Monthly Archives: September 2009


reformating vmstat/sar/iostat logs :: loadrunner analysis

Quite often, I don’t get a read only ssh account to a server, so I can capture server metrics during runtime in loadrunner. This usually means I need to request the data to be sent to me after the test, which the sys admin will very easily do. The only problem here, is that a vmstat log is ugly, and difficult to read in raw text not to mention, had to analyse.
Test managers are generally very busy, and want a report with pretty pictures, giving them a view on what was happening during the run. Loadrunner analysis is a great tool for displaying such data, and has an import ability, for such problems, but first, we must convert our vmstat/sar/iostat file into a format that is easily graph-able.
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saving vugen paramaters into a file :: vugen

Performance and load testing has many input requirements. The most important and difficult to obtain, is clean and valid input data. I find that it’s often harder to request for data, than it is to just make my own. Unless the data needs to be aged, or processed somewhat, then you are stuck at the back of the queue. So think not of vugen/loadrunner as only a performance testing tool, but a gateway to process information on the application at a rapid rate. This is why I favour vugen/loadrunner as a data creation tool.
Once I set up my scripts they can often be reused throughout the lifespan of the project creating adhoc data when I need, quickly and rapidly.

Storing the data is something I’ve experimented with over the years, and have found that a mysql database is superior to store, validate, and call your from, all with a nice little wamp server, but more about that another time. If you want to just store your data in a CSV, text file, or any other format to your liking, you can do easily. I warn you, it’s clunky but it does work.
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loop/iterate through an ordinal array :: vugen

When saving paramaters through the web_reg_save_param, the ord=all option is very useful in finding multiple instances of your desired item.
Generally you can work out which ordinal you want to use, and call your parameter later using {paramaterValue_15} for the 16th ordinal (starts at 0). But what if you want to use every single ordinal found?.
Why? Well, why not! — you could have a situation where every ordinal found is a value which is the trail of a url, and you want to navigate to each subsequent url that this page returned. Since the ORD is an array, we should be able to call it easily via paramaterValue[#], right?. Wrong…this simply doesn’t work in vugen, however with a little bit of funky C coding, the answer is quite simple.
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script not compiling :: vugen

Vugen, is a good tool. But it does have some bugs.
Every so often, I find that I click the compile button, and it does not compile, instead it displays the output of the last script I ran.
What I’ve also found, is that sometimes when you run your script, it will have a previous version of the script in memory and run that version, presenting you with errors that do not really exist….quite annoying.
Even restarting Vugen will not fix the problem, however I have found a solution, but it’s not all that great.

When this issue occurs, hit ctrl+alt+del, and stop the mmdrv.exe process. Once that’s done, restart Vugen. You can try re-compiling (and it will compile) but for sometimes it will still replay your old version of the script.
If all else fails, take the Bill Gates way out, and reboot your machine.


epoch time :: vugen

Epoch time has been used for quite a while, it has many uses, but mainly, I have seen that developers use it for session Id’s. If you don’t know what epoch time is, you should question if you’re in the right profession, or just read this.

Correlation is always required, I spend many hours, sifting through code, working out where to correlate (I hate correlation studio btw).
To save time correlating session Id’s, I have found that its easier to just replace the value with the current epoch time, but how do you do this vugen?, especially when you need it down to milliseconds (Which most session Id’s are).
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