Read-write locks, Operating System

Assignment Help:

Consider a large web-based database. In some sense, Google is sort of like this. There might be many users who want to read from the database, but only a few users who are allowed to write to the database. If we use standard locks to control access to the database, the application will be much slower than it could be with a more clever type of lock.

Suppose we have one object that is shared among several threads. Suppose also that each thread is either a reader or a writer. Readers only read data but never modify it, while writers read and modify data. If we know which threads are reading and which ones are writing, what can we do to increase concurrency?

First, we have to prevent two writers from writing at the same time. In addition, a reader cannot read while a writer is writing. There is no problem, however in allowing lots of readers to read at the same time. Read-write locks achieve this, and can greatly improve performance for this sort of application.

Note that the lock is the same for both readers andwriters (called 'rw' in the slides), but the readers use an rlock() on the lock and writers use a wlock() on the same lock. Writers requesting a wlock() will have to wait until all readers and writers have released the lock. Readers requesting a rlock() can acquire it even if other readers are holding the lock. Readers however will still have to wait until any writer holding the lock releases the lock.


Related Discussions:- Read-write locks

Explain and differentiate programmed and interrupt i/o, Question 1 Explain...

Question 1 Explain the structure of operating system in detail Question 2 Explain the following scheduling algorithm                                     1) First come Firs

What resources are utilized when a thread is created, Q. What resources are...

Q. What resources are utilized when a thread is created? How do they vary from those used when a process is created? Answer: For the reason that a thread is smaller than a pr

Explain three major components of page-fault service time, We are faced wit...

We are faced with three major components of the page-fault service time. 1. Service the page-fault interrupts. 2. Read in the page. 3. Restart the processes.

Producer-consumer, The general idea of a producer-consumer architecture is ...

The general idea of a producer-consumer architecture is related to building a pipeline of threads, similar to the web spider from Project 2. Each step of the processing will now be

Explain the resource ownership by platform, Explain the Resource Ownership ...

Explain the Resource Ownership by Platform Ownership of data items may further be complicated by concepts defined in certain operating systems. Each operating system defines "p

Explain objectives of the file management system, Problem: a) Define a ...

Problem: a) Define a ‘file' and list the objectives of the file management system. b) List the ways in which programs access files and determine for what file types you woul

Fibonacci sequence, #questionThe Fibonacci sequence is the series of number...

#questionThe Fibonacci sequence is the series of numbers 0,1,1,2,3,5,8,… Formally, it can be expressed as: fib0 = 0 fib1 = 1 fibn = fib n-1 + fib n-2 Write a C program u

Android application development using java, This is a group project as desc...

This is a group project as described in the 'AssignmentDescription.pdf' file. I am doing a sub project which is "sub project Mobile application. Android or Apple based. Turn based

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd