In JMeter there are number of listeners available in order to monitor and analyse the results in different parameters and statistics. We need to add an appropriate listener to analyse results which is difficult part of the performance testing. In the below example we will add 'Graph Result' listener. Graph Results listener presents data, average, median, deviation and throughput in a graphical format.
Please do not use listeners during the load test as it consume loads of resources and produce unreliable load test results. You can use when developing and debugging tests.
JMeter Graph Results Listener Example:
Step 1: Right Click Test Plan>Add>Threads(Users) > Thread Group.
Set Values as Number of Threads as 1000, Ramp-Up Period as 1 and Loop Count value as 1.
Step 2: Thread Group > Add > Sampler > HTTP request
Set Server Name as: amazon.com and Set Path as: /
Step 3: Thread Group > Add > Listener > Graph Results
Step 4: Save the Test Plan and Run
Graph Result shows the graph plotted. The x-axis contains the nth sampler and y-axis is the response time. The data, average, median, deviation and throughput are displayed as legends.
Green - Current Throughput Rate
Black - Current Sampler
Blue - Current Average of all Samples
Red - Current Standard deviation
Throughput is measured in requests/transaction per second/minute/hour the server handled. i.e.. Throughput = (number of requests) / (total time). The time is calculated from the start of the first sample to the end of the last sample.
Average - Average response time between request sent and getting reply response from server.
No of Samples - Total number of requests sent to server during the load test.
Deviation - Shows how much the response time varies. Deviation value should always be as low as possible. Higher values generally means system is under stress.
We will discuss more in details about how to analyse these values in coming tutorials.