6.1 Mutual Exclusion in Distributed Systems

DISTRIBUTED SYSTEM NOTES,IOE,TU,BCA

MUTUAL EXCLUSION IN DISTRIBUTED SYSTEM

Mutual exclusion in a distributed system is a fundamental problem where multiple processes or nodes need to coordinate access to shared resources in such a way that only one process can access the resource at a time. This ensures that concurrent processes do not interfere with each other, which is critical for maintaining data consistency and system stability. Here's a detailed look at the problem and some common solutions:

The Problem

In distributed systems, processes run on different machines and communicate via a network. Unlike centralized systems where mutual exclusion can be easily managed using locks or semaphores, distributed systems face additional challenges:

• No shared memory: Processes cannot rely on shared memory for coordination.
• Communication delays: Network latency can cause delays and uncertainties in message delivery.
• Failure handling: Processes and communication links can fail, complicating coordination.

Requirements

To solve the mutual exclusion problem, the following requirements must be satisfied:

• Mutual Exclusion: Only one process can access the critical section (shared resource) at any given time.
• Progress: If no process is in the critical section, then the processes that want to enter it should be able to do so without unnecessary delays.
• Fairness: Every request should eventually be granted, ensuring no process experiences indefinite waiting (starvation).