In an earlier post I mentioned that one goal of the new introductory curriculum at Carnegie Mellon is to teach parallelism as the general case of computing, rather than an esoteric, specialized subject for advanced students. Many people are incredulous when I tell them this, because it immediately conjures in their mind the myriad complexities…
I recently diagnosed the root cause of a concurrency bug, CR6822370,
and thought it sufficiently interesting to share the details. (CR 6822370 actually represents a
cluster of bugs that are now thought to be related by a common underlying issue).
Briefly, we have a lost wakeup bug in the native C++ Parker::park() platform-specific
infrastructure code that implements java.util.concurrent.LockSupport.park().
The lost wakeup arises from a race that itself arises because of architectural
reordering that in turn occurs because of missing memory barrier instructions.
The lost wakeup may manifest as various 'hangs' or instances of progress failure.
Program performance is always a concern, even in this era of high-performance hardware. This article, the first in a two-part series, guides you around the many pitfalls associated with benchmarking Java code. Part 2 covers the statistics of benchmarking and offers a framework for performing Java benchmarking. Because almost all new languages are virtual machine-based, the general principles the article describes have broad significance for the programming community at large.
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E. D'Osualdo, J. Kochems, and L. Ong. Proceedings of the 2nd Edition on Programming Systems, Languages and Applications Based on Actors, Agents, and Decentralized Control Abstractions, page 137--140. ACM, (2012)
S. Tasharofi, R. Karmani, S. Lauterburg, A. Legay, D. Marinov, and G. Agha. Formal Techniques for Distributed Systems: Joint 14th IFIP WG 6.1 International Conference, FMOODS 2012 and 32nd IFIP WG 6.1 International Conference, FORTE 2012, Stockholm, Sweden, June 13-16, 2012. Proceedings, page 219--234. Springer, (2012)