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

Explanation of computer clustering and benefits, The CTO is still impressed...

The CTO is still impressed with your work. He just came back from a technology exposition where he heard about computer clusters. All he knows is that they are the big thing for bu

Explain deadlock avoidance, Deadlock Avoidance It's a method to evade ...

Deadlock Avoidance It's a method to evade deadlock by careful resource scheduling. This approach to the deadlock problem foresees deadlock before it actually occurs. This a

What are the common strategies to select a free hole, What are the common s...

What are the common strategies to select a free hole from a set of available holes? The most common methods are a. First fit b. Best fit c. Worst fit

Explain fixed partitioning techniques, FIXED PARTITIONING In a fixed p...

FIXED PARTITIONING In a fixed partitioning, the operating system inhabiting some fixed portion of main memory is available for use of multiple processes -Using fixed partit

Explain the worker model, Explain the Worker Model The Worker Model of ...

Explain the Worker Model The Worker Model of client-server application architecture provides a very good understanding of threads and their power to the developer. This exercis

Explain process scheduling, Explain Process scheduling Process scheduli...

Explain Process scheduling Process scheduling consists of the subsequent sub-functions: 1.      Scheduling : Selects the process to be implement next on the CPU 2.      D

What are the requirements for a swapper to work, The swapper work s on t...

The swapper work s on the biggest scheduling priority. Initially it will look for any sleeping process, if not get then it will see for the ready-to-run process for swapping. Bu

Find the optimal solution and optimal value, Find the optimal solution and ...

Find the optimal solution and optimal value of the following linear program. Use both (a) the enumerating the corner points method and (b) the iso-profit line method. Also identify

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