The Fermi Paradox

“There’s also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say it’s as high as 50%, but let’s go with the more conservative 22% that came out of a recent PNAS study. That suggests that there’s a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets.

So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach…”

The Fermi Paradox

Principles of Distributed Computing (lecture collection)

“Distributed computing is essential in modern computing and communications systems. Examples are on the one hand large-scale networks such as the Internet, and on the other hand multiprocessors such as your new multi-core laptop. The lecture notes on this webpage introduce the principles of distributed computing, emphasizing the fundamental issues underlying the design of distributed systems and networks: communication, coordination, fault-tolerance, locality, parallelism, self-organization, symmetry breaking, synchronization, uncertainty. We explore essential algorithmic ideas and lower bound techniques, basically the “pearls” of distributed computing. Each chapter covers a fresh topic.

Note that the order of the chapters is more or less arbitrary. Each chapter is mostly independent, with the occasional reference to another chapter…”

Graceful server restart with Go

“Go has been designed as a backend language and is mostly used as such. Servers are the most common type of software produced with it. The question I’m going to answer here is: how to cleanly upgrade a running server?



  • Do not close any of the existing connections: for instance, we don’t want to cut down any running deployment. However we want to be able to upgrade our services whenever we want without any constraint.
  • The socket should always be available for the users: if the socket is unavailable at any moment some user may get a ‘connection refused’ message which is not acceptable.
  • The new version of the process should be started and should replace the old one…”

mlpack: a scalable C++ machine learning library

"mlpack is an intuitive, fast, scalable C++ machine learning library, meant to be
a machine learning analog to LAPACK. It aims to implement a wide array of
machine learning methods and function as a "swiss army knife" for machine
learning researchers.

The mlpack website can be found at and contains numerous
tutorials and extensive documentation.  This README serves as a guide for what
mlpack is, how to install it, how to run it, and where to find more
documentation.  The website should be consulted for further information..."

VRAM based file system for Linux

“Unused RAM is wasted RAM, so why not put some of that VRAM in your graphics card to work?

vramfs is a utility that uses the FUSE library to create a file system in VRAM. The idea is pretty much the same as a ramdisk, except that it uses the video RAM of a discrete graphics card to store files. It is not intented for serious use, but it does actually work fairly well, especially since consumer GPUs with 4GB or more VRAM are now available.

On the developer’s system, the continuous read performance is ~2.4 GB/s and write performance 2.0 GB/s, which is about 1/3 of what is achievable with a ramdisk. That is already decent enough for a device not designed for large data transfers to the host, but future development should aim to get closer to the PCI-e bandwidth limits. See the benchmarks section for more info…”