3.11 - Reader Writer Problem using Semaphore

Описание: This video explains What is Reader Writer Problem, Solution of readers/writers problem using Semaphores
Learn Reader Writer Problem using Semaphore with animation and examples.

Problem: There is a shared resource which should be accessed by multiple processes. There are two types of processes in this context. They are reader and writer. Any number of readers can read from the shared resource simultaneously, but only one writer can write to the shared resource. When a writer is writing data to the resource, no other process can access the resource. A writer cannot write to the resource if there are non zero number of readers accessing the resource at that time.
Solution: 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.
Here, we use one mutex m and a semaphore w. An integer variable read_count is used to maintain the number of readers currently accessing the resource. The variable read_count is initialized to 0. A value of 1 is given initially to m and w.
Instead of having the process to acquire lock on the shared resource, we use the mutex m to make the process to acquire and release lock whenever it is updating the read_count variable.

Operating System PPTs with animation is available here: http://www.darshan.ac.in/DIET/CE/GTU-...

This video is recorded by Prof. Firoz Sherasiya ([email protected], +91-9879879861) at Computer Engineering Department of Darshan Institute of Engineering & Technology, Rajkot as per GTU Syllabus.

GTU - Computer Engineering (CE) - Semester 4 - 2140702 – Operating System- Interprocess Communication- Solution to the Reader-Writer problem using Semaphores

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