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

Dynamic memory management, Usually memory is allocated from a large pool of...

Usually memory is allocated from a large pool of unused memory area called the heap. In C++, dynamic allocation/deallocation must be manually performed using commands like malloc,

Explain the procedure for handling the page fault, The procedure for handli...

The procedure for handling the page fault is as follows 1. We check the internal table to verify whether the reference was valid or invalid. 2. If the reference was invalid,

What are the objectives of operating system?, What are the objectives of op...

What are the objectives of operating system? Objectives of OS 1.      Convenience: An OS makes a computer more suitable to use. 2.      Efficiency : An OS allows t

Most-recently used algorithm, Evicting the most-recently used (MRU) page do...

Evicting the most-recently used (MRU) page does very well on LRU's worst case. In general, however, MRU is a bad idea, since many programs exhibit temporal locality in their memory

Embedded systems design or hardware design, You have been requested by your...

You have been requested by your Senior Engineer to design an Engine Control Unit (ECU) and prepare a report detailing your proposed solution. The client requires a design for a mic

What is two-level directory, What is Two-level directory In the two-lev...

What is Two-level directory In the two-level directory structure every user has own user file directory (UFD). When a user jobs begins or a user logs in, the system's master fi

Why system calls have to be implementing by a interpreter, Q. What system c...

Q. What system calls have to be implementing by a command interpreter or shell in order to start a new process? Answer: In the UNIX systems a fork system call followed by an ex

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