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

Steps to run a program on a completely dedicated machine, Q. List the four ...

Q. List the four steps that are essential to run a program on a completely dedicated machine. Answer: a) Reserve machine time b) Manually load program into memory c)

Case studies, Did Abhinav agree to the initial timeline requested by Rebecc...

Did Abhinav agree to the initial timeline requested by Rebecca

Explain root partition, Explain root partition The root partition,which...

Explain root partition The root partition,which have the operating-system kernel and potentially other system files, is mounted at boot time. In successful mount operation, ope

What are batch systems, What are batch systems? Batch systems are quite...

What are batch systems? Batch systems are quite appropriate for implementing large jobs that need little interaction. The user can submit jobs and return later for the results.

How can the deadlock be prevented-safe state, How can the deadlock be preve...

How can the deadlock be prevented-Safe State Safe state : A state is safe if the system is able to allocate resources to each process in some order and still avoid deadlock.

Differences among user-level threads and kernel-level thread, Q. What are t...

Q. What are two differences among user-level threads and kernel-level threads? Under what situations is one type better than the other? Answer: (1) User-level threads are un

Write pseudo code to implement the pthread create wrapper, Write pseudo cod...

Write pseudo code to implement the pthread_create wrapper of the Tern memoizer. Note you need to describe your data structure for maintaining deterministic thread IDs. In addition,

Operating systems structures, with the aid of diagrams describe the followi...

with the aid of diagrams describe the following OS structure monolithic,layered and client server.

What effect would updating a few byte on the one page, Q. What is the effe...

Q. What is the effect of permitting two entries in a page table to point to the same page frame in memory? Describe how this effect could be used to decrease the amount of time ne

What are the allocation methods of a disk space, What are the allocation me...

What are the allocation methods of a disk space? Methods of allocating disk space which are widely in use are a. Contiguous allocation b. Linked allocation c. Indexed

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