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

Three conditions that solution for critical section problem, What are three...

What are three conditions that a solution for the critical section problem must satisfy? The three conditions are as following:- a)      Mutual exclusion :- if a process is

What is the mfd, What is the MFD? UFD? How are they related? MFD is mas...

What is the MFD? UFD? How are they related? MFD is master-file directory, which points to the UFDs. UFD is user-file directory, which points to each of user's files.

What is the basic approach of page replacement, What is the basic approach ...

What is the basic approach of page replacement? If no frame is free is available, find one that is not presently being used and free it. A frame can be freed by writing its con

Explain hierarchical paging, Hierarchical paging Single way is to use a...

Hierarchical paging Single way is to use a two-level paging algorithm, in which the page table itself is also paged. A logical address is separated into a page number and a pag

#title:cs604, Consider a scenario of post mailbox, there are two processes ...

Consider a scenario of post mailbox, there are two processes named sender S and receiver R. Both processes can communicate with each other by name along with message. You need to I

Define instance, Define Instance. An instance is an administrative unit...

Define Instance. An instance is an administrative unit in which components of R/3 systems giving one or more services are grouped together.  The services offered by a case are

Explain medium term scheduling, Medium term scheduling This is componen...

Medium term scheduling This is component of the swapping function. Usually the swapping in decision is based on the need to manage the degree of multiprogramming. At a system t

Unix, UNIX Shell and History feature. 1.Creating a child process. 2.Creatin...

UNIX Shell and History feature. 1.Creating a child process. 2.Creating a history feature. With the notes under code. Its exactly "programming project 1 - Unix Shell and History Fea

How does dma raise system concurrency, Q. How does DMA raise system concurr...

Q. How does DMA raise system concurrency? How does it make difficult hardware design? Answer: DMA increases system concurrency by allowing the CPU to perform tasks while the

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