Mark-sweep, Operating System

Assignment Help:

The objects that a program can access directly are those objects which are referenced by local vari-ables on the processor stack, or by any global/static variables that refer to objects, or by variables in CPU registers. In the context of garbage collection, these variables are called the roots. An object is indirectly accessible if it is referenced by a ?eld in some other (directly or indirectly) accessible object. An accessible object is said to be live. Conversely, an object which is not live is garbage.

Note that heap objects which are live are indirectly accessible from the roots or other heap objects. The idea of mark-sweep is relatively straightforward. We start at the roots, and recursively visit every object accessible through pointers, marking them as live. At the end of the process, every thing not marked is considered garbage and will be deleted. Notice that mark-sweep can perform lazy garbage collection, in the sense that it does not necessarily need to remove the garbage immediately.

Note thatmark-sweep does not clean upmemory which is allocated, but simply never used. Also, periodically we have to visit all objects recursively, starting from the roots. For a large program, this will be slow. This is a problem with the traditional mark-sweep algorithm.


Related Discussions:- Mark-sweep

Bounded and unbounded buffer, Ask question #Minimum 100 difference between ...

Ask question #Minimum 100 difference between bounded and unbounded buffer words accepted#

What is directory, What is Directory? The device directory or simply ca...

What is Directory? The device directory or simply called as directory records information-such as name, location, size, and type  for all files on that certain partition. The d

Custom memory allocation, Some people write custom memory allocators to mee...

Some people write custom memory allocators to meet their speci?c needs. Although this is not needed for most of the applications, it is also not uncommon. The goal, of course, is t

What is banker''s algorithm, What is banker's algorithm? Banker's algor...

What is banker's algorithm? Banker's algorithm is a deadlock avoidance algorithm that is applicable to a resource-allocation system with multiple examples of each resource type

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

Explain additional-reference-bits algorithm, Additional-reference-bits algo...

Additional-reference-bits algorithm We can keep an 8-bit byte for every page in a table in memory. The operating system shifts the reference bits right 1 bit, discarding the lo

Problem, whats the problem in two state model ?

whats the problem in two state model ?

Explain combined ult/klt approaches, COMBINED ULT/KLT APPROACHES Idea i...

COMBINED ULT/KLT APPROACHES Idea is to merge the best of both approaches Solaris is an illustration of an OS that combines both ULT and KLT  Thread creation complete i

What are the services provided by the operating systems, What are the servi...

What are the services provided by the operating systems?  Program Development It provides a variety of services and facilities, such as debuggers and editor, to help the

What is long-term, What is long-term, medium-term, short-term? In a bat...

What is long-term, medium-term, short-term? In a batch system many processes are submitted than are able to be executed immediately. These processes are reel to a mass storage

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