Performance Testing and Engineering

1. Ensure that time slot is booked in calendar on your project name.
2. Check that application is working manually.
3. Check whether the entire server’s are up and in normal condition.
4. If in SiteScope the values against summary of any server are ‘NA’ then restart those servers.
5. If time permits run each script individually for five iterations in VuGen.
6. Refresh the script in Performance Center with the latest version.
7. Check the runtime settings of each script.
8. Check the scenario settings and number of users configured for each script with workload Model.
9. Check for IP Spoofing whether enabled or disabled and change it as per the requirement.
10. Before starting the scenario verify that each script duration, ramp up and ramp down time is correct.
11. Check whether Monitor profiles are configured correctly.
12. Check whether windows profilers are added.
13. Book the same time slot in Performance Center and manually select Load Generators and Controller.
14. Configure number of Load Generator, Controller as per allocated in time slot and take only those Generators and Controller, which are free.
15. When ready to run the test send an alert mail to all related groups.

Using minimal hardware resources, HP Performance Center lowers the cost of distributed load testing by providing a standard solution that can be managed via the web.

This integrated performance validation solution emulates hundreds or thousands of concurrent users to apply simulated production workloads to virtually any client platform or environment. Using Performance Center, testing teams can stress an application from end to end—applying consistent, measurable and repeatable loads—and then use the data to identify scalability issues that could impact users. HP Performance Center:

• Lowers the cost of distributed load testing

• Reduces the risk of deploying systems that do not meet your performance requirements

Creating Load Test

1. Launch Performance Center link.
2. Under Load Test tab click on Manage and then to create new load test click on New Load Test
3. To manage load test, there are four tabs General, Workload, Monitors, Diagnotics.
4. In General tab, we specify load test name and description like type of test (baseline, benchmark), number of Vusers
5. In Workload tab, there are four types of scenario, most of the time we choose Basic Schedule, by load test and Vuser distribution option as by number.
6. Like LoadRunner Controller, there are many tabs to manage scenario.
7. In the Scripts tab, you can Add Scripts, Vusers, Load Generators.
8. In Global Schedule tab, you mention the properties like Initialize, Start Vusers (Ramp Up), Duration of the test run and Stop Vusers (Ramp Down).
9. To apply same runtime setting to all groups, Click on Duplicate Runtime Settings and select source group and target group to apply runtime settings.
10. For managing load generators, click on LG Distribution, choose Manual Distribution, under that choose Assign Actual LG to groups.
11. Select load generators.
12. To add and edit monitors, click on Monitors tab
13. To add monitors click on Add Profile, create New Profile.
14. Specify Profile name and description like App Server, Web Services, Database Server
15. Choose monitor like Windows Resources, under System Resources graph.
16. Choose Server which you want to monitor, provide server name, username, password for that server.
17. Select the Measurements like Page Faults/Sec, Processor Time.
18. In Diagnostic tab, enable the diagnostic.
19. Specify value for Perform diagnostic breakdown on X %.
20. Enable Web Page diagnostic of all relevant Vusers.

You use the LoadRunner Controller to manage and maintain your scenarios. Using the Controller, you control all the Vusers in a scenario from a single workstation.

Creating the Scenario

A scenario describes the events that occur during a testing session. A scenario includes a list of machines on which Vusers run a list of scripts that the Vusers run, and a specified number of Vusers or Vuser groups that run during the scenario. You create scenarios using the LoadRunner Controller.

Creating a Manual Scenario

You create a scenario by defining Vuser groups to which you assign a quantity of individual Vusers, Vuser scripts, and load generators to run the scripts.

You can also create a scenario using the Percentage Mode, in which you define the total number of Vusers to be used in the scenario, and the load generator machines and percentage of the total number of Vusers to be assigned to each Vuser script.

Creating a Goal-Oriented Scenario

For Web tests, you can create a goal-oriented scenario, in which you define the goals you want your test to achieve. LoadRunner automatically builds a scenario for you, based on these goals.

Creating Sample Scenario

1. Launch LoadRunner

2. Under Load Testing tab, select Run Load Tests

3. To manage your load test by specifying the number of virtual users to run, select Scenario type as Manual Scenario

4. Add scripts to scenario and click Ok.

5. Look at the Scenario Groups, here you can add more scripts, edit Vusers quantity, add load generators, edit Runtimes Settings.

6. Then work on Scenario Schedule, specify Schedule name, according to test plan Choose Schedule type , and Run Mode

7. Then work on Global Schedule, keep properties for Initialize as it is.

8. Set Start Vusers properties depending on the ramp up required.

9. Specify Duration of test run.

10. Set Stop Vusers properties depending on the ramp down required.

11. You can see the graphical representation of the created scenario.

12. When you are done with Scenario Design part click on Run which is located at bottom of the page.

13. To add Windows Resources go to Available Graphs, Under System Resource Graphs, choose Windows Resources

14. To add Measurements, right click on Windows Resources, and choose Add Measurements.

15. In the Windows Resources pop-up, click on Add button, in the new pop-up specify Machine Information, like name and platform.

16. Select the Resource Measurements and click on add button, and add the resource.

17. Click on Start Scenario.

18. Now controller will start running your designed scenario.

19. When test is running you can monitor the Windows Resources and Test Status with respect to Transactions passed, failed and Errors occurred while running.

20. You can see the detail status of transaction passed and failed by click on mirror right next to Passed Transactions and Failed Transactions

21. You can see the errors thrown by web app by clicking on mirror right next to Errors

22. While test is running, if you want to Add Vusers, you can do that by clicking on Add Vusers Tab.

23. Select group name, quantity to add, load generators name and script name.

24. You can see the Test results by clicking on Analysis icon.

P.S. : Thanks to Bhanu Prakash.

1. What is load testing? – Load testing is to test that if the application works fine with the loads that result from large number of simultaneous users, transactions and to determine whether it can handle peak usage periods.
2. What is Performance testing? – Timing for both read and update transactions should be gathered to determine whether system functions are being performed in an acceptable timeframe. This should be done standalone and then in a multi user environment to determine the effect of multiple transactions on the timing of a single transaction.
3. Did u use LoadRunner? What version? – Yes. Version 9.5.
4. Explain the Load testing process? –
   Step 1: Planning the test. Here, we develop a clearly defined test plan to ensure the test scenarios we develop will accomplish load-testing objectives. Step 2: Creating Vusers. Here, we create Vuser scripts that contain tasks performed by each Vuser, tasks performed by Vusers as a whole, and tasks measured as transactions. Step 3: Creating the scenario. A scenario describes the events that occur during a testing session. It includes a list of machines, scripts, and Vusers that run during the scenario. We create scenarios using LoadRunner Controller. We can create manual scenarios as well as goal-oriented scenarios. In manual scenarios, we define the number of Vusers, the load generator machines, and percentage of Vusers to be assigned to each script. For web tests, we may create a goal-oriented scenario where we define the goal that our test has to achieve. LoadRunner automatically builds a scenario for us. Step 4: Running the scenario.
   We emulate load on the server by instructing multiple Vusers to perform tasks simultaneously. Before the testing, we set the scenario configuration and scheduling. We can run the entire scenario, Vuser groups, or individual Vusers. Step 5: Monitoring the scenario. We monitor scenario execution using the LoadRunner online runtime, transaction, system resource, Web resource, Web server resource, Web application server resource, database server resource, network delay, streaming media resource, firewall server resource, ERP server resource, and Java performance monitors. Step 6: Analyzing test results. During scenario execution, LoadRunner records the performance of the application under different loads. We use Loadrunner’s graphs and reports to analyze the application’s performance.
5. When do you do load and performance Testing? – We perform load testing once we are done with interface (GUI) testing. Modern system architectures are large and complex. Whereas single user testing primarily on functionality and user interface of a system component, application testing focuses on performance and reliability of an entire system. For example, a typical application-testing scenario might depict 1000 users logging in simultaneously to a system. This gives rise to issues such as what is the response time of the system, does it crash, will it go with different software applications and platforms, can it hold so many hundreds and thousands of users, etc. This is when we set do load and performance testing.
6. What are the components of LoadRunner? – The components of LoadRunner are The Virtual User Generator, Controller, and the Agent process, LoadRunner Analysis and Monitoring, LoadRunner Books Online.
7. What Component of LoadRunner would you use to record a Script? – The Virtual User Generator (VuGen) component is used to record a script. It enables you to develop Vuser scripts for a variety of application types and communication protocols.
8. What Component of LoadRunner would you use to play back the script in multi user mode? – The Controller component is used to playback the script in multi-user mode. This is done during a scenario run where a Vuser script is executed by a number of Vusers in a group.
9. What is a rendezvous point? – You insert rendezvous points into Vuser scripts to emulate heavy user load on the server. Rendezvous points instruct Vusers to wait during test execution for multiple Vusers to arrive at a certain point, in order that they may simultaneously perform a task. For example, to emulate peak load on the bank server, you can insert a rendezvous point instructing 100 Vusers to deposit cash into their accounts at the same time.
10. What is a scenario? – A scenario defines the events that occur during each testing session. For example, a scenario defines and controls the number of users to emulate, the actions to be performed, and the machines on which the virtual users run their emulations.
11. Explain the recording mode for web Vuser script? – We use VuGen to develop a Vuser script by recording a user performing typical business processes on a client application. VuGen creates the script by recording the activity between the client and the server. For example, in web based applications, VuGen monitors the client end of the database and traces all the requests sent to, and received from, the database server. We use VuGen to: Monitor the communication between the application and the server; Generate the required function calls; and Insert the generated function calls into a Vuser script.
12. Why do you create parameters? – Parameters are like script variables. They are used to vary input to the server and to emulate real users. Different sets of data are sent to the server each time the script is run. Better simulate the usage model for more accurate testing from the Controller; one script can emulate many different users on the system.
13. What is correlation? Explain the difference between automatic correlation and manual correlation? – Correlation is used to obtain data which are unique for each run of the script and which are generated by nested queries. Correlation provides the value to avoid errors arising out of duplicate values and also optimizing the code (to avoid nested queries). Automatic correlation is where we set some rules for correlation. It can be application server specific. Here values are replaced by data which are created by these rules. In manual correlation, the value we want to correlate is scanned and create correlation is used to correlate.
14. How do you find out where correlation is required? Give few examples from your projects? – Two ways: First we can scan for correlations, and see the list of values which can be correlated. From this we can pick a value to be correlated. Secondly, we can record two scripts and compare them. We can look up the difference file to see for the values which needed to be correlated.  In my project, there was a unique id developed for each customer, it was nothing but Insurance Number, it was generated automatically and it was sequential and this value was unique. I had to correlate this value, in order to avoid errors while running my script. I did using scan for correlation.
15. Where do you set automatic correlation options? – Automatic correlation from web point of view can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation. Automatic correlation for database can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.
16. What is a function to capture dynamic values in the web Vuser script? – Web_reg_save_param function saves dynamic data information to a parameter.
17. When do you disable log in Virtual User Generator, When do you choose standard and extended logs? – Once we debug our script and verify that it is functional, we can enable logging for errors only. When we add a script to a scenario, logging is automatically disabled. Standard Log Option: When you select
    Standard log, it creates a standard log of functions and messages sent during script execution to use for debugging. Disable this option for large load testing scenarios. When you copy a script to a scenario, logging is automatically disabled Extended Log Option: Select
    extended log to create an extended log, including warnings and other messages. Disable this option for large load testing scenarios. When you copy a script to a scenario, logging is automatically disabled. We can specify which additional information should be added to the extended log using the extended log options.
18. How do you debug a LoadRunner script? – VuGen contains two options to help debug Vuser scripts-the Run Step by Step command and breakpoints. The Debug settings in the Options dialog box allow us to determine the extent of the trace to be performed during scenario execution. The debug information is written to the Output window. We can manually set the message class within your script using the lr_set_debug_message function. This is useful if we want to receive debug information about a small section of the script only.
19. How do you write user defined functions in LR? Give me few functions you wrote in your previous project? – Before we create the User Defined functions we need to create the external library (DLL) with the function. We add this library to VuGen bin directory. Once the library is added then we assign user defined function as a parameter. The function should have the following format: __declspec (dllexport) char* <function name>(char*, char*)Examples of user defined functions are as follows:GetVersion, GetCurrentTime, GetPltform are some of the user defined functions used in my earlier project.
20. What are the changes you can make in run-time settings? – The Run Time Settings that we make are: a) Pacing – It has iteration count. b) Log – Under this we have Disable Logging Standard Log and c) Extended Think Time – In think time we have two options like Ignore think time and Replay think time. d) General – Under general tab we can set the Vusers as process or as multithreading and whether each step as a transaction.
21. Where do you set Iteration for Vuser testing? – We set Iterations in the Run Time Settings of the VuGen. The navigation for this is Run time settings, Pacing tab, set number of iterations.
22. How do you perform functional testing under load? – Functionality under load can be tested by running several Vusers concurrently. By increasing the amount of Vusers, we can determine how much load the server can sustain.
23. What is Ramp up? How do you set this? – This option is used to gradually increase the amount of Vusers/load on the server. An initial value is set and a value to wait between intervals can be specified. To set Ramp Up, go to ‘Scenario Scheduling Options’
24. What is the advantage of running the Vuser as thread? – VuGen provides the facility to use multithreading. This enables more Vusers to be run per generator. If the Vuser is run as a process, the same driver program is loaded into memory for each Vuser, thus taking up a large amount of memory. This limits the number of Vusers that can be run on a single
    generator. If the Vuser is run as a thread, only one instance of the driver program is loaded into memory for the given number of Vusers (say 100). Each thread shares the memory of the parent driver program, thus enabling more Vusers to be run per generator.
25. If you want to stop the execution of your script on error, how do you do that? – The lr_abort function aborts the execution of a Vuser script. It instructs the Vuser to stop executing the Actions section, execute the vuser_end section and end the execution. This function is useful when you need to manually abort a script execution as a result of a specific error condition. When you end a script using this function, the Vuser is assigned the status “Stopped”. For this to take effect, we have to first uncheck the .Continue on error. Option in Run-Time Settings.
26. What is the relation between Response Time and Throughput? – The Throughput graph shows the amount of data in bytes that the Vusers received from the server in a second. When we compare this with the transaction response time, we will notice that as throughput decreased, the response time also decreased. Similarly, the peak throughput and highest response time would occur approximately at the same time.
27. Explain the Configuration of your systems? – The configuration of our systems refers to that of the client machines on which we run the Vusers. The configuration of any client machine includes its hardware settings, memory, operating system, software applications, development tools, etc. This system component configuration should match with the overall system configuration that would include the network infrastructure, the web server, the database server, and any other components that go with this larger system so as to achieve the load testing objectives.
28. How do you identify the performance bottlenecks? – Performance Bottlenecks can be detected by using monitors. These monitors might be application server monitors, web server monitors, database server monitors and network monitors. They help in finding out the troubled area in our scenario which causes increased response time. The measurements made are usually performance response time, throughput, hits/sec, network delay graphs, etc.
29. If web server, database and Network are all fine where could be the problem? – The problem could be in the system itself or in the application server or in the code written for the application.
30. How did you find web server related issues? – Using Web resource monitors we can find the performance of web servers. Using these monitors we can analyze throughput on the web server, number of hits per second that
    occurred during scenario, the number of http responses per second, the number of downloaded pages per second.
31. How did you find database related issues? – By running Database monitor and help of Data Resource Graph. We can find database related issues. E.g. you can specify the resource you want to measure on before running the controller and then you can see database related issues.
32. Explain all the web recording options?Here you specify HTML or URL base recording.
33. What is the difference between Overlay graph and Correlate graph? – Overlay Graph: It overlay the content of two graphs that shares a common x-axis. Left Y-axis on the merged graph shows the current graph’s value & Right Y-axis show the value of Y-axis of the graph that was merged. Correlate Graph: Plot the Y-axis of two graphs against each other. The active graph’s Y-axis becomes X-axis of merged graph. Y-axis of the graph that was merged becomes merged graph’s Y-axis.
34. How did you plan the Load? What are the Criteria? – Load test is planned to decide the number of users, what kind of machines we are going to use and from where they are run. It is based on 2 important documents, Task Distribution Diagram and Transaction profile. Task Distribution Diagram gives us the information on number of users for a particular transaction and the time of the load. The peak usage and off-usage are decided from this Diagram. Transaction profile gives us the information about the transactions name and their priority levels with regard to the scenario we are deciding.
35. What does vuser_init action contain? – Vuser_init action contains procedures to login to a server.
36. What does vuser_end action contain? – Vuser_end section contains log off procedures.
37. What is think time? How do you change the threshold? –   Think time is the time that a real user waits between actions. Example: When a user receives data from a server, the user may wait several seconds to review the data before responding. This delay is known as the think time. Changing the Threshold: Threshold level is the level below which the recorded think time will be ignored. The default value is five (5) seconds. We can change the think time threshold in the Recording options of the VuGen.
38. What is the difference between standard log and extended log? – The standard log sends a subset of functions and messages sent during script execution to a log. The subset depends on the Vuser type Extended log sends a detailed script execution messages to the output log. This is mainly used during debugging when we want information about: Parameter substitution, Data returned by the server, advanced trace.
39. Explain the following functions: – lr_debug_message – The lr_debug_message function sends a debug message to the output log when the specified message class is set. lr_output_message – The lr_output_message function sends notifications to the Controller Output window and the Vuser log file. lr_error_message – The lr_error_message function sends an error message to the LoadRunner Output window. lrd_stmt – The lrd_stmt function associates a character string (usually a SQL statement) with a cursor. This function sets a SQL statement to be processed. lrd_fetch – The lrd_fetch function fetches the next row from the result set.
40. Throughput – If the throughput scales upward as time progresses and the number of Vusers increase, this indicates that the bandwidth is sufficient. If the graph were to remain relatively flat as the number of Vusers increased, it would
    be reasonable to conclude that the bandwidth is constraining the volume of
    data delivered.
41. Types of Goals in Goal-Oriented Scenario – Load Runner provides you with five different types of goals in a goal oriented scenario: 1)The number of concurrent Vusers, 2)The number of hits per second, 3)The number of transactions per second, 4)The number of pages per minute, 5)The transaction response time that you want your scenario
42. Analysis Scenario (Bottlenecks): In Running Vuser graph correlated with the response time graph you can see that as the number of Vusers increases, the average response time of the check itinerary transaction very gradually increases. In other words, the average response time steadily increases as the load
    increases. At 56 Vusers, there is a sudden, sharp increase in the average response
    time. We say that the test broke the server. That is the mean time before failure (MTBF). The response time clearly began to degrade when there were more than 56 Vusers running simultaneously.
43. What is correlation? Explain the difference between automatic correlation and manual correlation? – Correlation is used to obtain data which are unique for each run of the script and which are generated by nested queries. Correlation provides the value to avoid errors arising out of duplicate values and also optimizing the code (to avoid nested queries). Automatic correlation is where we set some rules for correlation. It can be application server specific. Here values are replaced by data which are created by these rules. In manual correlation, the value we want to correlate is scanned and create correlation is used to correlate.
44. Where do you set automatic correlation options? – Automatic correlation from web point of view can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation.  Automatic correlation for database can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.
45. What is a function to capture dynamic values in the web Vuser script? – Web_reg_save_param function saves dynamic data information to a parameter.

Execution is the process of executing the recorded script on the test environment. One can use LoadRunner Controller or Performance Center for managing load tests. Tests are carried out for various workloads as per the design of the test plan.

Performance test execution involves following activities:

1. Manually check if web application is up. You can do this by visiting the application link in internet explorer and going through any simple flow.
2. First validate all the scripts in VuGen with single iteration, see if scripts are working fine.
3. Upload all the scripts in Performance Center or LoadRunner.
4. Create test scenario according to the need.
5. Add controller and load generators.
6. Add monitors which are mentioned in test plan.
7. Enable or disable the Diagnostic according to the need.
8. Start the execution