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

Linux kernel components, Example 1.  The diagram illustrating the data stru...

Example 1.  The diagram illustrating the data structures of in-memory VFS objects and on-disk objects and their relationships on slide 24 of the lecture notes OSD.4. This diagram i

What is the use of inter process communication, What is the use of inter pr...

What is the use of inter process communication. Inter process communication gives a mechanism to allow the co-operating process to communicate with each other and synchronies t

Explain memory management using buddy sustem, MEMORY MANAGEMENT USING BUDDY...

MEMORY MANAGEMENT USING BUDDY SUSTEM Here we are dividing the memory as powers of two as well as we are selecting the space which is smallest but large enough to hold a process

Write about critical regions and monitors, Write about critical regions and...

Write about critical regions and monitors. Critical region definition Monitor definition Implementation of the conditional-region construct Syntax of monitor Monito

Demand paging, Demand paging gives that pages could only be brought into ...

Demand paging gives that pages could only be brought into memory if the running process acts them. This is usually referred to as lazy evaluation as only those pages operated by

What problems arise if the directory is a general graph, What problems aris...

What problems arise if the directory structure is a general graph? Searching for a particular file may result in searching the similar directory many times. Deletion of the fil

Shared stack is used for parameter passing, Q. What protection problems may...

Q. What protection problems may occur if a shared stack is used for parameter passing? Answer: The contents of the stack could be conciliation by other process(es) sharing th

Explain activities of an os in regard to file management, What are the five...

What are the five major activities of an operating system in regard to file management? The creation and deletion of files The creation and deletion of directories The s

Least-recently used, LRU evicts the page which was last accessed the farthe...

LRU evicts the page which was last accessed the farthest into the past of any page resident in physical memory, i.e. the least-recently used page. LRU approximates OPT when the rec

Task decomposition and data decomposition, Discuss the concepts of  task de...

Discuss the concepts of  task decomposition  and  data decomposition  within the context of parallel programming. Parallel programming or parrelel computing is the simultaneo

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