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研究生:劉彥志
論文名稱:在爪哇虛擬機器中於方法回傳時釋放堆積中區域性物件
論文名稱(外文):Freeing Local Objects in Heap upon Method Returning in JVM
指導教授:鍾崇斌
學位類別:碩士
校院名稱:國立交通大學
系所名稱:資訊工程系所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2005
畢業學年度:94
語文別:英文
論文頁數:41
中文關鍵詞:垃圾收集堆積管理區域物件爪哇虛擬機器記憶體受限
外文關鍵詞:Garbage CollectionHeap ManagementLocal ObjectJava Virtual MachineMemory Constrained
相關次數:
  • 被引用被引用:1
  • 點閱點閱:187
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  • 下載下載:8
  • 收藏至我的研究室書目清單書目收藏:1
爪哇虛擬機器(Java Virtual Machine)近來被利用在記憶體受限的嵌入式系統中。然而,在記憶體受限的環境下執行爪哇程式會導致呼叫垃圾收集的次數變多。在最糟的情況下,總執行時間的一半都是在做垃圾收集的動作。而有一些生命週期不會超出配置他之方法的物件,我們稱之為區域物件。所以,如何在方法回傳後掃除該方法之區域物件來減少垃圾收集的頻率就變成記憶體受限系統下的重要課題。然而現存掃除區域的方案是將區域物件放入方法框(Method Frame)中,這會帶來先天上的限制使我們沒辦法掃除所有的區域物件。所以我們將提出一種在堆積(Heap)而非方法框中管理區域物件的機制。他可以讓我們在記憶體極受限的情形下得到比原始爪哇機器好11%的速度效能。
Java Virtual Machine is adopted in embedded memory constrained system recently. However, executing a Java program in memory constrained system will result in more frequent invocation of garbage collection. In worst case, the ratio of garbage collection time to total execution time is about 50%. There are objects whose lifetime will not escape scope of method which allocates it, which is called a local object. So, freeing local objects upon method return to reduce frequency of garbage collection is important in memory constrained system. However, current approach to allocate local objects in stack brings some constraints that we can not free all local objects. So, we propose a mechanism to manage local objects in heap but not stack to free more local objects. Comparing to original Java Virtual Machine, it leads to about 11% speedup to total execution time in extremely memory constrained environment.
摘要 i
ABSTRACT ii
ACKNOWLEDGMENT iii
Table of Contents iv
List of Figures vi
List of Tables vii
Chapter 1 Introduction 1
1.1 Reducing Frequency of Garbage Collection 1
1.2 Existing Methods 2
1.3 Motivation and Objective 2
1.4 Thesis Organization 3
Chapter 2 Background 4
2.1 Java Virtual Machine 4
2.1.1 Class Loader and Method Area 5
2.1.2 Interpreter 5
2.1.3 Java Stack 6
2.1.4 Heap 7
2.1.5 Garbage Collector 8
2.2 Escape Analysis 10
2.3 Stack Allocation 12
2.4 Summary 14
Chapter 3 Design 15
3.1 Design Overview 15
3.2 Allocating Local Objects 16
3.2.1 Data structure to store Local Objects in heap 16
3.2.2 Policy to Allocate Local Objects in heap 19
3.3 Freeing Local Objects upon method return 21
3.4 Cooperation of garbage collector and my design 23
3.5 Summary 25
Chapter 4 Simulation 28
4.1 Evaluation Equation 28
4.2 Simulation Environment 29
4.3 Benchmark 30
4.4 Discussion about minimal size of Local Chunk 31
4.5 Simulation Result 32
4.5.1 Ratio of GC time to total execution time 32
4.5.2 Times of GC in different design 33
4.5.3 Total execution time in different design 34
4.5.4 Overheads 36
Chapter 5 Conclusions 38
References 41
[1] C. E. McDowelt* , “Reducing garbage in Java” Volume 33 , Issue 9 (September 1998) , Pages: 84 - 86 ,Year of Publication: 1998
[2] Tim Lindholm, Frank Yellin “The JavaTM Virtual Machine Specification”. http:// http://java.sun.com/docs/books/vmspec/html/VMSpecTOC.doc.html
[3] Sun Microsystems, Inc , “J2Me Building Blocks for Mobile Devices – White Paper on KVM and the Connected, Limited Device Configuration (CLDC)” 901 San Antonio Road, Palo Alto, CA 94303 USA, 650 960-1300 fax 650 969-9131, May 19, 2000
[4] 探矽工作室著, 深入嵌入式Java 虛擬機器 Inside KVM 學貫行銷股份有限公司出版, 2002[民91]
[5] Joshua Engel, Tim Lindholm, Java Virtual Machine, 1 edition, O'Reilly; (April 1, 1997)
[6] Erik Corry, “Stack Allocation for Object-Oriented Languages” Daimi University of Aarhus, Denmark corry@daimi.au.dk ,May 24, 2004
[7] David Gay, Bjarne Steensgaard, ”Stack Allocating Objects in Java”, Microsoft Technical Report, November 1998
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