hint hint : do i necessarily only need to use one semaphore?)Ĭounting semaphore: A semaphore with more than one value. (Think about how else one could use semaphores to achieve mutual exclusion. Now, is it possible to have greater concurrency? Depends on the critical sections. So each thread is using the same semaphore to provide mutual exclusion for its two critical sections. The mutual exclusion is quite simple as well - m1 and m2 cannot enter the critical section at the same time. Public static Semaphore Bouncer //constructor Here is a very pedagogic example in C# :-) using System For example, to limit the number of simultaneous calls to a database in an application. It's simply a way to limit the number of consumers for a specific resource. If the club is full no one is allowed to enter, but as soon as one person leaves another person might enter. There are a dedicated number of people that are allowed in the club at once. Semaphores may lead to a priority inversion where low priority processes may access the critical section first and high priority processes later.Think of semaphores as bouncers at a nightclub.This happens because the wait and signal operations prevent the creation of a structured layout for the system. Semaphores are impractical for last scale use as their use leads to loss of modularity.Semaphores are complicated so the wait and signal operations must be implemented in the correct order to prevent deadlocks. ![]() Some of the disadvantages of semaphores are as follows −
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