Archive for the ‘Programming’ Category

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HOW TO : Improve Jboss startup times

Thursday, December 31st, 2009

We run multiple applications in Jboss at my work and one of the applications used to take an inordinate time to come up. A typical application would take < 1 minute to get deployed and this particular application for some reason was taking ~7-8 minutes. We initially thought it was a bug in the code and gave hell to our development team :) .. But on closer investigation, we found out that a feature we enabled in the Jboss server settings which allows content to be hosted on network storage was causing the issue.

I blogged the feature in Jboss to follow sym links here (http://kudithipudi.org/2008/07/25/howto-configure-jboss-to-follow-symbolic-links/). So essentially when Jboss was started, it was checking all the content in these network path to check for applications to deploy. And traversing a network share with 1000s of directories isn’t fun :) ..

We fixed it by making a simple edit to the start up script. Here’s the psuedo code for the script

  1. Remove soft links to network share
  2. Start Jboss
  3. Put soft links to network share

And now the application starts in less than a minute :) .

I guess there might be other elegant ways to do this. i.e. Configure Jboss to only deploy certain applications, but this did the trick for us :) .

Posted in HOWTO, Linux, Programming, Technology, Web | No Comments »

HOW TO : Perl subfunction to unmount a partition in Linux

Friday, May 22nd, 2009

For my record…here’s a snippet of perl code that can be called as a sub function to unmount a partition in Linux.  The magic is in the line “grep m{$mountPoint}, qx{/bin/mount}”, which essentially lets you check if the partition is already mounted or not.

sub UnMountVolume($)
{
    my $mountPoint = $_[0];

    print "Unmounting $mountPoint\n";
	# Check if the mount point exists
	if ( grep m{$mountPoint}, qx{/bin/mount} )
	{
		#Let's try to unmount it
		system("/bin/umount $mountPoint");
	}
	else
	{
		print "$mountPoint is not mounted, so didn't have to do anything\n";
	}
}

As with any perl code, I am sure there are a tons of ways to do this in a more efficient and “cool” way.

Posted in Programming, Technology | No Comments »

HOW TO : Find which interface a particular IP address is configured on

Friday, May 22nd, 2009

There are a ton of scripts to find how many IP addresses  are configured on a system, but I could not find one, whic would show me which particular network interface an IP address was configured on. Here is a one liner, that will give you this information in Linux

/sbin/ifconfig | grep -B1 10.10.10.10 | awk '{if (NR==1) print $1}'

The same script can be changes a bit to support other operating systems too. Essentially, I am doing a grep (search) of the output of ifconfig, which shows all the network information on the system for a particular IP. At the same time, I am using the -B1 option, which will show the line above the matching line. Finally, I am piping this to awk and printing the first row in the first column.

Posted in HOWTO, Linux, Programming, Technology | 1 Comment »

HOW TO : Simple perl script to replace lines in file

Thursday, February 19th, 2009

Nothing fancy.. but here is a simple perl script to open a file, search for specific content in the a line and replace it with some other content.
open (SOURCE, "< source.xml")
or die "Could not open file source.xml: $!\n";

open (DESTINATION, ">modfile.xml")
or die "Could not open file modfile.xml: $!\n";

while (defined($line = <SOURCE>)) {
if ($line =~ m/YYYYYYYY/i) {
$line = "XXXXXXXXXXXXXXXXXXX\n";
}
print DESTINATION "$line";
}

close (SOURCE);
close (DESTINATION);

You are opening a file named source.xml, reading every line and if there is some text that matches “YYYYYYYY”, you are replacing the whole line with “XXXXXXXXXXXXXXXXXXX”. I am sure there are more elegant ways to write this :) .. but this will do the trick too..

Posted in HOWTO, Programming, Technology | 1 Comment »

SourceForge : Project of the Month

Saturday, January 24th, 2009

SourceForge.net is an online community supporting open source projects by providing hosting, distribution and subversion services. They choose a project every month from the hundreds of thousands of projects that are hosted on SourceForge based on popularity and activity. Most of the projects are the who is who of the Open source community. This is a good link to bookmark.. http://sourceforge.net/community/index.php/potm/

Posted in Programming, Technology | No Comments »

HOW TO : Configure JBoss to follow symbolic links

Friday, July 25th, 2008

Jboss, in addition to being an application server also serves static content. We recently ran into an issue where some static content was not displayed when users hit the link. The JBoss server kept spewing 404 errors, stating that the content was not found. On some hair pulling research, we figured out that JBoss, like Apache, does not follow/allow content mapped to a symbolic link.

So for example in your web app, you added a sym link to another directory, where most of your content is stored, Jboss would not show the content, when you go to the link.

Here’s a quick guide to fix this.

  1. Go to the deploy folder of the context you want to configure. For example, if you used the default context, you go to $JBOSS_HOME/server/default/deploy/jboss-web.deployer
  2. Edit the context.xml file and add allowLinking=”true” in the Context (NOTE : This allows Jboss to publish symbolic links on all apps in your application server, if you want to restrict it to just one particular app, you have to edit the context.xml in your specific application folder). Upon adding the option, our context.xml file looked as such


   

   
   org.jboss.web.tomcat.security.RunAsListener

More information on options for the context.xml can be found here

http://www.jboss.org/file-access/default/members/jbossweb/freezone/docs/2.1.0/config/context.html

For the record, Jboss configuration and accompanying documentation is what I call black magic :) .. Too many options, too many ways to do the same thing.

Posted in HOWTO, Linux, Programming, Technology, Web | 1 Comment »

Week 6 training and improved charts with Google Charts

Thursday, July 17th, 2008

Week 6 of the Chicago marathon training and I was again not able to keep up with my mid week runs. Although I did manage to improve the charts displaying the training program :) .. I added a new column to compare my actual milege to the recommended milege.

Here are the parameters I used

cht=bvg
chs=400×250
chtt=week+6+Training
chdl=Recommended+Miles|Actual+Miles
chco=ff0000,00ff00
chxt=x,y
chxr=1,0,15
chxl=0:|Mon|Tue|Wed|Thu|Fri|Sat|Sun|
chd=t:0,3,4,3,0,7,0|0,2,0,3,0,0,7
chbh=10

Posted in Programming, Running, Technology, Web | No Comments »

Tracking my runs using Google charts : Part II

Friday, July 11th, 2008

Comment from my friend Sri, after looking at my post regd using Google Charts API to track weekly runs.

” Hey V, You can show the value of the bars by using the variable CHM”..

Thx for making me lazy dude :) .. Here’s the upated image

Posted in HOWTO, Programming, Technology, Web | 1 Comment »

Tracking my runs using Google charts

Friday, July 11th, 2008

I wrote a brief blurb, when Google came out with their Google Charts API. The API essentially allows you to represent your data visually by just generating a URL.. I have been wanting to use this in real life for quite some time now and think I finally found a need :) . I am going to be tracking my weekly runs with using this API  moving forward.

Here’s a graphical representation of my runs for Week 5 of my traning for the Chicago marathon

Week 5

As you can see, I have been slacking off on my mid-week runs.

I used the following parameters to generate the graph

Type = cht (vertical bars)

Legend = chtt (Week 5 training)

Axis Values = chxl (Mon, Tue, Wed, Thur, Fri, Sat, Sun)

The URL I used to generate the image is http://chart.apis.google.com/chart?chtt=Week+5+Training&chts=FF0000,20&chdl=Miles&cht=bvs&chxt=x,y&chxl=0:|Mon|Tue|Wed|Thu|Fri|Sat|Sun|&chs=300×150&chd=t:0,0,3,0,0,0,10&chco=4d89f9,c6d9fd&chbh=20

I still need to figure out, how to show the values in the image and play with the ratio of the axis.

You can get all the information you need about this API by visiting this link http://code.google.com/apis/chart/

Posted in HOWTO, Programming, Running, Technology, Web | 3 Comments »

HOW TO : Select column in Notepad++

Tuesday, July 8th, 2008

Notepad++, is a great open source editor similar to EditPlus and UltraEdit. One of the features that I really appreciated in EditPlus, was the capability to select a column of data. I checked if NotePad++ has a similar feature and found the following hotkey that can be used to do this..

“Alt + Left Mouse Click” puts you in Column Mode Select

For a complete list of hotkeys that can be used with Notepad++, check out this link

http://notepad-plus.sourceforge.net/uk/shortcuts.php

Posted in HOWTO, Programming, Technology | 10 Comments »

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