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

Memory pages, Applications allocate memory in terms of the number of bytes ...

Applications allocate memory in terms of the number of bytes that they need, but this level of granularity is too ?ne-grained for the operating system to manage the system memory i

What are race conditions?, What are race conditions? Race conditions ar...

What are race conditions? Race conditions are problems that take place due to the sharing of the same file by several processes. In such a case none of the processes is able to

Identifying parallelism, Identifying parallelism A formal way to identi...

Identifying parallelism A formal way to identify parallelism in an activity is to draw a task dependence graph in a directed graph in which each vertex represents a task to

Write in brief on unix file structure, Write in brief on UNIX file structur...

Write in brief on UNIX file structure. UNIX considers every file to be a sequence of 8-bit bytes no interpretation of these bits is made by the operating system. This system pr

Difference between preemptive and nonpreemptive scheduling, Define the diff...

Define the difference between preemptive and nonpreemptive scheduling. State why strict nonpreemptive scheduling is unlikely to be used in a computer center. Preemptive schedul

Explain important fuction of virtual file system, Virtual File System serve...

Virtual File System serves two important functions. 1. It divides file-system-generic operations from their execution by defining a clean VFS interface. 2. The VFS is based

What resources are utilized when a thread is created, Q. What resources are...

Q. What resources are utilized when a thread is created? How do they vary from those used when a process is created? Answer: For the reason that a thread is smaller than a pr

Business, why some companies do not pay sufficient attention to staff induc...

why some companies do not pay sufficient attention to staff induction

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