Hi,
I have faced a trouble with nginx runs as a http revers proxy server,the worker process sometimes hanging there, cpu usage up to 100%,it's never recovey until i kill the process,below is the detail informations:

system environment:
[root@host-22 ~]# lsb_release -a
LSB Version: :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch
Distributor ID: CentOS
Description: CentOS release 5.5 (Final)
Release: 5.5
Codename: Final
[root@host-22 ~]#
[root@host-22 ~]# uname -a
Linux host-22 2.6.18-194.el5 #1 SMP Fri Apr 2 14:58:14 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux



nginx version:
[root@host-22 ~]# /usr/local/nginx/sbin/nginx -V
nginx: nginx version: nginx/1.0.4
nginx: built by gcc 4.1.2 20080704 (Red Hat 4.1.2-46)
nginx: TLS SNI support disabled
nginx: configure arguments: --user=www --group=www --prefix=/usr/local/nginx --with-http_stub_status_module --with-http_ssl_module --with-openssl-opt=enable-tlsext --with-http_sub_module --with-cc-opt=-O2 --with-cpu-opt=opteron
[root@host-22 ~]#
(also tested under 1.0.6 and 1.0.9,have the same problem)


nginx config( nginx runs as a http revers proxy server):
worker_processes 8;

events {
use epoll;
worker_connections 5120;
}

http {
sendfile on;
keepalive_timeout 15;
...

upstream 2012_servers {
server 10.0.7.5:80 max_fails=2 fail_timeout=30s;
server 10.0.7.6:80 max_fails=2 fail_timeout=30s;
server 10.0.7.7:80 max_fails=2 fail_timeout=30s;
server 10.0.7.8:80 max_fails=2 fail_timeout=30s;
}


server {
listen 80;
server_name test.2012.com ;
...

location / {
include proxy.conf;
proxy_pass http://2012_servers;
}
...

}



trouble:
[root@host-22 ~]# ps aux|grep -e CPU -e nginx
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 936 0.0 0.0 49328 7572 ? Ss Nov11 2:37 nginx: master process /usr/local/nginx/sbin/nginx
www 1130 99.9 0.0 55764 13472 ? R Nov11 2664:28 nginx: worker process
www 1216 99.9 0.0 53668 11092 ? R Nov11 2660:23 nginx: worker process
www 31057 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process
www 31058 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process
www 31059 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process
www 31060 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process
www 31061 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process
www 31062 0.8 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process
www 31063 0.1 0.0 50816 9012 ? S 19:40 0:00 nginx: worker process
www 31064 0.2 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process

two nginx worker processes(pid 1130,1216) are hanging. there is nothing significant message i can found in error.log or strace (-p 1130|1216).

Grateful for any advice.

thanks.