How to Access Session Variables Across Scenarios in Gatling

Discover how to effectively share session variables between different scenarios in Gatling using ConcurrentHashMap. Learn best practices and tips!
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How to Access Session Variables Across Scenarios in Gatling

When working with performance testing tools like Gatling, developers often face unique challenges in managing shared data efficiently. A common issue arises when attempting to access session variables generated in one scenario from another. In this guide, we'll explore a practical solution to this problem and ensure that your testing processes run smoothly and effectively.

The Problem: Sharing Session Variables

Imagine you're working with three different scenarios in your Gatling tests: Scenario A, Scenario B, and Scenario C. Here's how they typically flow:

Scenario A generates essential data that Scenario B and Scenario C require for execution.

Scenario B and Scenario C run in parallel after the completion of Scenario A.

You may be implementing the andThen() function to orchestrate their execution, but you find that accessing the session variables set in Scenario A from B and C poses a challenge. Unfortunately, because of the way Gatling handles sessions—each scenario has its own separate session—you won't be able to access the session data directly across different scenarios.

Why Can't You Access Session Variables Directly?

Each session in Gatling is tied to an individual virtual user. This means that when you execute different scenarios, they operate on unique virtual users, preventing them from sharing session data. Attempting to access a session variable from one scenario while already being in another scenario is not permitted, hence the issue you’re experiencing.

The Solution: Using ConcurrentHashMap

To effectively share data between scenarios, the recommended approach is to use a ConcurrentHashMap. With this method, you can maintain shared data that various scenarios can reference without being limited by Gatling's session management.

Step-by-Step Guide to Using ConcurrentHashMap

Import the Required Libraries: Ensure to import the ConcurrentHashMap class in your Gatling script.

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Declare the Shared Map:

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Update the Shared Map in Scenario A:
After generating your required value in Scenario A, store it in the ConcurrentHashMap.

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Access the Shared Data in Scenarios B and C:
Retrieve the required value in your subsequent scenarios.

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Set Up Your Scenarios:
Finally, structure your scenarios using the setUp() method with andThen() to maintain their execution order.

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Conclusion

Managing session data effectively across multiple scenarios in Gatling may initially seem complex. However, by leveraging a ConcurrentHashMap, you can efficiently share values generated in one scenario with subsequent ones. This approach not only enhances your performance tests but also keeps your code organized and maintainable.

Feel free to implement this solution in your future Gatling tests and enjoy the seamless data sharing it offers! If you have any other questions on Gatling or performance testing, don't hesitate to reach out!

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