Reference counting, Operating System

Assignment Help:

The idea of reference counting is to maintain, for every object, the total number of references to that object, i.e. the number of "incoming" pointers. Whenever the number of references is zero we know that the object is not accessible through any pointers, and thus it is garbage. Also, whenever we choose to delete some useless object,we have to recursively check that object to see if it contains pointers to other objects; if so, we have decrement the reference counters for those objects as well. One problem of reference counting, though, is how to deal with cycles. Suppose object A points to B, and B points to A. If these objects can only be reached through each other, we have to free them too, even though their counters are not zero! Note that cycles can common inmany data structures; for example, consider a doubly-linked list. The commonly adopted solution to this problem is to run mark-sweep now and then, in order to remove cyclic references, and then run normal reference counting on the rest of the time.


Related Discussions:- Reference counting

Elimination of common sub expression - code optimizatin, Elimination of com...

Elimination of common sub expression during code optimization An optimizing transformation is a rule for rewriting a section of a program to enhance its execution efficiency wi

What are the three main activities of an operating system, What are the thr...

What are the three main activities of an operating system in regard to memory management? Keep track of which parts of memory are now being used and by whom. Decide which pr

What is external fragmentation?, What is external fragmentation? As pro...

What is external fragmentation? As process are removed from and loaded to the memory free memory space is bracken into pieces .external fragmentation take place when enough mem

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

Life of a page, Suppose your process starts up, and allocates some memory w...

Suppose your process starts up, and allocates some memory with malloc(). The allocator will then give part of a memory page to your process. The OS then updates the corresponding p

Explain about spooling, Q. Explain about Spooling? Acronym for simu...

Q. Explain about Spooling? Acronym for simultaneous peripheral operations on line. Spooling denotes to putting jobs in a buffer, a special area in memory or on a disk where

Operating systems structures, with the aid of diagrams describe the followi...

with the aid of diagrams describe the following OS structure monolithic,layered and client server.

Networking sockets with the use of shared memory, Q. Compare the utilizatio...

Q. Compare the utilization of networking sockets with the use of shared memory as a mechanism for communicating data between processes on a single computer. What are the merits of

What is the hardware support required to implement paging, What is the hard...

What is the hardware support required to implement paging? Each operating system has its own techniques for storing page tables. The majority allocates a page table for each pr

List out the advantages of windows 2000 file management, List out the advan...

List out the advantages of windows 2000 file management. Permits detailed security for individual folders and files. Built-in granular compression capabilities

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