Centos – How to set ulimits for mongod

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.)

On Solaris you can set this parameter to be a hard or soft limit system-wide OR you can do the same for a specific application so that it has the correct number of open file descriptors in its run-time space.

To make it a system-wide change, edit /etc/system with following entries

# Hard limit on file descriptors for single process
set rlim_fd_max = 4096

# Soft limit on the file descriptors for a single process
set rlim_fd_cur = 1024

NOTE: without setting rlim_fd_max as shown above, the default value for file descriptors or nofiles is half of the rlim_fd_cur value. So, it's best to set them both.

If you are using a Solaris project for an application space like Oracle Database, you can set the max file descriptors in the project by:

projadd -U oracle -K “process.max-file-descriptor=(priv,4096,deny)” user.oracle

Additionally, you can set it using ulimit directly in an application's owner's shell startup file. For example, it is possible to establish max file descriptors by setting ulimit in the .profile of the web server's owner to ulimit -s 32768 and calling that from the startup/shutdown script.

As you can see there are lots of options and ways of doing this.