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Averroes: Letting go of the library!
Karim Ali
Workshop on WALA - PLDI ‘15 June 13th, 2015
Karim Ali Averroes: Letting go of the library! 2
public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!");}
}
Karim Ali Averroes: Letting go of the library!
• ~ 8 seconds
• ~ 600 MB of memory
• > 900 reachable methods
• > 1,700 call edges3
public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!");}
}
Karim Ali Averroes: Letting go of the library!
Hello, World!
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Karim Ali Averroes: Letting go of the library!
Partial-Program Analysis
5
Karim Ali Averroes: Letting go of the library!
Partial-Program Analysis
6
I'd like to ignore library code
what about callbacks?
this would be unsound but better than nothing
ignore non-application program elements (e.g., system libraries)?
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
Karim Ali Averroes: Letting go of the library!
Partial-Program Analysis
7
?
Karim Ali Averroes: Letting go of the library! 8
Ideal Call Graph
Karim Ali Averroes: Letting go of the library! 9
Ideal Call Graph
Whole-Program Call Graph
Karim Ali Averroes: Letting go of the library! 10
Ideal Call Graph
Whole-Program Call Graph
Incomplete Call Graph (unsound)
Karim Ali Averroes: Letting go of the library! 11
Ideal Call Graph
Whole-Program Call Graph
Incomplete Call Graph (unsound)
Conservative Call Graph
(highly imprecise)
Karim Ali Averroes: Letting go of the library! 12
Analyzed Code
?m(){ ...
}
c.center = new Point(0,0);
call method
create objectmodify field
Conservative Assumptions
Karim Ali Averroes: Letting go of the library!
Ideal Call Graph
Whole-Program Call Graph
Incomplete Call Graph (unsound)
Conservative Call Graph
(highly imprecise)
Partial-Program Call Graph
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Karim Ali Averroes: Letting go of the library!
The Separate Compilation Assumption
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Karim Ali Averroes: Letting go of the library!
The Separate Compilation Assumption
All of the library classes can be compiled in the absence of the application classes.
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Karim Ali Averroes: Letting go of the library!
Constraints
1. Class Hierarchy
2. Class Instantiation
3. Local Variables
4. Method Calls
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5. Field Access
6. Array Access
7. Static Initialization
8. Exception Handling
Karim Ali Averroes: Letting go of the library!
Constraints
1. Class Hierarchy
2. Class Instantiation
3. Local Variables
4. Method Calls
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5. Field Access
6. Array Access
7. Static Initialization
8. Exception Handling
Karim Ali Averroes: Letting go of the library!
Library Points-to Set (LPT)
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Application Library
pt(v1) = o1 o3
pt(v2) = o2 o3
pt(v3) = o1 o4
LPT =o1
o2 o3 o5
[Tip & Palsberg OOPSLA’00]
Karim Ali Averroes: Letting go of the library!
Library Callbacks
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Application Library
class C { m(); }
class B extends L { m(); }
class A extends L { m(); } calls
class L { m(); }
1
LPT = A C
2
Karim Ali Averroes: Letting go of the library! 20
[K. Ali and O. Lhoták, ECOOP ’13]
Karim Ali Averroes: Letting go of the library!
JAR
Placeholder Library
SCA
JAR
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Karim Ali Averroes: Letting go of the library! 22
REF
REF
Placeholder Library
SCA
REF
averroes.Library
Application
Karim Ali Averroes: Letting go of the library! 23
averroes.Library
Karim Ali Averroes: Letting go of the library! 24
public class averroes.Library {
public static Object libraryPointsTo;public static void doItAll() {// Class instantiation
// Library callbacks
// Field writes
// Array element writes
// Exception Handling}
}
Karim Ali Averroes: Letting go of the library!
Evaluated for SOOT and DOOP
✓ 300x smaller library!
✓ Up to 15x faster analysis
✓ Up to 8x less memory
✓ Precise
✓ Sound
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Karim Ali Averroes: Letting go of the library!
Implementation Tweaks
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Karim Ali Averroes: Letting go of the library!
Class Loaders in WALA
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ClassLoaderReference.Extension
ClassLoaderReference.Primordial
ClassLoaderReference.Application
Karim Ali Averroes: Letting go of the library!
Problem 1: App.methods()
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ClassLoaderReference.Extension
ClassLoaderReference.Primordial
ClassLoaderReference.Application
public class Library {
public static void doItAll() {// Class instantiationA a = new A();
// Library callbacksa.foo();
}}
Karim Ali Averroes: Letting go of the library!
Problem 1: App.methods()
29
ClassLoaderReference.Extension
ClassLoaderReference.Primordial
ClassLoaderReference.Application
public class Library {
public static void doItAll() {// Class instantiationA a = new A();
// Library callbacksa.foo();
}}
Karim Ali Averroes: Letting go of the library!
Solution 1: App.methods()
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ClassLoaderReference.Extension
ClassLoaderReference.Primordial
ClassLoaderReference.Application
public class Library {
public static void doItAll() {// Class instantiationA a = new A();
// Library callbacksa.foo();
}}
Karim Ali Averroes: Letting go of the library!
Problem 2: doItAll()
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ClassLoaderReference.Extension
ClassLoaderReference.Primordial
ClassLoaderReference.Application
public class Library {
public static void doItAll() {...
}}
public class PrintStream {
public void println(String s) {...
Library.doItAll();...
}}
Karim Ali Averroes: Letting go of the library!
Solution
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Karim Ali Averroes: Letting go of the library! 33
public class AbstractLibrary {public static AbstractLibrary instance;public abstract void doItAll();
}
public class Library extends AbstractLibrary {static {
AbstractLibrary.instance = new Library();}
public void doItAll() {...A a = new A();
}}
public class PrintStream {public void println(String s) {
... AbstractLibrary.instance.doItAll();
...}
}
ClassLoaderReference.Primordial
ClassLoaderReference.Primordial
ClassLoaderReference.Application
Karim Ali Averroes: Letting go of the library! 34
public class AbstractLibrary {public static AbstractLibrary instance;public abstract void doItAll();
}
public class Library extends AbstractLibrary {static {
AbstractLibrary.instance = new Library();}
public void doItAll() {...A a = new A();
}}
public class PrintStream {public void println(String s) {
... AbstractLibrary.instance.doItAll();
...}
}
ClassLoaderReference.Primordial
ClassLoaderReference.Primordial
ClassLoaderReference.Application
Karim Ali Averroes: Letting go of the library!
public class AbstractLibrary {public static AbstractLibrary instance;public abstract void doItAll();
}
public class Library extends AbstractLibrary {static {
AbstractLibrary.instance = new Library();}
public void doItAll() {...A a = new A();
}}
public class PrintStream {public void println(String s) {
... AbstractLibrary.instance.doItAll();
...}
}
ClassLoaderReference.Primordial
ClassLoaderReference.Primordial
ClassLoaderReference.Application
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Karim Ali Averroes: Letting go of the library!
Evaluation
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Karim Ali Averroes: Letting go of the library!
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?
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Karim Ali Averroes: Letting go of the library!
Library Size
38
SCA
Original Library ~ 25 MB
Placeholder Library ~ 80 KB
300xSMALLER
ON AVG
Karim Ali Averroes: Letting go of the library! 39
Execution Time
WALAOverhead WALAAVEAnalysis WALAAVE
OverheadWALAAnalysis AVERROES
Exec
utio
n Ti
me
(s)
0
5
10
15
20
25
30
antlr bloat chart hsqldb luindex lusearch pmd xalan compress db jack javac jess raytrace
2xFASTER
ON AVG
Karim Ali Averroes: Letting go of the library! 40
WALA WALAAVE
Memory UsageM
emor
y Us
age
(GB)
0.00.10.20.30.40.50.60.70.80.91.01.1
antlr bloat chart hsqldb luindex lusearch pmd xalan compress db jack javac jess raytrace
2xLESS
ON AVG
Karim Ali Averroes: Letting go of the library!
Precision of Averroes
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Karim Ali Averroes: Letting go of the library!
|WALAAVE \ WALA| |WALA|
ANTLR 2.06%BLOAT 19.66%CHART 22.76%HSQLDB 32.56%LUINDEX 4.35%LUSEARCH 10.45%
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
Precision of Averroes
8%ON AVG
Karim Ali Averroes: Letting go of the library! 43
Imprecise Library Callbacks
Application Library
JDBC Implementation
JDBC Interface
Client Code
WALAAVE \ WALA
HSQLDB org.hsqldb.jdbc.* 577 (70%)
Karim Ali Averroes: Letting go of the library!
Sound(i?)ness
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Karim Ali Averroes: Letting go of the library! 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 - -
Karim Ali Averroes: Letting go of the library!
Reasons for Unsoundness
46
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); } } }
Karim Ali Averroes: Letting go of the library!
Correctness ProofBased on Featherweight Java
47
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FJ…
m
…
m’
Karim Ali Averroes: Letting go of the library! 49
FJ FJAVE…
m
…
m’
…
m
…
m’
Karim Ali Averroes: Letting go of the library!
Evaluation Summary
✓ 300x smaller library!
✓ 2x faster
✓ 2x less memory
✓ Precise
✓ Sound
50
Karim Ali Averroes: Letting go of the library!
What’s Next?
51
Karim Ali Averroes: Letting go of the library!
Automatic Library Detection
What’s Next?Analyzing Large Frameworks
SCALACGSCA
DOOPSCA
Application Library
The Past The Future
Incremental JAR Generation
Better Reflection Support
Integration with WALA
52
Karim Ali Averroes: Letting go of the library!
Analyzing Large Frameworks
SCALACG
DOOP
The Future
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• library is much larger than application • event-based systems => many callbacks • modeling application lifecycle is not trivial
Karim Ali Averroes: Letting go of the library!
Better Reflection Support
SCALACG
DOOP
The Future
54
better support for reflection
automatic library detection
incremental JAR generation
Karim Ali Averroes: Letting go of the library!
WALA Averroes Analysis Scope
WALA Analysis Scope
Integration with WALA
SCALACG
DOOP
The Future
55
Averroes: Letting go of the library! Karim Ali
Technische Universität Darmstadt karimali.ca
https://github.com/karimhamdanali/averroes
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