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

Why page sizes always powers of 2, Q. Why page sizes always powers of 2? ...

Q. Why page sizes always powers of 2? Answer: Recall that paging is executed by breaking up an address into a page and offset number. It is most competent to break the address

Explain lru second chance algorithm, Second chance Algorithm When the p...

Second chance Algorithm When the page is chosen the reference bit is checked to see whether it has been referenced before. If that is the case after that it is given a second c

Correct the code for visitor and vehicle portion, Gopher Gallery consists o...

Gopher Gallery consists of a shopping mall and a cart ride that covers the 150 acre habitat. There are m visitors and n single-person vehicles. Visitors stroll around the mall at t

Define a policy for data storage, Produce a referenced four page report whi...

Produce a referenced four page report which describes the possible functionality of the system; similar systems that are out there and different possible approaches to delivering t

Define approaches that require knowledge of the system state, Define approa...

Define approaches that require knowledge of the system state?  Answer: Deadlock detection, Deadlock prevention, Deadlock Avoidance.

Name two differences between logical and physical addresses, Q. Name two di...

Q. Name two differences between logical and physical addresses? Answer: A logical address doesn't refer to an actual existing address rather it refers to an abstract address in

Define program preemption, Define Program preemption The Forced de-allo...

Define Program preemption The Forced de-allocation of the CPU from a program which is executing on the CPU is known as Program preemption

Explain what is semaphores, Explain what semaphores are, their usage, imple...

Explain what semaphores are, their usage, implementation given to avoid busy waiting and binary semaphores. Semaphore definition Usage for mutual exclusion and process synch

Operating system strectures, with the aid of diagrams describe the followin...

with the aid of diagrams describe the following os structures monolithic , layered, client server

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