Date of Award

3-2018

Culminating Project Type

Thesis

Degree Name

Information Assurance: M.S.

Department

Information Assurance and Information Systems

College

Herberger School of Business

First Advisor

Dennis Guster

Second Advisor

Erich Rice

Third Advisor

Balasubramanian Kasi

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

Garbage collection, Apache Tomcat, object strength, web service, YourKit Java Profiler

Abstract

Garbage collection is proving to be an important feature that supports high-performance web services, especially those running data-intensive applications. Due to the use of the object-oriented paradigm, many applications have increasingly opted for the dynamic memory allocation method of assigning their objects in computer memory. During program execution, the application allocates its objects to a memory space called a heap and constantly references these objects within that memory space. With the passage of time, if the objects are not referenced, they become weak/dead to the extent that they can no longer be referenced by an application which allocated them. In such a scenario, the application is required to allocate new objects to a heap in order to continue performing its functions. And, there must be a garbage collection mechanism to remove the dead/weak (unreferenced) objects from the memory heap so that the memory space can be reclaimed and dynamically allocated to other application objects. Java as a Virtual machine, performs memory allocation and reclamation by itself thereby allowing the programmer to concentrate only on the functionality of the application. In other words, the developer is not concerned about how the memory will be managed during the program execution because that will be the duty of the Java language executing on Java Virtual machine.

Therefore, for Java to effectively manage the computer memory, it uses five garbage collection mechanisms which will be explained in detail in the introduction section. Most of the garbage collections are triggered based on the objects’ lifetime predictions set by the developer of the garbage collection algorithms. None or very few consider the strength of the objects that are no longer referenced in the heap. For example, some objects may still be strong enough that they can be referenced by the application but they are collected anyway because they have reached their predicted age threshold.

Garbage collection mechanisms also vary when used in a different framework other than the traditional (standalone) one. For example, garbage collection in distributed systems becomes more complicated as compared to the traditional garbage collection performed in standalone systems. Similarly, garbage collection in a web-service framework has slight differences as compared to the local/standalone systems due to the inclusion of web service technology elements.

In this paper, the goal is to strive to determine the strength of objects that are no longer referenced by an application in a web service as managed by Java-based services; in relation to the performance of a web application.

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