What is a zombie process? What is the OOM Killer?

Zombie process — a process in the operating system that has finished execution, but its entry in the process table has not yet been removed because the parent process has not called wait() to obtain its exit status. Zombie processes do not use CPU or memory but occupy a slot in the process table, which can lead to resource exhaustion.

OOM Killer (Out-Of-Memory Killer) — a mechanism in the Linux kernel that activates when there is a shortage of RAM. When the system runs out of memory, the OOM Killer selects and terminates one or more processes to free up memory and maintain system stability. The process selection is based on various criteria such as memory consumption, process priority, and runtime.