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

Define the tlsfree(tlsindex) function, Define the TlsFree(TLSIndex) Functio...

Define the TlsFree(TLSIndex) Function This function should be called to free a TLSindex allocated by TlsAlloc. It would be executed when there are no more threads in a process

Explain the resource ownership by platform, Explain the Resource Ownership ...

Explain the Resource Ownership by Platform Ownership of data items may further be complicated by concepts defined in certain operating systems. Each operating system defines "p

Allocating new pages, Processes have valid and invalid entries on their pag...

Processes have valid and invalid entries on their page tables. The valid entries all point to some where "real" (e.g. a physical page, or some portion of disk in case of non-reside

Define the throughput of a system, Define the “Throughput” of a system  ...

Define the “Throughput” of a system  Throughput is Number of programs processed by it per unit time

Memory pages, Applications allocate memory in terms of the number of bytes ...

Applications allocate memory in terms of the number of bytes that they need, but this level of granularity is too ?ne-grained for the operating system to manage the system memory i

List post-installation procedures that need to be performed, Problem: (...

Problem: (a) Based on your experience in setting up Windows 2003 Server operating system, briefly describe the twelve different steps in which the installation is conducted du

How does an operating system make multiprogramming possible, How does an op...

How does an operating system make multiprogramming possible by using single processor?

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

Did Abhinav agree to the initial timeline requested by Rebecca

Operating system, The term Operating System (OS) is often misused. It is co...

The term Operating System (OS) is often misused. It is common, for example, for people to speak of an OS when they are in fact referring to an OS and to a set of additional applica

Define unixware, Define UnixWare UnixWare manages resources at the proc...

Define UnixWare UnixWare manages resources at the process level. Each resource allocated to the application is actually allocated to the process representing the application. C

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