LoadRunner Scripting Challenges with Solutions for Beginners
Scripting in LoadRunner is tricky, particularly when handling dynamic data such as session IDs and correlation problems that lead to test failure. Other typical LoadRunner scripting challenges involve dealing with large-scale test scenarios and unforeseen errors on replay. To overcome these, there must be extensive knowledge of key concepts such as correlation, parameterization, and useful debugging methodologies.
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LoadRunner Scripting Challenges with Solutions
Here are the top LoadRunner Scripting challenges and solutions:
Dynamic Data Correlation
Challenge: Scripts malfunction when replayed due to dynamic, dynamic values (such as session IDs, timestamps, or tokens) produced by the server. Values must be recorded from an initial response and inserted into a following request.
Solution: Correlate. In LoadRunner, that means locating the dynamic value, capturing its value with a correlation function (web_reg_save_param_ex is a modern, flexible choice), and then substituting the hardcoded value in the following request with a parameter.
Code Example: C
// Capture the dynamic session ID from the login response
web_reg_save_param_ex(
“ParamName=c_session_id”,
“LB=sessionId=”,
“RB=;”,
“NotFound=warning”,
SEARCH_FILTERS,
“Scope=BODY”,
“IgnoreEmbeddedResources=1”,
LAST);
// Use the captured value in the next request
web_url(“next_page”,
“URL=http://example.com/next_page?sessionId={c_session_id}”,
LAST);
Real-time Example: A user enters a web application, and the server creates a new session ID. This ID needs to be incorporated in every following request so that the session is still valid.
Application: e-commerce websites, banking portals, and any web application with sessioned users.
Parameterization Challenge in LoadRunner
Challenge: Replaying the same script with the same hardcoded data (e.g., username, password) to replay to different virtual users. This is not a real test scenario and could cause cache hits, skewing performance results.
Solution: Parameterization. Substitute constant values with variables drawn from an external data file (such as a CSV). This enables each virtual user to utilize distinct data within the test execution.
Code Example: C
// Assume the parameter file “login_data.dat” has columns User and Password
// The file is configured in the LoadRunner Controller
web_submit_data(“login.jsp”,
“Action=http://example.com/login.jsp”,
“Method=POST”,
“RecContentType=text/html”,
“Referer=http://example.com/”,
“Snapshot=t1.inf”,
“Mode=HTML”,
ITEMDATA,
“Name=username”, “Value={User}”, ENDITEM,
“Name=password”, “Value={Password}”, ENDITEM,
LAST);
Real-time Example: 1,000 users logging in with 1,000 distinct usernames and passwords.
Application: Any performance test involving distinct user data, such as logins, product searches, or data entry forms.
Recommended: LoadRunner Course Online.
Handling Asynchronous Calls (AJAX)
Challenge: New web applications extensively utilize asynchronous JavaScript and XML (AJAX) to load content dynamically without full page refresh. LoadRunner’s default recording may not record such requests properly, resulting in test scripts that are incomplete.
Solution: Modify the recording options to accommodate AJAX. LoadRunner’s TruClient protocol is built-in for such applications, but with Web (HTTP/HTML) protocol, web_custom_request can be used to manually script the AJAX requests or web_reg_find can be utilized to wait for certain content to show up.
Code Example: C
// Manually script an AJAX request
web_custom_request(“get_data”,
“URL=http://example.com/api/getData”,
“Method=GET”,
“Resource=0”,
“RecContentType=application/json”,
“Mode=HTML”,
“ExtraRes=0”,
“EncType=application/json”,
LAST);
Real-time Example: Clicking a “Load More” button on a social media timeline or a flight search form that fills in without refreshing the page.
Application: Single-page applications (SPAs), rich internet applications (RIAs), and sites using frameworks like React, Angular, or Vue.js.
SSL/TLS Handshake and Certificate Issues
Challenge: Scripts fail with SSL errors (ssl_handshake_error) because LoadRunner can’t establish a secure connection with the server. This often happens with self-signed certificates or when the script’s security settings don’t match the server’s.
Solution: When recording, have the recording options configured to record on a particular port if SSL is on an alternate port. In the runtime settings, configure the SSL_VERSION according to the server protocol (e.g., TLSv1.2) and possibly disable certificate checks.
Real-time Example: Recording an internal company portal that uses a self-signed security certificate.
Application: Any application with HTTPS (Secure Hypertext Transfer Protocol).
Recommended: LoadRunner Tutorial for Beginners.
Managing Think Times
Challenge: Thin scripts with no think times play back at machine rate, placing unrealistically heavy loads on the server. This does not mirror the way real users will actually behave.
Solution: Insert lr_think_time() statements between transactions. LoadRunner can insert them automatically while recording, or you can insert them manually to simulate the delay a real user would experience to read a page or complete a form.
Code Example:
web_submit_data(“login.jsp”,
//… code for login request
LAST);
lr_think_time(5); // Wait for 5 seconds
web_url(“home_page”,
//… code for navigating to home page
LAST);
Real-time Example: A user reads a login page in 5 seconds before entering credentials and clicking the “login” button.
Application: All performance tests since think times are needed for simulating realistic user behavior.
Error Handling in LoadRunner
Challenge: Scripts crash or fail without helpful diagnostic information when a transaction fails (e.g., a page doesn’t load or an expected element isn’t found).
Solution: Have good error handling. Utilize functions such as lr_abort() to abort a Vuser on a critical error and web_reg_find to ensure that certain text or content is visible on the page. Utilize lr_error_message() for friendly error messages.
Code Example:
web_reg_find(“Text=Thank you for your order!”, “Fail=NotFound”, LAST);
web_submit_data(“order_submission”,
//… code for submitting order
LAST);
Real-time Example: A “Thank You” page should be presented after a transaction, but a server error page is displayed.
Application: Important business processes such as order submission, account creation, or payment transactions.
Recommended: LoadRunner Interview Questions and Answers.
Handling Caching and Cookies
Challenge: LoadRunner scripts, by default, do not mimic a real browser, which caches static resources (images, CSS, JS files) and handles cookies automatically. This can result in scripts that generate an unrealistic load.
Solution: Set runtime settings. LoadRunner provides a mechanism to record a new user for every iteration (clearing cookies and cache) or to simulate a returning user. For static resources, one simple solution is disabling their recording or using the “Do not cache” option.
Real-time Example: A returning user to a site that previously cached CSS files.
Application: Any web performance test where caching behavior plays a role.
Dealing with Non-Standard Character Sets
Challenge: Scripts can fail or transmit jumbled data to the server if the application is utilizing a character set such as UTF-8, but the script is transmitting data in another form.
Solution: Use the web_set_sockets_option() function to set the character set manually (“Character_Set=UTF-8”). You might also need to set the script to use the proper encoding.
Code Example: C
web_set_sockets_option(“Character_Set=UTF-8”);
Real-time Example: An e-commerce website with product names that have characters from multiple languages.
Application: Internationalized applications and those that involve non-ASCII characters.
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Database Query Parameterization
Challenge: Testing a database-hungry application using the same queries may produce misleading results due to database caching.
Solution: Parameterize your database queries. If you are using LoadRunner database protocols, then you can substitute hardcoded values within SQL statements with parameters from a data file.
- Real-time Scenario: Emulating a customer lookup function in which every Vuser looks up a different customer ID.
- Use Case: Enterprise Resource Planning (ERP) applications, Customer Relationship Management (CRM) software, and any application that initiates direct calls to a database.
Replay Log and Debugging
Challenge: It is sometimes hard to determine the precise reason a script does not run, particularly for complex scripts.
Solution: Use the replay log. LoadRunner gives an extensive log of all the requests and responses. Set the log level to “Extended” and turn on “Data and Headers” to get all the data sent and received, which is very important for determining correlation issues or miscalculated data. The VuGen debugger is another good tool for stepping through the script.
- Real-time Scenario: A script crashes at a particular step, and the replay log indicates there is a correlation parameter that is empty, meaning the dynamic value failed to be captured appropriately.
- Application: A problem and solution that applies across all LoadRunner scripting.
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Conclusion
Successfully tackling LoadRunner scripting difficulties—ranging from dynamic data correlation to asynchronous call handling—is imperative to precise and dependable performance testing. Having the skills to master these methods turns an awkward undertaking into a manageability, having your tests mimic real-user activity.
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