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

Benefits of virtual memory, Q.  When virtual memory is executed in a comput...

Q.  When virtual memory is executed in a computing system there are convinced costs associated with the technique and certain benefits. List the costs as well as the benefits. Is i

Use of c and c++, One reason to learn C and C++ is simply that so much soft...

One reason to learn C and C++ is simply that so much software is written in these languages. A related, butmore fundamental reason, is that C and C++ are relatively low-level, allo

Explain the exitthread function used in the windows nt, Explain the ExitThr...

Explain the ExitThread Function used in the Windows NT ExitThread(ExitCode) The ExitThread( ) call is made to end the currently running thread. If the current thread is th

What is an operating system, What is an operating system? An operating ...

What is an operating system? An operating system is a program that manages the computer hardware. It acts as an intermediate among users of a computer and the computer hardware

Write an equation for this seek time, Q. The accelerating search for descr...

Q. The accelerating search for described in subsequent exercise is typical of hard-disk drives. By contrast floppy disks and several hard disks manufactured before the mid-1980s t

What are the benefits of multiprogramming?, What are the benefits of multip...

What are the benefits of multiprogramming? Responsiveness : Multithreading is an interactive application may permit a program to continue running even if part of it is block

Contiguous-memory allocation, Compare contiguous-memory allocation with pur...

Compare contiguous-memory allocation with pure paging in the following aspects: 1. In support of dynamic memory allocation: most systems allow programs to allocate more memory t

Explain the circumstances under which os use mutexes, Q. Give the reasons ...

Q. Give the reasons why Windows XP, Solaris and Linux implement multiple locking mechanisms. Explain the circumstances under which they use mutexes, spinlocks, semaphores, adaptiv

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