How to increase available RAM on machine

We have talked in length about RAM, memory leakage and how to calculate memory requirements. The question is, what shall we do if we run out of RAM/memory?

The word increasing RAM is actually a misnomer. We all know RAM comes in the form of a chip and that is fixed, when we say increasing memory/RAM we mean to increase the Virtual memory associated with RAM. We have already seen that when a system runs out of spaceit allots some of the RAM to virtual memory . So can you increase this virtual memory?

1. Go to Start > Control Panel > System > Click on ‘Settings’ under Performance section.
2. Now go to advanced tab. Click ‘Change’ under Virtual Memory section.
3. Select the drive where your paging files reside. Generally they are present in C: drive. Change the value and click on ‘Set’.

The steps given above are for Windows XP professional. I believe steps for other OS will more or less be the same.

Points to note with VuGen and Controller

• When a script is opened in Controller, run-time settings also gets copied from VUGen to controller. Check out components of LoadRunner.
• Any changes done in the script and run-time settings are not reflected in the controller unless you refresh them.
• Refresh in controller can be done by going to Design > {Highlighting scenario group} that are using script in question > Clicking Details button > Clicking the REFRESH button on the Group Information pop-up window. So next time when controller asks you to load new script iteration settings do the refresh.
• While doing Save As:
  • Default directory in VUGen can be changed by going to vugen.ini file located under C:\Program Files\HP\LoadRunner\config and appending the required file path to LastScriptPath (as shown on the right).
  • Default directory in Controller can be changed by going to wlrun.ini file located under C:\Program Files\HP\LoadRunner\config and appending the required file path to M_ROOT
• Note that THINK time is ignored in VUGen while played back as recorded in Controller.

How to handle pop-up windows in Oracle NCA?

We will see step-by-step procedure of how to handle the pop-up windows while using Oracle NCA protocol:

1. Put the title of the pop-up window in nca_obj_status function.
2. Find out where the pop-up is occurring, put the handling statement below it.
3. The handling statement could be nca_popup_message_press ornca_message_box_press. To find out which function is suitable for your script, record a script using data that generates that popup window, click on the button and check which function gets recorded.

Example:

This piece of code will trigger a pop-up:

nca_set_window( "PopUpObjects");
 
nca_lov_retrieve_items("PopUpObjects",1,20);
 
nca_lov_select_item("PopUpObjects","POP UP NOTIFICATIONS");
 

If title of the window is “Warning”, put it inside the nca_obj_status function. The code would be something like-

int status;
 
status=nca_obj_status("Warning");
 
if (status = = 0)
 
nca_popup_message_press("Warning","OK");
 
// nca_message_box_press("Forms",1); Any one of them

Load Runner FAQs

1)Difference between concurrent and simultaneous vuser?

This is one of the most frequently asked questions from LoadRunner newbies. If we go by the literal meaning from Dictionary.Com both are same but from LoadRunner’s perspective there is a slight difference.

All the vusers in a particular scenario are called Concurrent vusers. They may or may not perform the same tasks. On the other hand simultaneous vusers is more to do withrendezvous points. When we set rendezvous points we instruct the system to wait till a certain no of vusers arrive so that they all can do a particular task simultaneously. These vusers performing the same task at the same time are called Simultaneous vusers.

For example in a Yahoo Mail application: Suppose a scenario consists of 100 vusers with 3 tasks – 1) Login, 2) Check no of unread mails 3) Logout. Vusers at 1) + 2) + 3) will be called as concurrent vusers as they are part of same scenario performing some task but if have set a rendezvous point so that say 25 vuser perform the 2) task at the same time these 25 vusers would be termed as simultaneous vusers.

2)What is memory leak, page fault and how they affect LoadRunner performance?

memory leak:

A memory leak is a particular type of unintentional memory consumption by a computer program where the program fails to release memory when no longer needed. This condition is normally the result of a bug in a program that prevents it from freeing up memory that it no longer needs.This term has the potential to be confusing, since memory is not physically lost from the computer. Rather, memory is allocated to a program, and that program subsequently loses the ability to access it due to program logic flaws.

page fault:

An interrupt that occurs when a program requests data that is not currently in real memory. The interrupt triggers the operating system to fetch the data from a virtual memory and load it into RAM.

An invalid page fault or page fault error occurs when the operating system cannot find the data in virtual memory. This usually happens when the virtual memory area, or the table that maps virtual addresses to real addresses, becomes corrupt.

Now the most important question comes up, how do they affect

LoadRunner functioning:

As you might guess, memory leak, if left unattended and not corrected, could prove to be fatal. Memory leaks can be found out by running tests for long duration (say about an hour) and continuously checking memory usage.

Issues caused by memory leaks are essentially based on two variable for a standalone windows application 1) Frequency of usage 2) size of memory leak . If either one or both are very high it could cause the computer to come to a point when no memory is available for other applications causing it to crash. If it is a network based application then you will also have to consider network traffic . If each network transaction causes a memory leak , then a high volume of network transactions could also prove dangerous.

Why Choose LoadRunner for Performance testing

This article start with brief introduction to Performance Testing, Why should you automate performance testing, What are the LoadRunner components, LoadRunner Terminology and Load Testing Process.

Performance Testing is the process by which software is tested and tuned with the intent of realizing the required performance.

The performance testing part of performance engineering encompasses what's commonly referred to as load, spike, and stress testing, as well as validating system performance. Performance can be classified into three main categories:

• Speed — Does the application respond quickly enough for the intended users?
• Scalability — Will the application handle the expected user load and beyond?
• Stability — Is the application stable under expected and unexpected user loads?

A well-constructed performance test answers questions such as:

• Does the application respond quickly enough for the intended users?
• Will the application handle the expected user load and beyond?
• Will the application handle the number of transactions required by the business?
• Is the application stable under expected and unexpected user loads?

By answering these questions, automated performance testing quantifies the impact of a change in business terms. This in turn makes clear the risks of deployment. An effective automated performance testing process helps you to make more informed release decisions, and prevents system downtime and availability problems.

What are the LoadRunner components?

LoadRunner contains the following components:

• The Virtual User Generator captures end-user business processes and creates an automated performance testing script, also known as a virtual user script.
• The Controller organizes, drives, manages, and monitors the load test.
• The Load Generators create the load by running virtual users.
• The Analysis helps you view, dissect, and compare the performance results.
• The Launcher provides a single point of access for all of the LoadRunner components.

LoadRunner Terminology

A scenario is a file that defines the events that occur during each testing session, based on performance requirements.

In the scenario, LoadRunner replaces human users with virtual users or Vusers. Vusers emulate the actions of human users working with your application. A scenario can contain tens, hundreds, or even thousands of Vusers.

The actions that a Vuser performs during the scenario are described in a Vuser script. To measure the performance of the server, you define transactions. A transaction represents end-user business processes that you are interested in measuring.

Load Testing Process

Load testing typically consists of five phases: planning, script creation, scenario definition, scenario execution, and results analysis.

Plan Load Test: Define your performance testing requirements, for example, number of concurrent users, typical business processes and required response times.

Create Vuser Scripts: Capture the end-user activities into automated scripts.

Define a Scenario: Use the LoadRunner Controller to set up the load test environment.

Run a Scenario: Drive, manage, and monitor the load test from the LoadRunner Controller.

Analyze the Results: Use LoadRunner Analysis to create graphs and reports, and evaluate the performance.

Conclusion:

Load Runner has good reporting features with which the user can easily analyze the performance test results.

Advantages Of Load Runner While Applying in Performace Testing

Any performance testing tool (or for that matter any other automation tool) should be used on a case-to-case basis, depending upon the requirements, client budget etc. Since the topic of our blog is limited to LoadRunner, I would like to present some advantages and disadvantages of using LoadRunner.

Advantages:

1. No need to install it on the server under test. It uses native monitors. For Ex: perfmon for windows or rstatd daemon for Unix
2. Uses ANSI C as the default programming language¹ and other languages like Java and VB.
3. Excellent monitoring and analysis interface where you can see reports in easy to understand colored charts and graphics.
4. Supports most of the protocols².
5. Makes correlation³ much easier. We will dig into correlation through a series of posts later.
6. Nice GUI generated script through a one click recording, of course you would need to modify the script according to your needs.
7. Excellent tutorials, exhaustive documentation and active tool support from HP.

Disadvantages:

The only disadvantage I can think is the prohibitive cost associated with the tool but that can also be compensated in the long run when you start getting a good ROI from the tool.

¹Programming/Scripting language is used to represent the captured protocol data and manipulate the data for play-back.

²Protocol is simply a language that your client uses to communicate with the system.

³Correlation is a way to substitute values in dynamic data to enable successful playback.

Software Testing Load Runner Interview Questions And Answers (45)

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 weather 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 7.2.

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* (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 than you can see database related issuesOverlay Graph: It overlay the content of two graphs that shares a common x-axis. Left Y-axis on the merged graph show’s 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 thethink 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:

The number of transactions per second

The number of pages per minute

The transaction response time that you want your scenario

The number of concurrent Vusers

The number of hits per second

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.