Load Runner is a performance testing tool from Micro Focus, widely used for detecting performance bottlenecks in websites.
It is basically used to test the performance and behavior of a system under heavy load.

The VuGen (Virual User Generator) component is used to record a script. It allows you to implement Vuser scripts for a variety of application types and communication protocols.

Log files are crucial for troubleshooting the script. The logging of errors is enabled only after a script has been launched.
There are two types of Vuser logs in LoadRunner.

•  Standard Logs
• Extended Logs

• loadrunner automatically records the performance of the client/server during the test.
• loadrunner checks where performance delays occur network/client delays.
• loadrunner monitors the network and server resources to help improve performance.

• Controller manages and maintains the scenario. Using a controller you control all the vuser in a single workstation .

Industry standard protocols for example HTTP and ODBC are explicitly supported by LoadRunner. Furthermore any protocol that communicates over a windows socket can be supported.

An extended log will store information such as data returned by server and advanced trace, parameter substitution and much other information depending on the options you select in run-time settings.

•  lr_error_message: Sends a error message to the LoadRunner Controller’s Output window
• lr_debug _message: Sends a debug message to the LoadRunner Controller’s Output window

Performance Bottlenecks can be detected by using monitors. These monitors might be application server monitors, web server monitors, database server monitors and network monitors. They help in finding out the troubled area in our scenario which causes increased response time. The measurements made are usually performance response time, throughput, hits/sec, network delay graphs, etc.

A set of rules that enable Computer devices to connect and transmit data to one another. Protocols determine how data are transmitted between computing devices and over networks.