Memory considerations In Rational Performance tester (RPT)

Rational Performance tester tool is built on Java/Eclipse technology. Unlike Loadrunner, there are few memory implications that one has to be aware when using Rational performance tester.
RPT is GUI based tool and main GUI is enhanced eclipse. This is called workbench and mirrors controller in Loadrunner. The memory settings of the eclipse is key in having responsive workbench.
Other region of interest with regards to RPT memory is the driver memory . This memory is very key is executing higher number of users otherwise, you will face the issue of Java Out of memory very frequently. As evidently this two setting both relate to  JVM memory settings.



1. JVM memory settings for work bench
The settings for this JVM can be done in the eclipse.ini file found in two directories .  One in C:\Program Files\IBM\SDP and another one in C:\Program Files\IBM\SDP\rptse. The file in the former directory corresponds to IBM performance tester - full eclipse  and latter one for is plain version. Depending on what version you use you can make change to eclipse.ini file in respective version. To add memory to this JVM, add the startup parameter  -Xmx1200m into eclipse.ini file which mean maximum heap size for JVM is 1200 MB. And then restart the rational performance tester. After than you also view how much memory is been used by workbench by enabling the progress bar view for it in Window – > Preference: Show Heap Status

This JVM setting doesn't depend on number of users you run, but its useful when you open up many scripts, or open report from the test with large number of errors or with long duration.
2. JVM memory settings for driver in RPT agent controller
This is key memory setting and plays major role in the number of users that can be tested without Out of memory issue. This memory setting is for each driver in Agent machines that gets intialised when you kick of the test. The test can carry on if these drivers have more power in terms of memory and CPU. The memory for each of the agent can be specified by passing on parameter RPT_VMARGS

• Open the agent controller location  in the workspace by double clicking it.
• Then define new parameter as shown below which means the JVM heapsize for driver on agent machine is 1500MB. The maximum value it can take (as of with RPT 8.2 version ) is 3000MB. If you have big server with huge memory and multiple processors, then you might want to run more agents on these machine because, 3000MB limit of JVM settings will cut down advantage for you from using all the power of agent machine. On How to run multiple agents on one machine, you can refer my other blog How to setup Mutliple agents

• Apart from number of users, the other things that have implication on this memory are , large gif file, long script, responses that take long time, SSL connections.