What is critical section problem?

A race condition at data item occurs when many processes simultaneously update its value data consistency, needs that only one process should update the value of a data item at any time. It ensured by the notion of a critical section.

A critical section for a dataitem d is a section of code, that can't be executed simultaneously with itself or along with other critical section(s) for d.

Notice a system of n processes (P0, P, .Pn-1).

All processes have a segment of code called a critical section, in that the process may be changing common variables, waiting a file and updating a table and so on. Significant feature of the system is, while one process is executing in its critical section, no another process is to be permitted to execute its critical sections. Therefore the execution of critical sections through the processes is mutually exclusive in time.