If the memory runs out the kernel just use an agent which will try to free some memory by killing those processes which are both old and fat (i.e. use a lot of memory for too long). Every process comes with a score which is constantly updated by the kernel. You can view the score by lurking in /proc/$PID/oom_score.

This article briefly describes how you can find out which process has the biggest change to being killed in a “out of memory” event and how to protect those which are required (e.g. ssh daemon for a remote machine) .

When the OOM killer is called, the process which will most likely be the first victim, is the one with the top score. Here is a little bash script that will show you the running processes sorted by score in ascending order: