Goldilocks: Efficiently Computing the Happens-Before Relation Using Locksets

  • Tayfun Elmas
  • Shaz Qadeer
  • Serdar Tasiran
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4262)


We present a new lockset-based algorithm, Goldilocks, for precisely computing the happens-before relation and thereby detecting data-races at runtime. Dynamic race detection algorithms in the literature are based on vector clocks or locksets. Vector-clock-based algorithms precisely compute the happens-before relation but have significantly more overhead. Previous lockset-based race detection algorithms, on the other hand, are imprecise. They check adherence to a particular synchronization discipline, i.e., a sufficient condition for race freedom and may generate false race warnings. Our algorithm, like vector clocks, is precise, yet it is efficient since it is purely lockset based.

We have implemented our algorithm inside the Kaffe Java Virtual Machine. Our implementation incorporates lazy evaluation of locksets and certain “short-circuit checks” which contribute significantly to its efficiency. Experimental results indicate that our algorithm’s overhead is much less than that of the vector-clock algorithm and is very close to our implementation of the Eraser lockset algorithm.


Concurrent Program Race Condition Java Virtual Machine Data Race Variable Access 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Tayfun Elmas
    • 1
  • Shaz Qadeer
    • 2
  • Serdar Tasiran
    • 1
  1. 1.Koç University 
  2. 2.Microsoft Research 

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