Reference counting, Operating System

Assignment Help:

The idea of reference counting is to maintain, for every object, the total number of references to that object, i.e. the number of "incoming" pointers. Whenever the number of references is zero we know that the object is not accessible through any pointers, and thus it is garbage. Also, whenever we choose to delete some useless object,we have to recursively check that object to see if it contains pointers to other objects; if so, we have decrement the reference counters for those objects as well. One problem of reference counting, though, is how to deal with cycles. Suppose object A points to B, and B points to A. If these objects can only be reached through each other, we have to free them too, even though their counters are not zero! Note that cycles can common inmany data structures; for example, consider a doubly-linked list. The commonly adopted solution to this problem is to run mark-sweep now and then, in order to remove cyclic references, and then run normal reference counting on the rest of the time.


Related Discussions:- Reference counting

What are overlays?, What are over lays? If a large process enters which...

What are over lays? If a large process enters which is huge than the available memory we are able to use overlays. In this we can divide process into pieces .which is recognize

What is virtual file system?, What is virtual file system? A Virtual f...

What is virtual file system? A Virtual file system switch (VFS) or Virtual file system is an abstraction layer   on top of a more concrete file system. The purpose of a VFS

Explain acyclic graph directories and its implementation, Acyclic Graph Dir...

Acyclic Graph Directories In this kind of directory structure the shared directories or files can exist in the file system in two or more places at once. A tree structure excl

Any four types of operating system feature and structure, explain any four...

explain any four types of operating system feature and structure(design)

What are the issues in designing a network-fault tolerance, Fault tolerance...

Fault tolerance : Machine failures, Communication faults, storage device crashes, and decays of storage media must be tolerated by the system to some extent. A fault tolerant sy

Define what is dispatcher, Define what is Dispatcher In the Worker Mode...

Define what is Dispatcher In the Worker Model, it is the task of the Dispatcher to spawn a thread for every client-to-server connection. The Dispatcher acts as the go-between o

Difference between preemptive and nonpreemptive scheduling, Define the diff...

Define the difference between preemptive and nonpreemptive scheduling. State why strict nonpreemptive scheduling is unlikely to be used in a computer center. Preemptive schedul

What inference does recovery in distributed systems, Q. Consider a distrib...

Q. Consider a distributed system with two sites A and B. Consider whether site A can distinguish among the following: a. B goes down. b. The link between A and B goes down.

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