To ensure the quality of the software product different tests has been performed. Once such test is Load Testing. Load Testing is a kind of Performance Testing that helps in determining how the application behaves when multiple users/requests hit the application simultaneously.
From many tools helping us to resolve this, for now we will see how Apache JMeter (JMeter) an Open Source tool helps us to achieve this, what are the pros and cons using this tool.
What is JMeter and Why do we need
JMeter is an Open Source testing desktop based application. It is 100% pure Java application used as a performance testing tool for analysing and measuring the performance in variety of graphical reports.
We can perform load testing, stress testing and functional testing for the applications.
If there are any flaws in application such as buffer overflow, memory leaks using this we can easily simulate the situation in our own environment, and avoid the Prod issue surprises.
Using JMeter we can achieve all this easily, with minimum to no knowledge in coding. Yay!!
Installation
Please follow the below detailed steps on the installation of JMeter on the respective operating system.
Windows & Linux: https://jmeter.apache.org/usermanual/get-started.html
Mac: https://psychowhiz.medium.com/install-jmeter-on-mac-25531bc2b2ad
JMeter Supports
JMeter supports following and more types of the applications that can be tested with the tool.
Websites – HTTPS and HTTP
Web services – REST, SOAP and Graphql
Database servers
FTP servers
LDAP servers
Mail servers – SMTP, POP3, IMAP
TCP Servers
Elements of JMeter
There are different elements in JMeter each performing a task to achieve our goal. Below are few elements which will be important to know perquisites:
Thread Group: Collection of Threads, each thread represents one user accessing the application in the thread. Ideally it simulates one real user making one request to the application server. We can have multiple number of threads configured here.
Samplers: Type of request, such as FTP, HTTP, etc.
Listeners: Shows the results in different formats.
Configuration: Setup defaults and variables for later use by the samplers.
Assertions: Validate response from the server is expected or not.
Load Testing
Prerequisites
Here we will test Google Home Page
Open installed JMeter
Click File -> New
Update the Name to GoogleHomePageTestPlan
Click Save Icon # it will save as the .jmx file
Figure 1: Save the test plan into .jmx file
Step 1: Thread Group
In the Thread Group, we need to know about the below properties.
Number of Threads: N number of users connecting to the target URL
Ramp-Up Period: Allows to include delay while requests hitting the target, for example if we have 10 threads and 5 ramp-up period : the 10 requests should hit the target within 5 seconds adding 0.5 seconds delay between each request. This is primarily used when we don't want to over bun the server and as well as client. But if you want to do the Stress Testing try tweaking the property based on the use case.
- Loop Count: N number of time the test case to be executed, for example if you have number of threads 5 and loop count as 2, total 10 times the request will hit the target.
Figure 2: Difference between Thread count and Loop count
Credits: https://medium.com/skyshidigital/performance-testing-with-jmeter-for-dummies-541ea9171464
Steps:
Right Click GoogleHomePageTestPlan -> Add -> Threads (Users) -> Thread Group
Good practices to rename the name, readability matters. For this am updating the name as GoogleHomePageTestSearch
Update “Number of Threads (users)”: 5
Note: Please do not give more than 10, they might block us ;)
Figure 3: Thread group creation page
Step 2: Samplers
Right Click GoogleHomePageTestSearch -> Add -> Sampler -> HTTP Request
Lets rename again. Update the name with: GoogleHomePageTestSearchHTTPRequest
Update the below parameters
Server Name of IP: www.google.com
Port Number: None [optional]
Protocol (http): HTTP / HTTPS [optional]
Method: GET
Path: /search
Parameters:
Click Add
Name: q
Value: JMeter
Figure 4: HTTP Sampler creation page
For POST Method with JSON input
We can give input, under Body Data give the JSON format input
If needed you can add sure to add header details under “HTTP Header Manager” and authorization under “HTTP Authorization Manager”. Both are under GoogleHomePageTestSearch -> Add -> Config Element
Step 3: Listeners
Right Click GoogleHomePageTestSearchHTTPRequest -> Add -> Listener -> View Results Tree
Rename the name. Update the Name: GoogleHomePageTestSearchHTTPRequestResultTree
Click the Run -> Green Button
View the results in Sampler result, Response data and Request
Different types of charts are available to see the results crisply. And the link is https://www.edureka.co/blog/load-testing-using-jmeter/
Figure 5: Result page after execution of the Sampler
Step 4: Configuration – [optional]
As this step is optional, but we can take parameters to the search
Right Click GoogleHomePageTestSearchHTTPRequest -> Add -> Config Element -> User Defined
Setup the Variables
Figure 6: User defined variables page
Using the defined variable, we need to use it by enclosing it in ${<variable>}
Figure 7: Redefine value to use the user defined variable
After Run: Check the “q” is substituted with the defined variable and HTTP Request is also holding the “q” value
Figure 8: Result tree, the user defined variable has been used in the GET request
The same format can be used while Data Driven Testing, where in you would want to induce dynamic values to the service. We need to configure the CSV Data Set Config under Config Element.
Step 5: Assertions – [optional]
The response assertion control panel lets you pattern strings to be compared against various fields of the request or response
Right Click GoogleHomePageTestSearchHTTPRequest -> Add -> Assertions -> Response Assertion
Setup the Validations: Positive Validation: Checking whether the Response Code is 200
Figure 9: Define the rules to evaluate response from the Sampler execution
Result would be positive, as we have that Response Code is 200
Figure 10: Response is 200, hence the test result is shown passed (green)
There are many different combination of assertions, including by adding regex rather hard coded values.
Bonus Step
We all like Bonus!!
Record and Run
Let's say we have many rest apis to be tested in single page, we got to create so many Samplers manually, which we will get bored doing. For example in Amazon, there will several api hit to form the Home Page, such as Deals, Products, Best Sellers, User Menu and so many others.
Here we have a solution to Record and Run. Shared the step by step example in the below reference link. Link is:
https://jmeter.apache.org/usermanual/jmeter_proxy_step_by_step.pdf
Note: For now Firefox browser supports this feature. Also we need to make sure we have access to update the settings in the Firefox.
Command Line
You can run the JMeter from the command line, and can have its output redirected to an html as well. The non GUI mode brings in more flexibility when running heavy loads. But the configuration can be still done using the GUI, as well the results can be analyzed.
Sample Command : $ jmeter -n -t GoogleHomePageTestSearch.jmx -l GoogleHomePageTestSearch.jtl -e -o googletestoutput
-n: to run in non-gui mode
-t: name of JMX file having the Test Plan
-l: Name of JTL(JMeter text logs) file to log results
-e: generate report dashboard after load test
-o: output folder where to generate the report dashboard after load test. Folder must not exist or be empty
Output:
Figure 11: HTML output of the command line execution
Pros of JMeter
Open Source: JMeter is an open source software, so no licensing costs
Ease to Use: The user can install and use JMeter easily
Platform independent: As JMeter is 100% Java based, so it is platform independent and can run on multiple platforms.
Customisable: Since JMeter is open source, developers can customize its source code as per their specific requirements. Also there is prescript and postscript execution process where we can run customisable code in Java or Jpython.
Data driven testing: The CSV Data Set Config, allows you to read different parameters from text file and convert into parameters which can be used in making dynamic requests.
Record and Playback: JMeter provides record and playback options alone with drag and drop feature which makes it easier and faster to create scripts.
Supports distributed load testing: JMeter supports distributed load testing features in which we can create master-slave setup for carrying out load test on multiple machines. Link is : https://jmeter.apache.org/usermanual/jmeter_distributed_testing_step_by_step.html
Good community support and Documentation: JMeter has many online tutorials(edureka I really like) and helping community support. It also has freely available plugins that helps in different aspects of script creation and analysis.
Reporting: Helps to visualise test results. As see before, test results can be displayed in a different format such as chart, table, tree, log file, html and etc.
Cons of JMeter
Passwords are saved as plain text, involves risk when the JMX file is accidentally shared
It supports only Java or Java backed languages for custom coding
Other Similar Tools
LoadView
LoadUI
NeoLoad
WEBLOAD
LoadRunner
Conclusion
One of the most used tool for performance and api testing. Definitely can be used to make sure the web applications are meeting the performance benchmarks.
The feature list of JMeter is exhaustive, this is just a sample of its usage.
The User Manual will have the detailed description of each its features, link is https://jmeter.apache.org/usermanual/index.html
References
https://www.edureka.co/blog/load-testing-using-jmeter/
https://jmeter.apache.org/usermanual/get-started.html
https://www.guru99.com/jmeter-tutorials.html
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