Why does the need of process synchronization ?

Question

In the ps results few of the processes are having process state as "D" . What does it mean ? Briefly explain different process states ?

Answer 1

When two or more processes try to access one shared resource, process synchronization is required. The piece of code that access shared resource is known as critical section. Only one process can enter into its critical section. A critical section has enter section and may have exit section.