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February 01, 2011

Mark Wielaard: New GPG key. Finally created a new GPG key using gnupg. The old one was a DSA/1024 bits one and 8 years old. The new one is a RSA/2048 bits one. I will use the new one in the future to sign any release tarballs I might create. pub 2048R/57816A6A 2011-01-29 Key f...

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February 01, 2011

Andrew Hughes: [SECURITY] IcedTea6 1.7.8, 1.8.5, 1.9.5 Released!. We are pleased to announce a new set of security releases, IcedTea6 1.7.8, IcedTea6 1.8.5 and IcedTea6 1.9.5. This update contains the following security updates: The IcedTea project provides a harness to build the source code from OpenJDK6 u...

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Thinking about How Much Fun It Is to Develop Multi-Threaded Apps

We've just published a new article by Dibyendu Roy, Rethinking Multi-Threaded Design Principles, Part 2. In this article, Dibyendu presents and overview of the laws and principles that relate to application speed-up due to multithreading, then he talks about locks and non-blocking operations and their impact. If you've worked with multithreaded development, your probably familiar with Amdahl's law, which defines the theoretical speed-up of an application when part of its code is parallelized. In Dibyendu's article, he presents the speed-up using this equivalent representation: Speed Enhancement = 1 / (Fs + ((1 - Fs) / N)) Here, Fs is the fraction of the program that is running sequentially, and N is the number of cores or processors. Here's Dibyendu's explanation: if N is 1, we get no speedup, but as N increases (tends to infinity, (1 - Fs)/N becomes 0), the speed is totally dependent on the 1/Fs part - which leads to the conclusion that, to improve execution speed of an application, we need to figure out ways or patterns to make more code execute in parallel. This really is a very interesting equation, and it illustrates why sometimes beginning developers are stunned to find out that a performance improvement they spent days or weeks working on ultimately has little impact on the application's actual performance. The question is: how do you "compute" Fs, the fraction of the program that is...

Date: April, 14 2010

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