1 / 19

Java Pathfinder

Java Pathfinder. Rafael Duarte rmd@cin.ufpe.br. Agenda. Motivation Model-Checking Java Pathfinder Why Java Pathfinder? Conclusion. Motivation. Assuring the correctness of concurrent Java programs is a difficult task Java primitives for concurrency are very error prone

Download Presentation

Java Pathfinder

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. Java Pathfinder Rafael Duarte rmd@cin.ufpe.br

  2. Agenda • Motivation • Model-Checking • Java Pathfinder • Why Java Pathfinder? • Conclusion

  3. Motivation • Assuring the correctness of concurrent Java programs is a difficult task • Java primitives for concurrency are very error prone • synchronized, wait(), notify() can easily introduce deadlocks • Model Checking can be a powerful tool to help addressing these issues

  4. Model Checking Algorithms, rather than proof calculi, for system verification which operate on a system model (semantics), rather than a system description (syntax). (Tom Henzinger)

  5. Model Checking From CSP, Promela, Java Graph traversing algorithm Answer Yes if model satisfies specification Counter-example if model does not satisfy specification Model CheckingTool System Model Specification (System Properties) Temporal logic formulas, refinement

  6. Model Checking • Drawbacks • State explosion • scalability

  7. Java Pathfinder Java PathFinder (JPF) is a system to verify executable Java bytecode programs. In its basic form, it is a Java Virtual Machine (JVM) that is used as an explicit statesoftware model checker, systematically exploring all potential execution paths of a program to find violations of properties like deadlocks or unhandled exceptions(JPF site)

  8. Java Pathfinder

  9. Model Extraction • Reducing the state explosion • Symmetry reductions • Abstract interpretation • Static analysis • Runtime analysis

  10. What can be checked with JPF • Out of the box • Deadlock and unhandled exceptions • Race conditions and heap bounds • Almost every java applications • Closed systems • No support for java.awt and java.net • Limited support for java.io and reflection • No support for libraries with native code • Application size ~10Kloc

  11. Java Pathfinder Extensibility • Users can implement their own properties to be checked • Search/VMListener • Provide an Listener to specific JPF events

  12. Running JPF • Download it from the svn repository (strongly recommended) • Run the JPF class passing the class to be checked as parameter • Lots of possible parameters • Lacks an usable interface (GUI)

  13. Our work…

  14. Parallelizing Java • Automatic transformations to convert a sequential Java program into a concurrent one. • Issues concerning the transformation’s correctness • It should not introduce errors in the original program • Take advantage of multiprocessors

  15. Parallelizing Java Sequential Concurrent com1; com2; com3; com4; com5; Splitting com1; com2; com5; com3; com4;

  16. Why Java Pathfinder? • We believe in the possibility of extending it to check data sharing • Semantic verification would allow us to deal with reference aliasing • Independent commands would be put in parallel • Data flow analysis would tell us which commands are independent (work in different data partitions)

  17. Dataflow Analysis Conta c = new Conta(“1234-5”); Conta d = c; int i = Math.random() * 10; d.setSaldo(100.0); c.creditar(50.0); int j = i + 50;

  18. Final Remarks • Java Pathfinder is a powerful tool to verify java programs • But its use requires some expertise • Very useful when working with concurrency • Its extensibility mechanism greatly increases the way it can be exploited

  19. References • Java Pathfinder site • http://javapathfinder.sourceforge.net/ • Model Checking Programs (JPF paper) • Four Lectures on Model Checking

More Related