Out of memory

Check logs like this: cat /var/log/messages | grep memory

Kill process score 10 or sacrifice child

Linux is built with a bunch of ‘daemons’. Those daemons are shepherded by several kernel jobs. Apparently all modern Linux kernels have a built-in mechanism called “Out Of Memory killer” which can annihilate your processes under extremely low memory conditions. When such a condition is detected, the killer is activated and picks a process to kill. The target is picked using a set of heuristics scoring all processes and selecting the one with the worst score to kill.

Source: https://plumbr.eu/blog/memory-leaks/out-of-memory-kill-process-or-sacrifice-child More Info: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-captun.html

Solution: find a process which depletes your RAM and fixed it. Or add more RAM.