What are zombie processes and why are they bad?

Zombie processes are processes in the operating system that have finished execution but have not yet been completely removed from the process table because their parent process did not invoke the wait() system call to obtain the termination status.

Why is this bad:

• Zombies occupy entries in the process table, which is limited in size. If there are many such processes, it can lead to resource exhaustion and the inability to create new processes.
• They do not consume CPU or memory but clutter system data and complicate monitoring.