Listeners in Apache JMeter Tool (Load & Performance Testing Tool)

Listeners:

Definition: Listener is a component that shows the results of the samples which is used for analyzing and reporting results.

Different ways to add Listeners:

1. Add a Listener in Thread Group(Right Click on Thread Group→ Add → Listener → <Required Listener> For ex – View Results in Table)

2. Add a listener in Sampler (Right Click on Sampler→ Add → Listener → <Required Listener> For ex – View Results in Table)

Type of Listeners:

1. View Results Tree

2. View Results in Table

3. Summary Report

4. Aggregate Report

5. Aggregate Graph

6. Assertion Results

7. Comparison Assertion Visualizer

8. Graph Results

9. Response Time Graph

10. Simple Data Writer

11. Generate Summary Results

Important Terms:

Throughput: Throughput is a measure of requests/unit of time.

The calculation of time begins from the start of the first sample to the end of the last one. Basically, it is the amount of transactions happened over test duration.

Standard Deviation: How response time is spread around the mean. The smaller the SD response time is more consistent.

The standard deviation (σ) measures the mean distance of the values to their average (μ).It gives you a good idea of the dispersion or variability of the measures to their mean value.

The following equation show how the standard deviation (σ) is calculated:

σ = 1/n * √ Σi=1…n (xi-μ)2

Connect Time: Time taken to establish TCP connection b/w client and server using TCP Handshake. If TCP Handshake is successful, then the client can send further requests (HTTP request - HTTP layer). If not, the client can't talk to the server.

Latency: Meter?measures the latency from just before sending the request to just after the first response has been received. Thus the time includes all the processing needed to assemble the request as well as assembling the first part of the response, which in general will be longer than one byte.

Time we started getting first byte of the response.