Centos – How to permanently set ulimit -n 8192 in Centos 7

Under Leopard the initial process is launchd. The default ulimits of each process are inherited from launchd. For reference the default (compiled in) limits are

$ sudo launchctl limit
    cpu         unlimited      unlimited      
    filesize    unlimited      unlimited      
    data        6291456        unlimited      
    stack       8388608        67104768       
    core        0              unlimited      
    rss         unlimited      unlimited      
    memlock     unlimited      unlimited      
    maxproc     266            532            
    maxfiles    256            unlimited

To change any of these limits, add a line (you may need to create the file first) to /etc/launchd.conf, the arguments are the same as passed to the launchctl command. For example

echo "limit maxfiles 1024 unlimited" | sudo tee -a /etc/launchd.conf

However launchd has already started your login shell, so the simplest way to make these changes take effect is to restart our machine. (Use >> to append to /etc/launchd.conf.)

These limits came from a time where multiple "normal" users (not apps) would share the server, and we needed ways to protect them from using too many resources.

They are very low for high performance servers and we generally set them to a very high number. (24k or so) If you need higher numbers, you also need to change the sysctl file-max option (generally limited to 40k on ubuntu and 70k on rhel) .

Setting ulimit:

# ulimit -n 99999

Sysctl max files:

#sysctl -w fs.file-max=100000

Also, and very important, you may need to check if your application has a memory/file descriptor leak. Use lsof to see all it has open to see if they are valid or not. Don't try to change your system to work around applications bugs.