My Load Test

Recently a client asked me “What’s the difference between LoadRunner and Performance Center? They’re both sold by the same company, but they seem to do much the same thing.”

I think he could see that I was about to launch into a half-hour lecture on the topic because he quickly added “Just give me the elevator pitch”.

I thought for a second and explained “Well, obviously they are both used for performance testing, but Performance Center is the Enterprise version of LoadRunner; so it suits larger companies who need to run performance testing for multiple projects at the same time without the problem of sharing a Controller or purchasing duplicate licenses.”

He put his hand on my shoulder and said “That’s an okay pitch, but it has one big problem. Let’s go and get a coffee, and I’ll tell you what I think of when I hear someone say ‘enterprise software’.”
Read the rest of this entry »

Imagine that you need to load test a Network Management System (NMS), which might receive hundreds of SNMP traps every second from tens of thousands of devices on the network. Clearly it is impractical to actually deploy thousands of devices in a test environment, so you need a tool to generate the SNMP traps at the required volume.

A quick search for SNMP load testing tools shows that they are all fairly primitive, with poor support for creating SNMP traps with dynamic field values, and no support for integrated system monitoring. There are definitely no tools with the same level of functionality as LoadRunner.

Unfortunately LoadRunner does not have an SNMP vuser type…but fortunately LoadRunner is endlessly extensible, if you are not afraid to get your hands dirty. Read on for how I created a LoadRunner script to send SNMP traps to an NMS…
Read the rest of this entry »

If you need to run a Unix command on a remote server with a LoadRunner script (running on Windows), then there is a neat program called plink that you will find very useful.

If you use any variety of Unix, you will probably already by using PuTTY; well plink is is distributed with PuTTY, and allows you to run remote Unix commands from your DOS prompt.

In this example, I have used it to collect disk I/O metrics from a remote Solaris server.
Read the rest of this entry »

Everyone should already know that you can run a command-line program from a LoadRunner script using the system() function. If you have used this, you would already know that things become a little awkward when need to capture the output of the program.

The common solution is to pipe the output of the command to a file (i.e. system(“my_command > output_file.txt”)), and then read the contents of the file. This is clunky and awkward, and not safe when multiple virtual users are writing to the same file.

A much better solution is to run all your command-line (DOS) programs using the popen() function. Read on for examples…
Read the rest of this entry »

On increasingly rare occasions, you might be required to load test an application that has a Java-based client. While it’s nice for users to have an application that has a rich GUI, it will probably lead to a world of pain for you as a performance tester.

Don’t immediately reach for LoadRunner’s Java Record-Replay virtual user type. It might not be the right solution.

This article will guide you through your first steps when selecting the correct vuser type to test an application with a Java-based client…
Read the rest of this entry »

I like posting LoadRunner code snippets on My Load Test and, judging by the emails and comments that I get, a lot of people find them really useful. To make my code more readable, I have added syntax highlighting that uses the same colours you see in VuGen. If you would like to download a copy of the syntax highlighting code to use on your own blog or forum, or you would like to learn more about how I did it, read on…
Read the rest of this entry »