Mutual exclusion in a distributed system


A key principle of distributed systems is mutual exclusion, which prevents simultaneous operations or node locations from concurrently using common assets or crucial areas. When various procedures attempt to gain access to an identical asset at once, disputes, racial conditions, and discrepancies may result.

Due to the absence of storage and the possibility of connection interruptions, errors, and node-to-node difficulties with communication and mutual exclusion turns more difficult in distributed systems. For achieving mutual exclusion in distributed systems, many techniques and procedures were established.

In this article, we will be exploring the two main approaches, the various types, and use cases of Mutual Exclusion in a distributed system.

Approaches of Mutual Exclusion in a distributed system

The following are two approaches to Mutual exclusion in a distributed system.

  • Centralized Approach − In this method, accessibility to the communal resource is granted and managed by an underlying organizing entity, frequently referred to as the administrator or lock manager. prior to obtaining the most important section, methods or nodes have to ask the person in charge for authorization. The coordinator manages a list of pending inquiries and allows just one procedure at one point to make use of the resource. The coordinator's reliability and accessibility must be guaranteed because if it fails, everything in the system will suffer.

  • Distributed Approach − Without using a centralized coordinator, methods or nodes work together in the distributed approach to set up exclusion between themselves. There are many methods for distributed mutual exclusion, including Ricart-Agrawala, Maekawa, and Lamport's Bakery algorithms. For these methods to decide which programs should gain access to the crucial component first, a collection of regulations and exchanges of messages between them are typically used. Dealing with a network of things delays, and errors, and preserving reliability between the engaging procedures is an important difficulty with these algorithms.

Use Cases of Mutual Exclusion in distributed systems

Below are a few scenarios involving real-time distributed systems in which mutual exclusion is essential −

  • Database Systems − Several users or programs can connect to a single database at once in a distributed database system. While carrying out write operations or crucial file operations, mutual exclusion is required for preserving information consistency and ethical behavior. To make certain that just a single consumer is able to alter the shared information at once distributed locking techniques are implemented. These techniques include two stages locking and timestamp-requesting procedures.

  • File Sharing Systems − Several people may concurrently try to obtain or alter an identical file in file systems. Mutual exclusion is necessary to guarantee that just one individual is able to write a record at the same time in order to avoid disputes and data fraud. To regulate access and uphold mutual exclusion, distributed file-locking rules or distributed decision-making techniques may be used.

  • Distributed Resource Scheduling − Several operations or procedures could battle in a distributed computing system for materials like memory, processor, or network bandwidth. To guarantee that just one assignment is able to make use of a resource at once, mutual exclusion is essential. To manage access and avoid resources dispute, distributed scheduling techniques like distributed keys or allocation of resources rules are implemented.

  • Distributed Transaction Processing − In order to guarantee the integrity and uniformity of an operation in a distributed system for transaction processing in which numerous nodes or databases are involved, mutual exclusion is required. Mutual exclusion The processes are incorporated into distributed transaction procedures, including a two-phase commit or a three-phase commit, to organize the operation carried out throughout various nodes and guarantee that all nodes concur on the choice of whether about committing or rollback.

Types of Mutual Exclusion

Diverse mutual exclusion mechanisms are employed in distributed systems. Below are a few typical examples −

  • Lock-Based Mechanism − Locks are used in lock-based mechanisms that impose mutual exclusion. Prior to obtaining a shared asset or essential section, procedures or nodes obtain a lock. Locks can be either divulged (more than a single procedure may obtain the lock at once, but no restricted lock can be obtained) or restricted (just a single procedure can gain the lock at a time). The provisioning and releasing of locks among distributed nodes are coordinated by distributed lock managers.

  • Token-Based Mechanism − In order to regulate the availability of materials, token-based mechanisms depend on the transfer of tokens within operations. The key component of communal assets can only be accessed by an operation that is in possession of the token. After completing its task, the process transfers the token in an established sequence to the following eligible procedure. Token passing maintains mutual exclusion by making sure just a single procedure has access to the material at once.

  • Time-Stamped Mechanism − The chronological sequence of gaining access to communal assets is determined by timestamp-based mechanisms, which allocate distinct records of the timestamp for operations or transactions. While methods that have shorter timestamps have to wait, those that have greater timestamps have importance and are able to use the resource in question right away. Operations are able to utilize materials in an ordered and mutually reinforcing behavior thanks to timestamp-requesting rules and regulations.

  • Quorum-Based Mechanism − The idea of quorums, which are segments of nodes in a distributed system, is used by quorum-based mechanisms. A method needs approval from a majority of nodes in order to gain entry to a resource that is shared. In order to achieve mutual exclusion, quorum-based protocols like the Quorum Consensus Protocol (QCP) or the Paxos algorithm guarantee only those methods with overlaid quorums can access the resource simultaneously.


Distributed systems may guarantee accuracy and honesty, preserve consistency in data, avoid disputes, and facilitate simultaneous utilization of communal assets by guaranteeing mutual exclusion. In order to attain the ideal degree of synchronization and collaboration between distributed processes or nodes, the particular mutual exclusion mechanism ought to be carefully determined to correspond to the system's specifications and limitations.

Updated on: 17-Jul-2023

1K+ Views

Kickstart Your Career

Get certified by completing the course

Get Started