Formalising Java's Data Race Free Guarantee

13 years 10 months ago

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We formalise the data race free (DRF) guarantee provided by Java, as captured by the semi-formal Java Memory Model (JMM) [1] and published in the Java Language Speciﬁcation [2]. The DRF guarantee says that all programs which are correctly synchronised (i.e., free of data races) can only have sequentially consistent behaviours. Such programs can be understood intuitively by programmers. Formalisation has achieved three aims. First, we made deﬁnitions and proofs precise, leading to a better understanding; our analysis found several hidden inconsistencies and missing details. Second, the formalisation lets us explore variations and investigate their impact in the proof with the aim of simplifying the model; we found that not all of the anticipated conditions in the JMM deﬁnition were actually necessary for the DRF guarantee. This allows us to suggest a quick ﬁx to a recently discovered serious bug [3] without invalidating the DRF guarantee. Finally, the formal deﬁnition provides...

David Aspinall, Jaroslav Sevcík

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