Examples Of Mutual Exclusion In Distributed Computing
1375 Words6 Pages
Ministry of High Education
Mutual Exclusion in Distributed Computing
Done by: Rabaa Khalifa Thaniyan Alamri Afrah Saif Ahmed Albusaidi
Submitted to: Dr. Shaikh A Khalique
Distributed system is a set of processes connected by communications links. To achieve collaborative tasks by a set of processes, many distributed algorithms have been proposed. The problem of mutual exclusion is one of fundamental problem in distributed systems, which are required for example, update of shared object consistently. By distributed mutual exclusion, it is guaranteed that the number of processes which updates the object is at most one at any time.
Mutual exclusion in computer science is the…show more content… • Livens: progress (if no one holds the lock, a processor requesting it will get it).
• Fairness: bounded wait and in-order.
2- Minimize message traffic.
3-Minimize synchronization delay
• Switch quickly between processes waiting for lock
Mutual exclusion in single computer vs distributed system
In single computer system, the shared resource is available in the shared memory and the mutual exclusion problem is solved using the shared variables.
In the distributed systems the shared resource and users are distributed and there is no shared memory. Shared variables are does not exist in distributed system.
The mutual exclusion problem is more complex when it is in distributed system in comparison with the single computer system. This is because there is no shared memory and no common physical clock. Also, the message delay is unpredictable therefore the distributed system is left without complete knowledge of system state.
Mutual Exclusion Algorithms Requirement
The main purpose of the mutual exclusion algorithm is to maintain exclusion i.e. it make sure that only one request access the CS (critical section) at a time. The below characteristics considered to be important in a mutual exclusion…show more content… After the CS finish executing one request, the next request is started and so on. The site is rarely found to be in an idle state.
Distributed Mutual Exclusion solution
In the distributed mutual exclusion, a site called the control site is responsible to organize the queue of requests and to grant permissions from the CS to execute requests. In order for the site to be executed, it has to send a request to the control site and the control site would ask the CS for executing permission. The process needs three messages per execution. The control site acts like a broker between the sites and the CS.
Even though, the control site solution sound a good solution for the distributed mutual exclusion but there is nothing perfect and disadvantages would always be there. The control site method has a single point of failure. The control site could be overloaded with the requests which would cause the process to slow down. Another disadvantage is the synchronous delay which increases because the site has to send request to the control site and the control site ask the CS for permission, which for sure would increase the delay of