Compiler Construction

Volume 5501 of the series Lecture Notes in Computer Science pp 48-62

Compile-Time Analysis and Specialization of Clocks in Concurrent Programs

  • Nalini VasudevanAffiliated withDepartment of Computer Science, Columbia University
  • , Olivier TardieuAffiliated withIBM T.J. Watson Research Center
  • , Julian DolbyAffiliated withIBM T.J. Watson Research Center
  • , Stephen A. EdwardsAffiliated withDepartment of Computer Science, Columbia University


Clocks are a mechanism for providing synchronization barriers in concurrent programming languages. They are usually implemented using primitive communication mechanisms and thus spare the programmer from reasoning about low-level implementation details such as remote procedure calls and error conditions.

Clocks provide flexibility, but programs often use them in specific ways that do not require their full implementation. In this paper, we describe a tool that mitigates the overhead of general-purpose clocks by statically analyzing how programs use them and choosing optimized implementations when available.

We tackle the clock implementation in the standard library of the X10 programming language—a parallel, distributed object-oriented language. We report our findings for a small set of analyses and benchmarks. Our tool only adds a few seconds to analysis time, making it practical to use as part of a compilation chain.


Concurrency Static Analysis Synchronization Clocks X10 NuSMV