#adduser www first http://gadelkareem.com/2012/02/26/adding-new-users-and-admins-to-linux-server/
ulimit -n unlimited - www
#check default number of concurrently open file descriptors 
cat /proc/sys/fs/file-max
#set the number to high value depending on server config
echo '1773914' > /proc/sys/fs/file-max
echo 'fs.file-max=1773914' >> /etc/sysctl.conf
/sbin/sysctl -w fs.file-max=1773914

vi /etc/security/limits.conf
#add
@www           -    nofile          1000000
@www           -    nproc          unlimited
@www           -    memlock          unlimited
@www           -    locks          unlimited
@www           -    core          unlimited
 
@mysql           -    nofile          1000000
@mysql           -    nproc          unlimited
@mysql           -    memlock          unlimited
@mysql           -    locks          unlimited
@mysql           -    core          unlimited

/etc/init.d/network restart