Starve-Free-Readers-Writers-Problem

The Readers-Writers problem is a classical computing problem in the field of concurrency and synchronization, wherein a resource like a database, file, storage area etc. is being accessed by multiple processes concurrently. Each of these processes has a critical section where it is accessing the resource for reading or writing. If the resource is being accessed by a writer process, no other reader or writer process may access it. While, if it is being accessed by a reader resource, other reader processes may access it, but no writer can access it.

Semaphores or monitors can be used to solve the Readers-Writers problem without conflicts. The well-known solutions for the Readers-Writers problem raise the issue of starvation of either the Readers or the Writers. The given solution for the problem solves the issue of starvation.

Data Structures Used

The given pseudocode used a FIFO queue for the processes which are waiting currently. A new structure PCB (Process Control Block) has been defined. It contains details about each process. Semaphore structure has been used to implement semaphores.

Files

1. PCB.pseudo - It contains the declaration of the Process Control Block (PCB) data structure.
2. queue.pseudo - It contains the declaration of the Queue data structure used.
3. semaphore.pseudo - It contains the declaration of semaphore data structure.
4. global_variables.pseudo - It contains the declaration of all global variables.
5. reader.pseudo - It refers to the code for readers.
6. writer.pseudo - It refers to the code for writers.

References

1. Operating System Concepts (Ninth Edition), Silberschatz, Galvin, Gagne
2. Faster Fair Solution for the Reader-Writer Problem