Another often used listener in JMeter is the Aggregate Report listener. This listener creates a row for each uniquely named request in the test plan. Each row gives a summarized view of useful information including Request Count, Average, Median, Min, Max, 90% Line, Error Rate, Throughput, Requests/second, and KB/sec. The 90% Line column is particularly worth paying close attention to as you execute your tests. This figure gives you the time it takes for the majority of threads/users to execute a particular request. It is measured in milliseconds. Higher numbers here are indicative of slow requests and/or components within the application under test.

Equally important is the Error % column, which reports the failure rate of each sampled request. It is reasonable to have some level of failure when exercising test runs, but too high a number is an indication of either errors in scripts or certain components in the application under test. Finally, of interest...