Conservative garbage collection, Operating System

Conservative GC can be used for languages such as C and C++, which were not explicitly designed for garbage collection. This is a non-copying technique. A conservative garbage collector is one that, instead of knowing the exact location of each object, discovers the set of live objects by scanning a region of memory, looking for areas that may be objects. Because C and C++ allow casting, anything that can hold a pointer could conceivably be a pointer, such as an unsigned long which is cast as a pointer, or a ?oating-point type which is cast as a pointer, etc. Conservative GC more or less uses the "duck test", paraphrased here as "if it looks like a pointer and acts like a pointer, it's probably a pointer". Starting from the roots, we can ?nd all objects which look like pointers, and the objects to which they would point if they were in fact pointers, and mark those objects as live. By doing this, we can provide garbage collection to languages which otherwise would not support it.

The possible objects found may or may not actually be objects, but we are ensured that all live objects referred to from that particular area are found by the garbage collector. Since we must discover the areas that might be objects, we also have to know how to identify pointers; usually, if something looks like a pointer, we assume it is a pointer. Then, conservative GC traces through those "pointers", marking everything that is still live.

Some of the drawbacks of this method are: 1) areas of memory that look like pointers to objects, but aren't, cause garbage objects to be retained as long as the fake pointer exists; this increases memory usage of the garbage collector, and can cause other limited resources to be exhausted; and 2) the methods of ?nding exactly which areas to trace aren't always portable.

Posted Date: 3/13/2013 3:01:13 AM | Location : United States







Related Discussions:- Conservative garbage collection, Assignment Help, Ask Question on Conservative garbage collection, Get Answer, Expert's Help, Conservative garbage collection Discussions

Write discussion on Conservative garbage collection
Your posts are moderated
Related Questions
When a program issues a memory load or store operation, the virtual addresses (VAs) used in those operations have to be translated into "real" physical memory addresses (PAs). This

Q. Explain the booting process for a Windows XP system? Answer: (1) Since the hardware powers on the BIOS begins executing From ROMand loads as well as executes the bootstrap

Define entry section and exit section. The critical section problem is to design a protocol that the processes can use to cooperate. Every process must request permission  to e

what is an operating system?

how to differentiate scheduling algorithms?

There is a process bloacked by a semaphore and no other process in the ready queue, can the blocked process get back to the ready queue without the semsignal() function?

. A paper mill produces two grades of paper viz., X and Y. Because of raw material restrictions, it cannot produce more than 400 tons of grade X paper and 300 tons of grade Y paper

Briefly discuss on real-time scheduling? It is divided into two types.  Hard real-time systems are needed to complete a critical task within a guaranteed amount of time. T

WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF DUAL MODE OPERATION OF OPERATING SYSTEM>?

What is co-operating scheduling? CPU scheduling decisions may possibly place under the following four circumstances: 1.      When process switches from the running state to