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

Explain linked allocation, Linked allocation With linked allocation, ev...

Linked allocation With linked allocation, every file is a linked list of disk blocks; the disk blocks might be scattered anywhere on the disk. The directory has a pointer to th

Define programming fundamentals for client- server developer, Define the Pr...

Define the Programming Fundamentals for Client- Server Developers Coding for client - server enforces good programming fundamentals. In order for applications to become client

Explain about time sharing systems, Q. Explain about Time Sharing Systems? ...

Q. Explain about Time Sharing Systems? Time Sharing Systems Multi-programmed batched systems provide an environment where various system resources (for illustration CP

What is file allocation?, What is File Allocation? The structure that ...

What is File Allocation? The structure that offers the FAT file system its name is the file allocation table . In order to know what this important table does, you should fir

How memory utilization factor shall be computed, How Memory utilization fac...

How Memory utilization factor shall be computed  Memory utilization factor shall be defined as Memory in use/total memory connected

Nachos file system, File System Interface and Implementation The Nachos ...

File System Interface and Implementation The Nachos file system, as distributed, uses a single-level index allocation method for data allocation of files. In the current design,

What is page fault, Problem: a) The CPU can access 2 storage devices di...

Problem: a) The CPU can access 2 storage devices directly. What are these 2 storage devices? b) Define 2 key issues involved in memory management. c) How do processes sha

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

Define throughput, Define throughput? Throughput in CPU scheduling is t...

Define throughput? Throughput in CPU scheduling is the number of processes that are completed per unit time. For long processes, this rate might be one process per hour; for sh

Distinguish among a streams driver and a streams module, Q. Distinguish amo...

Q. Distinguish among a STREAMS driver and a STREAMS module? Answer: The STREAMS driver controls the physical device that could be involved in a STREAMS operation. The STREAMS

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