What is readers-writers problem in OS?

What is readers-writers problem in OS?

Computer ScienceMCAOperating System. The readers-writers problem relates to an object such as a file that is shared between multiple processes. Some of these processes are readers i.e. they only want to read the data from the object and some of the processes are writers i.e. they want to write into the object.

What is readers-writers problem give a solution to readers-writers problem using monitors?

Considering a shared Database our objectives are: Readers can access database only when there are no writers. Writers can access database only when there are no readers or writers.

What is second reader/writer problem?

The second readers-writers problem requires that, once a writer is ready, that writer performs its write as soon as possible. In other words, if a writer is waiting to access the shared data, no new readers may start reading.

How do you implement a solution to the readers-writers problem with the use of semaphores?

The reader processes share the semaphores mutex and wrt and the integer readcount. The semaphore wrt is also shared with the writer processes. mutex and wrt are each initialized to 1, and readcount is initialized to 0. signal(wrt);

Which kind of process has higher priority reader or writer?

From the above problem statement, it is evident that readers have higher priority than writer. If a writer wants to write to the resource, it must wait until there are no readers currently accessing that resource.

How to solve the readers and writers problem?

Three variables are used: mutex, wrt, readcnt to implement solution semaphore mutex, wrt; // semaphore mutex is used to ensure mutual exclusion when readcnt is updated i.e. when any reader enters or exit from the critical section and semaphore wrt is used by both readers and writers Functions for sempahore :

Why is there no reader in the critical section?

Thus, no reader is waiting simply because a writer has requested to enter the critical section. Priority Inversion is a big limitation of semaphores. Their use is not enforced, but is by convention only. With improper use, a process may block indefinitely. Such a situation is called Deadlock.

How does the WRT restrict the entry of writers?

If this reader is the first reader entering, it locks the wrt semaphore to restrict the entry of writers if any reader is inside. It then, signals mutex as any other reader is allowed to enter while others are already reading. After performing reading, it exits the critical section.

Which is an example of a readers problem?

In computer science, the first and second readers-writers problems are examples of a common computing problem in concurrency.