A zombie process is a process in an operating system whose execution is completed, but the process still has an entry in the system process table despite it no longer being active in any way. This is usually caused by the parent process failing to properly clean up the processes it has spawned when they have finished their work. While a zombie process does not use any system resources, it will not die until its parent process dies or it is terminated manually.
Zombie processes have no output and they cannot be interacted with in any way. They can be identified by their ‘defunct’ or ‘zombie’ status.
If a zombie process is left unattended for too long it can cause system resource problems as the process table becomes cluttered with inoperable tasks. To avoid the accumulation of zombie processes, proper clean up of child processes by their parent processes is essential. This is usually done by using the wait() system call, which waits for the child processes to terminate before continuing with the parent process.
As zombie processes are an issue often caused by improper programming, modern programming language libraries often come with methods that simplify the task of executing and cleaning up child processes.
In some cases, it may be necessary to manually terminate zombie processes with kill() system calls. Understanding how to identify and address zombie processes is important for system administrators to ensure smooth system operations.
