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

search tree generated by hill-climbing search, Show the search tree genera...

Show the search tree generated by Hill-Climbing search (text figure 4.2, page 122; or Local Search lecture, slide 6) for each of the two heuristics (a) and (b) applied to the follo

What are the issues in designing a network-scalability, Scalability : ...

Scalability : Scalability is the competence of the system to adapt to increased service load. A scalable system will respond more gracefully to increased load than a non-sc

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

Define unix device driver, Define UNIX device driver The UNIX device dr...

Define UNIX device driver The UNIX device driver is structured into two halves called top half and bottom half

Convert the hex to binary, Convert the following from hex to binary and dra...

Convert the following from hex to binary and draw it on the memory map.     RAM    = 0000 -> 00FF     EPROM = FF00  -> FFFF Answer:   0000  0000 0000  0000 (0)    RAM sta

Explain general graph directory, General graph directory The serious pr...

General graph directory The serious problem with using an acyclic-graph structure is ensuring that there are no cycles. When we insert links to an existing tree-structured dire

What are batch systems?, What are batch systems? Early computers were p...

What are batch systems? Early computers were physically huge machines run from a console. The general input devices were card readers and tape drivers. The common output device

What is the cache coherency problem, Question: (a) Modern processors op...

Question: (a) Modern processors operate in one of two modes: one for the operating system and one for applications. What is the purpose of having these two modes? What are

What is time-stamping, time-stamping It is a method proposed by Lampor...

time-stamping It is a method proposed by Lamport, used to sequencing events in a distributed machine without the use of clocks. This process is intended to order events consis

What advantages are there to this two-level directory, What advantages are ...

What advantages are there to this two-level directory? Users are isolated from each other. Users have more freedom in choosing file names.

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