
    wget http://127.0.0.1/test.html  -q -O - >> /dev/null
done

In other terminals I'm monitoring sockets and their status ( netstat -an
|grep WAIT|wc -l )
When I run the bash script I can see no troubles until I reach 28233
TIME_WAIT connections, then it freezes for a while until some TIME_WAIT
connections are closed. Performances are ok until I reach this limit,
then everything is frozen for a while until TCP time_wait connections
are disposed
After few researches with google I've found these info:
http://developerweb.net/viewtopic.php?id=2941
http://developerweb.net/viewtopic.php?id=2982

I'm running tests on a pretty fast machine: Intel core i7 with 8Gb RAM
and a Gentoo Linux OS with kernel 3.12, is there a way to get a rid of
this limit ? I'll post here my nginx.conf but please let me know if you
need more info or config files

user nginx nginx;
worker_processes 1;
error_log /var/log/nginx/error_log info;
events {
	worker_connections 1024;
	use epoll;
}
http {
	include /etc/nginx/mime.types;
	default_type application/octet-stream;
	log_format main
		'$remote_addr - $remote_user [$time_local] '
		'"$request" $status $bytes_sent '
		'"$http_referer" "$http_user_agent" '
		'"$gzip_ratio"';
	client_header_timeout 10m;
	client_body_timeout 10m;
	send_timeout 10m;
	connection_pool_size 256;
	client_header_buffer_size 1k;
	large_client_header_buffers 4 2k;
	request_pool_size 4k;
	gzip on;
	gzip_min_length 1100;
	gzip_buffers 4 8k;
	gzip_types text/plain;
	output_buffers 1 32k;
	postpone_output 1460;
	sendfile on;
	tcp_nopush on;
	tcp_nodelay on;
	keepalive_timeout 75 20;
	ignore_invalid_headers on;
	index index.php index.html;
	server {
		listen 127.0.0.1;
		server_name localhost;
		root /var/www/localhost/htdocs;
                location ~ .*.php$ {
                    include /etc/nginx/fastcgi.conf;
                    fastcgi_pass  127.0.0.1:1234;
                    fastcgi_index index.php;
                }
	}
}

Thanks in advance for your reply
Ben

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,227804,227804#msg-227804