Sunday, May 30, 2010


I recently attended a talk on Hadoop by Robert Chansler. One interesting concept I picked up was the concept of "federation" or simply "playing nice with users".

In the context of Hadoop, this means achieving backward compatibility with legacy versions of the software. E.g. when users run "old code" in clusters with a newer Hadoop version, their code can run correctly without modifications.

Titbit about Hadoop: the next Hadoop milestone will focus on security.

Friday, May 21, 2010

Scientific Paradigms

Foreword: This post is a follow up from a previous post on the Forth Paradigm.

The Four Paradigms and some examples:

1st Paradigm: Experimental
Conducting simple experiments to confirm hypothesis (e.g. Ben Franklin and the Kite Experiment), Young double slit experiment, chemical reactions, etc

2nd Paradigm: Theoretical
Theories of the Natural Sciences, Theoretical Computer Science,

3rd Paradigm: Computational Science
Engineering based fields, Solving games, Four color theorem, computer simulations, etc

4th Paradigm: Data-Intensive Research
Data mining, the schematic web, machine learning, distributed systems, the LHC, etc

Question: what makes the 4th paradigm compelling: how does it stack against the previous paradigms (e.g. efficiency, feasibility, etc)

For download: The Fourth Paradigm: Data-Intensive Scientific Discovery (the book)

Thursday, May 20, 2010

Bell's Law of Computer Classes

Bell's Law of Computer Classes formulated by Gordon Bell in 1972 describes how computer classes form, evolve and may eventually die out. New classes create new applications resulting in new markets and new industries

Friday, May 14, 2010

@Override in Java


Indicates that a method declaration is intended to override a method declaration in a superclass. If a method is annotated with this annotation type but does not override a superclass method, compilers are required to generate an error message.

Tip of the day: The @Override annotation is a useful feature to ensure that you are overriding the correct method. Mostly used in places such as:

public int hashCode()

public boolean equals(Object obj)

Ubuntu Lucid Lynx

Just upgraded to Ubuntu Lucid Lynx... but not without a few cheap tricks along the upgrading process.

1. Upgrade Using the Alternate CD

I upgraded using the alternate CD, then did a partial upgrade via the Internet. To upgrade using an alternate CD, I downloaded the alternate CD, mount it:

$ sudo mount -o loop ~/path/to/alternate/cd/ubuntu-10.04-alternate-i386.iso /media/cdrom0

Then hit Alt-F2, and ran gksu "sh /cdrom0/cdromupgrade"

This is probably the fastest upgrading method.

2. Not enough disk space... oops!

Ironically, I did not have enough disk space on my ext4 partition to do the partial upgrade via the Internet. After some Googling, I found a really neat trick:

$ sudo su
$ cd /var/cache/apt
$ mv archives archives-orig
$ ln -s /media/AnotherPartition archives
$ mkdir archives/partial

Run the update manager, and complete the upgrade process. After installing:

$ rm archives
$ mv archives-orig archives

3. Getting Nvidia drivers to work again

I had some difficulty getting the Nvidia 195.36.24 driver to work again as the installation script failed. I followed the instructions on to solve the problem.

Specifically, in /etc/modprobe.d/blacklist.conf,
Adding the following lines helped:

blacklist vga16fb
blacklist nouveau
blacklist rivafb
blacklist nvidiafb
blacklist rivatv

4. Getting the window buttons back in the _right_ place

Although I had no problems adjusting to the left positioning of the minimize, maximize and close buttons, I found the change unappealing.

This guide clearly helped. One fact I wasn't aware of was that running "gconf-editor" was different from running "sudo gconf-editor" (the later meant a different thing).

5. Thunderbird 3

A fan of Thunderbird 2, I was disappointed at how Thunderbird 3 handled the IMAP messages. TD 3 attempted to download every single email message from the IMAP server (which quickly made me run out of disk space). Turning off synchronization did not help.

Fortunately, the following trick was useful:
In the config editor in TD 3 (Preferences->Advanced->General->Config Editor), set the following values to false


6. Sounds and ALSA

I found that my sound device was unable to work after upgrade (i.e. no sound). After realizing the alsaconf had been removed from the latest alsa package. I figured that a simple remove and reinstall would do the trick:

$ sudo apt-get remove alsa-base
$ sudo apt-get install alsa-base


Lucid Lynx comes with major under the hood improvements (faster boot up, better system integration, etc). Lucid Lynx is definitely worth the upgrade.