Averroes: Letting go of the library!

Transcription

1 Workshop on WALA - PLDI 15 June 13th, 2015

2 public class HelloWorld { public static void main(string[] args) { System.out.println("Hello, World!"); 2

3 public class HelloWorld { public static void main(string[] args) { System.out.println("Hello, World!"); ~ 8 seconds ~ 600 MB of memory > 900 reachable methods > 1,700 call edges 3

4 Hello, World! 4

5 Partial-Program Analysis 5

6 Partial-Program Analysis I'd like to ignore library code ignore non-application program elements (e.g., system libraries)? what about callbacks? this would be unsound but better than nothing whole-program analysis always pulls in the world for completeness. The problem is that the world is fairly large I am NOT interested in those 6

7 Partial-Program Analysis? 7

8 Ideal Call Graph 8

9 Ideal Call Graph Whole-Program Call Graph 9

10 Incomplete Call Graph (unsound) Ideal Call Graph Whole-Program Call Graph 10

11 Incomplete Call Graph (unsound) Ideal Call Graph Whole-Program Call Graph Conservative Call Graph (highly imprecise) 11

12 Conservative Assumptions m(){ Analyzed Code... call method? c.center = new Point(0,0); modify field create object 12

13 Incomplete Call Graph (unsound) Partial-Program Call Graph Ideal Call Graph Whole-Program Call Graph Conservative Call Graph (highly imprecise) 13

14 The Separate Compilation Assumption 14

15 The Separate Compilation Assumption All of the library classes can be compiled in the absence of the application classes. 15

16 Constraints 1. Class Hierarchy 5. Field Access 2. Class Instantiation 6. Array Access 3. Local Variables 7. Static Initialization 4. Method Calls 8. Exception Handling 16

17 Constraints 1. Class Hierarchy 5. Field Access 2. Class Instantiation 6. Array Access 3. Local Variables 7. Static Initialization 4. Method Calls 8. Exception Handling 17

18 Library Points-to Set (LPT) Application Library pt(v1) = o 1 o3 pt(v3) = o 1 o4 LPT = o2 o1 o5 o3 pt(v2) = o 2 o3 [Tip & Palsberg OOPSLA 00] 18

19 Library Callbacks class A extends L { m(); Application calls Library class L { m(); 1 class B extends L { m(); class C { m(); LPT = A C 2 19

20 [K. Ali and O. Lhoták, ECOOP 13] 20

21 JAR SCA JAR Placeholder Library 21

22 SCA Application Placeholder Library REF averroes.library REF REF 22

23 averroes.library 23

24 public class averroes.library { public static Object librarypointsto; public static void doitall() { // Class instantiation // Library callbacks // Field writes // Array element writes // Exception Handling 24

25 Evaluated for SOOT and DOOP 300x smaller library! Up to 15x faster analysis Up to 8x less memory Precise Sound 25

26 Implementation Tweaks 26

27 Class Loaders in WALA ClassLoaderReference.Primordial ClassLoaderReference.Extension ClassLoaderReference.Application 27

28 Problem 1: App.methods() public class Library { ClassLoaderReference.Primordial ClassLoaderReference.Extension ClassLoaderReference.Application public static void doitall() { // Class instantiation A a = new A(); // Library callbacks a.foo(); 28

29 Problem 1: App.methods() public class Library { ClassLoaderReference.Primordial ClassLoaderReference.Extension ClassLoaderReference.Application public static void doitall() { // Class instantiation A a = new A(); // Library callbacks a.foo(); 29

30 Solution 1: App.methods() public class Library { ClassLoaderReference.Primordial ClassLoaderReference.Extension ClassLoaderReference.Application public static void doitall() { // Class instantiation A a = new A(); // Library callbacks a.foo(); 30

31 Problem 2: doitall() public class Library { ClassLoaderReference.Primordial public static void doitall() {... ClassLoaderReference.Extension public class PrintStream { ClassLoaderReference.Application public void println(string s) {... Library.doItAll();... 31

32 Solution 32

33 public class AbstractLibrary { public static AbstractLibrary instance; public abstract void doitall(); ClassLoaderReference.Primordial public class Library extends AbstractLibrary { static { AbstractLibrary.instance = new Library(); public void doitall() {... A a = new A(); ClassLoaderReference.Application public class PrintStream { public void println(string s) {... AbstractLibrary.instance.doItAll();... ClassLoaderReference.Primordial 33

34 public class AbstractLibrary { public static AbstractLibrary instance; public abstract void doitall(); ClassLoaderReference.Primordial public class Library extends AbstractLibrary { static { AbstractLibrary.instance = new Library(); public void doitall() {... A a = new A(); ClassLoaderReference.Application public class PrintStream { public void println(string s) {... AbstractLibrary.instance.doItAll();... ClassLoaderReference.Primordial 34

35 public class AbstractLibrary { public static AbstractLibrary instance; public abstract void doitall(); ClassLoaderReference.Primordial public class Library extends AbstractLibrary { static { AbstractLibrary.instance = new Library(); public void doitall() {... A a = new A(); ClassLoaderReference.Application public class PrintStream { public void println(string s) {... AbstractLibrary.instance.doItAll();... ClassLoaderReference.Primordial 35

36 Evaluation 36

37 Evaluation What are the performance gains of using the placeholder library? How precise is Averroes? Does using the placeholder library affect the soundness of WALA? 37

38 Library Size SCA ON AVG 300x SMALLER Original Library ~ 25 MB Placeholder Library ~ 80 KB 38

39 Execution Time ON AVG 2x FASTER Execution Time (s) antlr bloat chart hsqldb luindex lusearch pmd xalan compress db jack javac jess raytrace WALA Analysis WALA Overhead WALAAVE Analysis WALAAVE Overhead AVERROES 39

40 Memory Usage Memory Usage (GB) ON AVG 2x LESS antlr bloat chart hsqldb luindex lusearch pmd xalan compress db jack javac jess raytrace WALA WALAAVE 40

41 Precision of Averroes 41

42 Precision of Averroes WALAAVE \ WALA WALA ANTLR 2.06% BLOAT 19.66% CHART 22.76% HSQLDB 32.56% LUINDEX 4.35% LUSEARCH ON AVG 10.45% 8% PMD 7.78% XALAN 33,100.00% COMPRESS 0.00% DB 7.04% JACK 3.63% JAVAC 1.21% JESS 8.70% RAYTRACE 0.00% 42

43 Imprecise Library Callbacks WALAAVE \ WALA HSQLDB org.hsqldb.jdbc.* 577 (70%) Application Library Client Code JDBC Interface JDBC Implementation 43

44 Sound(i?)ness 44

45 Unsoundness w.r.t. Dynamic Call Graphs DYNAMIC \ WALA DYNAMIC DYNAMIC \ WALAAVE DYNAMIC ANTLR - - BLOAT - - CHART 6% 6% HSQLDB 4% 4% LUINDEX 1% - LUSEARCH 1% - PMD 3% - XALAN 99% - COMPRESS - - DB - - JACK - - JAVAC - - JESS - - RAYTRACE

46 Reasons for Unsoundness public void notifylisteners(event event) { Object[] ls = this.listenerlist.getlistenerlist(); for (int i = ls.length - 2; i >= 0; i -= 2) { if (ls[i] == Listener.class) { ((Listener)ls[(i + 1)]).changed(event); 46

47 Correctness Proof Based on Featherweight Java 47

48 FJ m m 48

49 FJ FJ AVE m m m m 49

50 Evaluation Summary 300x smaller library! 2x faster 2x less memory Precise Sound 50

51 What s Next? 51

52 What s Next? Application Library Analyzing Large Frameworks SCA DOOP Incremental JAR Generation Better Reflection Support SCA SCALACG Automatic Library Detection Integration with WALA The Past The Future 52

53 Analyzing Large Frameworks library is much larger than application event-based systems => many callbacks modeling application lifecycle is not trivial The Future 53

54 Better Reflection Support better support for reflection automatic library detection incremental JAR generation The Future 54

55 Integration with WALA WALA Analysis Scope WALA Averroes Analysis Scope The Future 55

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63 Technische Universität Darmstadt karimali.ca