Performance Testing, LoadRunner Tips&Tricks

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General: Scenario Execution

What happens when the scenario is executed? Here, we will discuss the basic overview when the scenario starts execution, during and end.

Prior to the scenario execution, the Load Generators, number of Vusers, the designated monitoring machine, the ramp up timing, so on so forth should be already defined, and we will skip the discussion for it.
When the scenario starts executing, the Controller dispatches the Vusers (scripts) to the designated Load Generator for execution. The Vusers are then executed on the Load Generator with the pre-defined amount on behalf of the Controller. The data generated by the Load Generator prior Collation process (discussed later) is stored in its default temp directory. This can be configured before the execution under the Load Generator setup.

Note that if your load test stretches a (1) long duration, (2) contain additional logs or (3) you foresee a large amount of data to be generated, it is advisable to ensure that you have sufficient space for the temp directory in the Load Generator. This also applies to the Controller temp directory. Either increase the disk size for the temp folder or direct it to a folder that has a larger space.
The temp directory of the Controller and Load Generator serves different purposes. For the Controller, it stores the entire result data of the scenario execution whereas, the Load Generator stores the data of its own during the scenario execution.

During the execution, the real time data of the monitored servers are displayed at the same time displayed in the graphs. This information is logged for further processing when conducting the analyzing.

Point to note; as the scripts are sent to the Load Generator to be executed, it must have the same environmental settings of the recorded scripts (in VuGen). For example, if the script was recorded in RMI-Java, JDK exists on the machine that performed the recording. In the same context, the Load Generator will also require the JDK to exist on it for the script to execute properly.

Another example is an activity of uploading of a file by the script. If the script points to a directory that only exists in the recording machine, the Load Generator will require to create the same directory for it to be executed correctly.

When errors start to occur during a scenario execution, it is best to determine where the error surface in the following questions.

1. Does it happen at the start of the scenario execution?
2. Does it happen at the middle of the scenario execution?
3. If (2), is yes, then how many Vusers were running at that point of time when the errors appeared?

With the above, you can guess if the scenario is actually failing due to the following reasons to list a few.

1. The script is not working properly in the first place or configuration of the script failed.
2. The application is experiencing load during the scenario execution.
3. Network/server issues not pertaining to load have occured during the scenario execution.

When the scenario completes, either (1) the Vusers finished execution, (2) you pressed the "Stop" button or (3) the duration of the load test have reached, the Vusers will gradually exit the scenario. Once all Vusers totally exited, the Controller goes into a Collation process.

In the Collation process, data regarding the execution stored in the temp directory of the Load Generator are been sent back to the Controller to be compiled to one single result data. This is stored in the default folder of the temp directory in Controller, usually in C:\Documents and Settings with the folder name res. The actual file that describes the result is stored as .lrr file extension.

Based on the scenario configuration, the Analysis maybe launched automatically for you to analyze the results directly after the scenario completes. However, you can also choose to launch it manually by double clicking the .lrr file.

With the above, it concludes the entire scenario execution process.

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