Infohit blog

Improving the speed of Semantic Mediawiki

admin — Wed, 11 Aug 2010 13:53:52 MST

Improving the speed of Semantic Mediawiki page load times by enforcing caching with expires header.

I run Semantic Mediawiki on my local portable. The machine is getting on a bit, about 4 years old, but still runs Semantic Mediawiki (with the Halo extension) quite well. For some time I have been running memcache and eaccelerator with xampp under windows to produce a good result, however I recently made another discovery which radically speeds up page load times. Using Yahoo YSlow I found that a large number of elements are used to make up a semantic mediawiki page, about 75 elements (including 29 Javascripts and 20 css) for a normal page, and it goes up to about 150 when editing a page with the richmedia editor (including 86 javascripts, and 27 css) . This means there are a large number of requests made to the server each time a page is loaded. This was in fact the slower part of the page load. Using the mod_expires and mod_headers handler of apache, I was able to make significant improvements in load times by effectively forcing the caching of static elements locally on the browser.

To do this I added the following to my httpd.conf configuration files.

1) Ensure the following lines are not commented:

LoadModule expires_module modules/mod_expires.so
LoadModule headers_module modules/mod_headers.so

2) Add the following lines just above the <Directory> directive

ExpiresActive On
ExpiresDefault "access plus 300 seconds"

3) Add the following lines just before the end of the </Directory> directive

ExpiresByType text/html "access plus 1 day"
ExpiresByType text/css "access plus 1 day"
ExpiresByType text/javascript "access plus 1 day"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType application/x-shockwave-flash "access plus 1 day"

Until now there seems to be no ill effects, although your mileage may vary.

Eclipse Profiling Tools Eclipse TPTP fails with Ubuntu Lucid

admin — Thu, 13 May 2010 05:45:32 MST

Eclipse Profiling Tools Eclipse TPTP do not work with Ubuntu Lucid Lynx (Ubuntu 10.04) as supplied.

After installing the Eclipse TPTP plugin, when selecting an appropriate Unit Test class and using 'Profile As--->JUnit Test' A dialog box is show with the following error in the 'Monitor' tab:

IWAT0435E An Error occurred when connecting to the host.

The cause for this is that lib32stdc++5 is missing from the Ubuntu Lucid and Karmic Distributions, and the pre-compiled code in the Eclipse TPTP plugin requires this to be on the system. The missing library can be installed as follows:

mkdir /tmp/libstdc++5
cd /tmp/libstdc++5
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-3.3/libstdc++5_3.3.6-17ubuntu1_amd64.deb
sudo dpkg -i libstdc++5_3.3.6-17ubuntu1_amd64.deb

Infohit Shorts

admin — Thu, 06 May 2010 12:57:18 MST

Just launched a new section called 'Infohit Shorts'. Here I will post useful tips that are too short to make a full post. If you would like to comment on anything in Infohit Shorts, please leave a comment on this blog post.

Resize Root Partition on boot from root on EBS EC2 instance

admin — Wed, 09 Dec 2009 16:18:57 MST

How to resize the root partition on an Amazon EC2 instance which has its root partition backed by Elastic Block Storage (EBS).

At the time of writing the documentation seems a little incomplete in this respect, so here is what I did to make a larger root partition on an Ubuntu Karmic Server EC2 instance.

Stop the machine (do not terminate it)
Take a snapshot
When the snapshot has completed, restart the machine
Create a new volume in the same availability zone as the current one, but with the new size
Attach the new volume to the old machine using the amazon aws console (the device I used is /dev/sdd)
e2fsck -f /dev/sdd
resize2fs -f /dev/sdd
e2fsck -f /dev/sdd
Detach the volume
Create a new shapshot
Create a new AMI from the new snapshot

      ./ec2-register -K ~/ec2/pk-mypk.pem -C ~/ec2/cert-mycert.pem -n MyUniqueName -s snap-mysnap --kernel aki-5f15f636 --ramdisk ari-0915f660

Installing Thunderbird 3.0 on Ubuntu Karmic

admin — Wed, 09 Dec 2009 14:01:52 MST

Fabien Tassin maintains a PPA repository of recently released and pre-release Mozilla software at: https://launchpad.net/~ubuntu-mozilla-daily/+archive/ppa

With Ubuntu Karmic its fairly easy to add this repository to the list of sources aptitude will use.

Open a command line terminal and use the following:

  sudo add-apt-repository ppa:ubuntu-mozilla-daily
  sudo apt-get update

You can then install Thunderbird 3 using Synaptic Package Manager or from the command line:

  apt-get install thunderbird-3.0

If you are going to migrate from Thunderbird 2 to 3 do not start Thunderbird yet!

In order to smoothly migrate your profile from Thunderbird 2, you should do the following:

Uninstall Thunderbird 2.0 using Synaptic or Aptitude
Backup the directory ~/.mozilla-thunderbird
Make a symbolic link from .thunderbird-3.0 to .mozilla-thunderbird using

     cd ~/
     ln -fs .mozilla-thunderbird .thunderbird-3.0

Then start Thunderbird 3.0 (You will actually find that its under a menu item called Shredder 3 Mail/News). I am not sure why but I suspect its to do with licensing restrictions on distributing binaries

Have fun. And remember - make a backup before you start