Operating System Questions
A semaphore is a synchronization tool used in operating systems to control access to shared resources and ensure mutual exclusion. It is a variable that can take on integer values and supports two main operations: wait (P) and signal (V).
In process synchronization, a semaphore is used to coordinate the execution of multiple processes or threads. When a process wants to access a shared resource, it first checks the value of the semaphore. If the value is positive, the process can proceed and decrement the semaphore value by one (P operation). If the value is zero or negative, the process is blocked and put into a waiting state until the semaphore value becomes positive.
When a process finishes using the shared resource, it signals the semaphore by incrementing its value by one (V operation). This allows other waiting processes to proceed and access the resource.
By using semaphores, processes can synchronize their execution and avoid conflicts when accessing shared resources, ensuring that only one process can access the resource at a time.