MPI Token Ring

A distributed-systems lab project written in C using the Message Passing Interface (MPI). It demonstrates token-based mutual exclusion by coordinating access to a simulated shared printer across multiple processes.

Overview

The program creates a logical ring of exactly three MPI processes. A single token circulates from one process to the next, allowing only the process holding the token to enter the critical section and use the shared printer.

How It Works

1. Process 0 starts with the token.
2. The token holder accesses and releases the simulated printer.
3. The token is sent to the next process in the ring.
4. After all processes have received it, the token returns to Process 0.

Concepts Demonstrated

• Distributed processes with MPI
• Point-to-point communication using MPI_Send and MPI_Recv
• Token-ring topology
• Mutual exclusion and critical-section coordination
• Process ranks and inter-process synchronization

Requirements

• A C compiler
• An MPI implementation such as Open MPI or Microsoft MPI

Build

mpicc token_ring.c -o token_ring

Run

The current implementation requires exactly three processes:

mpiexec -n 3 ./token_ring

On Windows, run the generated executable as follows:

mpiexec -n 3 token_ring.exe

Project Structure

• token_ring.c — Implements the token-ring simulation and shared-printer coordination.