JThreadSpy: teaching multithreading programming by analyzing execution traces

ABSTRACT

Multithreading introduces a degree of complexity that is often difficult to grasp by beginners both because of many false assumptions made about the scheduling process and because it is not possible to adopt a trial and error strategy aimed at figuring out what exactly happens during the execution, as a consequence of the intrinsic non determinism of threaded execution.

This article describes JThreadSpy, a tool for dynamic instrumentation of Java programs, aimed at registering execution traces of each thread and displaying them with a selectable level of detail.

JThreadSpy relies on the ASM framework to dynamically instrument methods during class loading, in order to insert suitable method calls that produce an execution trace that is later used to display an annotated UML sequence diagram, highlighting different threads and synchronization constructs.

JThreadSpy proved to be a valuable tool for students engaged in an object-oriented programming course at Politecnico di Torino. By graphically analysing execution flows, students could understand, in an easier way, the non-determinism introduced by the scheduler, the effects of synchronization constructs, the impact of multicore processor architectures, as well as identify critical sections, deadlocks and other anomalies of concurrent programs.

REFERENCES

• 1: ASM Home page: http://asm.objectweb.org.
• 2: BCEL Byte Code Engineering Library: http://jakarta.apache.org/bcel/manual.html.
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INDEX TERMS

Primary Classification:
  D. Software
  D.1 PROGRAMMING TECHNIQUES
      D.1.3 Concurrent Programming
          Subjects: Parallel programming

Additional Classification:
  D. Software
  D.1 PROGRAMMING TECHNIQUES
      D.1.5 Object-oriented Programming
  D.2 SOFTWARE ENGINEERING
      D.2.5 Testing and Debugging
          Subjects: Tracing; Testing tools (e.g., data generators, coverage testing); Monitors
  D.3 PROGRAMMING LANGUAGES
      D.3.2 Language Classifications
  D.4 OPERATING SYSTEMS
      D.4.1 Process Management
          Subjects: Concurrency; Deadlocks; Scheduling; Synchronization; Threads

  K. Computing Milieux
  K.3 COMPUTERS AND EDUCATION
      K.3.2 Computer and Information Science Education
          Subjects: Computer science education

General Terms:
Experimentation, Languages, Measurement, Reliability, Verification

Keywords:
concurrent programming, education, execution trace analysis, object-oriented, runtime code instrumentation, software visualization