LOADRUNNER CONTROLLER:

Q. 1: What is the purpose of using HP - LoadRunner?

In real world scenario, it is not possible to create situation involving say one thousand users using a system simultaneously so as to test the behavior of the system under such stressful conditions. LoadRunner can create such a situation.

LoadRunner artificially simulates several thousand users - which are called Virtual Users. These artificial / digitally created users are simultaneously forced to operate on the same task, thereby loading the system in a way it is expected to be loaded by real human users in actual practice.

With LoadRunner we can simulate situation with hundreds or thousands of artificial users & we can impose definite, consistent and repeatable loads on the system thereby stressing it from end-to-end. This way we can emulate several business processes & production conditions, which a deployed application is going to encounter.

LoadRunner accurately measures, monitors, and analyzes a system’s performance and functionality.

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Q. 2: What are the essential capabilities we look in a typical application performance-testing Tool?

Essential capabilities of an application performance testing tool are that:

1) It must be able to test a system which combines many software applications and hardware platforms.

2) It must be able to determine the suitability of a server for any given application.

3) It must be able to test the server before the necessary client software has been developed.

4) It must be able to emulate an environment where multiple clients interact with a single server application.

5) It must be able to test an application under the load of tens, hundreds, or even thousands of potential users.

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Q. 3: What are the drawbacks of manual load testing processes?

Load testing of a complete system can be done manually by building an environment where many users work simultaneously on the system. Each user is made to work on his standalone machine and every individual submits input to the system. However due to complexity of such a system, following drawbacks are there

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1) Manual testing methods offer only a partial solution to the load testing.

2) Manual testing is expensive & requires large amounts of manpower & equipment.

3) Manual testing is complicated, especially while coordinating and synchronizing multiple testers.

4) Manual testing involves a high degree of organization, especially to record and analyze results meaningfully.

5)The repeatability of the manual tests is limited.

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Q. 4: How LoadRunner takes care of the shortcomings of manual performance testing?

1) LoadRunner reduces manpower requirements by replacing human users with virtual users or Vusers. These Vusers emulate the behavior of real users operating real applications.

2) Since several Vusers can run on a single computer, LoadRunner reduces the amount of hardware required for testing.

3) LoadRunner Controller allows us to easily and effectively control all the Vusers from a single point of control.

4) LoadRunner monitors the application performance online, enabling us to fine-tune the system during test execution.

5) LoadRunner automatically records the performance of the application during a test. We can choose from a wide variety of graphs and reports to view the performance data.

6) LoadRunner checks where performance delays occur: network or client delays, CPU performance, I/O delays, database locking, or other issues at the database server. LoadRunner monitors the network and server resources to help us improve performance.

7) Because LoadRunner tests are fully automated, we can easily repeat them as often as we need.

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Q. 5: What are the process elements of using LoadRunner?

Process elements of LoadRunner are :

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1) Scenario: Before using LoadRunner, we divide the application performance testing requirements into various scenarios. A scenario defines the events which occur during each testing session. Thus, for example, a scenario defines and controls the number of users to emulate, the actions that they perform, and the machines on which they run their emulations.

2) Vusers: In the scenario, LoadRunner replaces human users with virtual users or Vusers. When we run a scenario, Vusers emulate the actions of human users working with our application. While a workstation accommodates only a single human user, many Vusers can run concurrently on a single workstation. In fact, a scenario can contain tens, hundreds, or even thousands of Vusers.

3) Vuser Scripts: The actions that a Vuser performs during the scenario are described in a Vuser script. When we run a scenario, each Vuser executes a Vuser script. The Vuser scripts include functions that measure and record the performance of our application’s components.

4) Transactions: To measure the performance of the server, we define transactions. A transaction represents an action or a set of actions that we are interested in measuring. We define transactions within our Vuser script by enclosing the appropriate sections of the script with start and end transaction statements. For example, we can define a transaction that measures the time it takes for the server to process a request to view the balance of an account and for the information to be displayed at the ATM.

5) Rendezvous points: We 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, so that they may simultaneously perform a task. For example, to emulate peak load on the bank server, we can insert a rendezvous point instructing 100 Vusers to deposit cash into their accounts at the same time.

6) Controller: We use the LoadRunner Controller to manage and maintain our scenarios. Using the Controller, we control all the Vusers in a scenario from a single workstation.

7) Load Generator: When we execute a scenario, the Controller distributes each Vuser in the scenario to a load generator. The load generator is the machine that executes the Vuser script, enabling the Vuser to emulate the actions of a human user.

8) Performance analysis: Vuser scripts include functions that measure and record system performance during load-testing sessions. During a scenario run, we can monitor the network and server resources. Following a scenario run, we can view performance analysis data in reports and graphs.

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Q. 6: What are our expectations from a scenario load testing an application Server?

The scenario would define the following actions which would be required to be performed on the server during the load test.

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1) Emulating the conditions of controlled load on the server.

2) Emulating the conditions of maximum load on the server.

3) Measuring the server performance under load.

4) Check where performance delays occur: network or client delays, CPU performance, I/O delays, database locking, or other issues at the server.

5) Monitoring the network and server resources under load.

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Q. 7: What is the role of Remote Agent Dispatcher in LoadRunner?

The role of Remote Agent Dispatcher is to enable the Controller to start applications on the load generator.

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Q. 8: What is the role of LoadRunner Agent?

1) LoadRunner Agent enables the Controller and the load generator to communicate with each other.

2) When we run a scenario, the Controller instructs the Remote Agent Dispatcher to launch the LoadRunner agent.

3) The agent receives instructions from the Controller to initialize, run, pause, and stop Vusers.

4) The agent relays data on the status of the Vusers back to the Controller.

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Q. 9: What type of actions a Vuser can perform during database server testing?

A Vuser script can perform following actions while testing a database server:

1) Logging in to the Web application.

2) Connecting to the database server.

3) Submitting an SQL query.

4) Retrieving and processing the server response.

5) Disconnecting from the server and the Web.

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Q. 10: What are the broad steps involved in testing process by LoadRunner?

LoadRunner follows a Six–step process for testing the application under the load:

Step - 1: Planning the Test: Involves development of a thorough test plan for the success of the load testing effort.

Step - 2: Creating the Vuser Scripts: Vusers emulate human users interacting with our application. A Vuser script contains the actions which each Vuser performs during scenario execution.

Step - 3: 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. We can create scenarios using the Controller.

Step - 4: Running the Scenario: User load is emulated on the server by instructing multiple Vusers to perform tasks simultaneously. We can set the level of load by increasing and decreasing the number of Vusers that perform tasks at the same time.

Step - 5: Monitoring a Scenario: This can be done by executing scenario monitoring with the help of LoadRunner's set of many resources.

Step - 6: Analyzing Test Results: During scenario execution, LoadRunner records the performance of the application under different loads. We can use LoadRunner’s graphs and reports to analyze the application’s performance.

Q. 11: What are the benefits of a test plan for a successful load testing?

A well-defined test plan is the first essential step to successful testing.

Planning of load testing helps us in:

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1) Building test scenarios which accurately emulate our working environment. Load testing means testing our application under typical working conditions, and checking for system performance, reliability, capacity, and so forth.

2) Understanding as to which resources are required for testing. Application testing requires hardware, software, and human resources. Before we begin testing, we need to know which resources are available and decide how to use them effectively.

3) Defining success criteria in measurable terms. Focused testing goals and test criteria ensure successful testing. For example, it’s not enough to define vague objectives like "Check server response time under heavy load." A more focused success criterion would be "Check that 100 customers can check their account balance simultaneously, and that the server response time will not exceed one minute."

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Q. 12: What are the elements of Load Test Planning Process using LoadRunner?

Load test planning is a three-step process:

Step -1: Analyzing the Application: Involves becoming thoroughly familiar with the hardware and software components, the system configuration, and the typical usage model. This step ensures that the testing environment created by us will accurately reflect the environment and configuration of the application under test.

Step -2: Defining Testing Objectives: Before starting the testing process, we need to define exactly what we want to achieve.

Step -3: Planning LoadRunner Implementation: Involves decision making on how to use LoadRunner to achieve our testing goals.

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Q. 13: What factors do we consider while planning the system configuration before its load testing?

We describe the configuration of every system component like client machines, network, middleware, and servers in ample detail giving answers to the following:

1) How many users are anticipated to connect to the system?

2) What is the configuration of application client machine. Configuration includes information on hardware, memory, operating system, software, development tool etc.?

3) What types of database and Web servers are used with the information of hardware, database type, operating system, file server etc.?

4) How does the server communicate with the application client?

5) What is the middleware configuration and application server between the front-end client and back-end server?

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6) What other network components are used like modems etc. which may affect response time?

7) What is the throughput of the communications devices & How many concurrent users can each device handle?

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Q. 14: What factors do we consider regarding system usage while planning the load testing?

1) Consideration as to how the system is typically used, and decide which functions are important to test.

2) Consideration as to who uses the system, what are the number of each type of user and what are the common tasks performed by each user.

3) Consideration of any background load which might affect the system response time.

For example, say 500 persons log on to the accounting system every morning, and the same office network has a constant background load of 100 users performing various word processing and printing tasks. We would create a LoadRunner scenario with 600 virtual users signing in to the accounting database, and check the server response time.

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Q. 15: What are the broad objectives before planning load testing?

Before starting testing, we need to define our objectives precisely as to what we want to achieve.

Broad application testing objectives for load testing with LoadRunner can be:

1) Measuring end-user response time: To know how long does it take to complete a business process?

2) Defining optimal hardware configuration: To know which hardware configuration provides the best performance?

3) Checking reliability: To know how hard or long can the system work without errors or failures?

4) Checking hardware or software upgrades: To know how does the upgrade affect performance or reliability?

5) Evaluating new products: To know which server hardware or software should we choose?

6) Measuring system capacity: To know how much load can the system handle without significant performance degradation?

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7) Identifying problem areas: To know which element is slowing down the response time?

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Q. 16: Load Testing is applicable during which stages of product life cycle?

Load testing is necessary throughout the product life cycle.

Load Testing activities performed during various stages of product life cycle are:

1) During Planning and Design stage: Evaluation of new products & measurement of response time of every activity.

2) During Product Development stage: Measurement of response time of every activity, checking of optimum hardware configuration, checking of hardware and software upgrades and checking of reliability.

3) During Product Deployment stage: Checking of reliability, measurement of response time of every activity and measurement of system capacity.

4) During Production stage: Measurement of response time of every activity and Identification of various problem areas.

5) During Evolution stage: Checking of hardware and software upgrades and measurement of system capacity.

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Q. 17: At which points we use LoadRunner to measure the response time in our application?

Following type of response times are measured to decide as to where to run the Vusers and which Vusers to run, according to our predefined test objectives:

1) Measurement of end-to-end response time: We can measure the response time which a user experiences by running a GUI Vuser at the front end. GUI Vusers emulate real users by submitting input to and receiving output from the client application.

We can run GUI Vusers at the front end to measure the response time across the entire network, including a terminal emulator or GUI front end, network, and server.

2) Measurement of network and server response times: We can measure network and server response time, excluding response time of the GUI front end, by running Vusers on the client machine. Vusers emulate client calls to the server without the user interface. When we run many Vusers from the client machine, we can measure how the load affects network and server response time.

3) Measurement of GUI response time: We can find out as to how the client application interface affects response time by calculating the difference among the previous two measurements i.e.

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GUI response time = (End-to-end response time) - (Network and server response time)

4) Measurement of server response time: We can measure the time it takes for the server to respond to a request without going across the network. When we run Vusers on a machine directly connected to the server, we can measure the server performance.

5) Measurement of middleware-to-server response time: We can measure response time from the server to middleware if we have access to the middleware and its API. We can create Vusers with the middleware API and measure the middleware-server performance.

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Q. 18: What are the broad basis for creating Vuser scripts?

Since Vusers emulate the actions of a typical enduser, the Vuser scripts are created with a consideration of end-user tasks.

Vuser scripts are created based on the following:

1) Analysis of Vuser types: For finding out the number and type of Vusers expected to be created.

2) Activities expected to be performed by the Vusers: For example, for load testing a banking application, we would create a Vuser script which performs typical banking related activities.

3) Test objectives: Form the basis of taking decision on tasks to be measured and defining their transactions.

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Q. 19: What factors do we consider while selecting hardware for using LoadRunner?

For running the desired number of Vusers the hardware and Operating system must be adequately powerful and fast.

Following factors are given due consideration while deciding the number of machines and their configuration:

1) Make a provision of running LoadRunner Controller on a separate machine.

2) Make a provision of a separate Windows-based machine for every GUI Vuser. However one UNIX machine can take care of running of several GUI Vusers.

3) Keep the configuration of GUI Vusers testing machine same like the actual user’s machine.

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Q. 20: How LoadRunner can be helpful in checking the reliability of a hardware system?

LoadRunner can provide good pointers to decision making in following areas pertaining to hardware:

1) Finding out the level of system stability under heavy or continuous work loads, by creating stress on the system.

2) Testing the system by forcing it to handle the extended activity in a compressed time period to simulate the kind of activity a system would normally experience over a period of weeks or months.

Q. 21: How do we measure the system capacity?

We measure system capacity to find out how much excess capacity the system can handle without any degradation in its performance .

For checking the capacity of a system, we compare the performance versus load on the existing system, and find out a point at which significant degradation of response-time starts taking place. Point is known as "knee" when plotted over a response time curve.

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Q. 22: What is the purpose of creating Scenarios in LoadRunner?

For testing a system by using LoadRunner, we need to create a scenario. Scenario is a file containing complete information about the testing session. The scenario is a means of emulating a real-life user.

The scenario contains following information about the mechanism of emulating the real users:

1) Details of groups of virtual users or Vusers.

2) Details of test scripts the Vusers will run.

3) Details of load generators upon which the scripts shall be made to run.

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Q. 23: How many types of scenarios can be created while using Controller of LoadRunner?

We can create any one type of scenario out of the following:

1) Manual Scenario: Scenario is created manually by defining the number of Vuser groups we want to run, and building a schedule for LoadRunner to run these groups. Manual scenario can be created by defining the total number of Vusers to be used in the scenario, or assigning a percentage of the total number of Vusers to each script.

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2) Goal-Oriented Scenario: We define the goals that we want to achieve in our test and LoadRunner automatically builds a scenario for us, based upon our goals.

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Q. 24: How can we change the maximum number of scripts displayed in the Available Scripts list?

We can change the maximum number of scripts displayed in the Available Scripts list by modifying the registry key:

HKEY_CURRENT_USER\Software\Mercury Interactive\RecentScripts\max_num_of_scripts

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Q. 25: What is the purpose of Scenario Files?

A scenario provides detailed description of various events taking place during every load testing session.

A scenario is created by using the Design view of Controller in LoadRunner. Once a scenario is created, LoadRunner saves the information in a

scenario file having an extension (*.lrs).

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Q. 26: What methods are available in LoadRunner for building scenarios?

Two methods are available through which we can create scenarios.

1) Manual Scenario creation method: Involves creating groups and specifying the script, the load generator, and the number of Vusers included in each group. We can chose to opt for using Percentage Mode to distribute our Vusers among various scripts.

2) Goal Oriented Scenario creation method: Involves defining the goals we want our test to achieve, and LoadRunner automatically builds a scenario for us, based on these goals.

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Q. 27: How can we change the maximum number of scripts displayed in the Available Scripts list?

We can change the maximum number of scripts displayed in the Available Scripts list by modifying the registry key:

HKEY_CURRENT_USER\Software\Mercury Interactive\RecentScripts\max_num_of_scripts

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Q. 28: What is the purpose of having Vuser groups in scenarios?

A scenario consists of groups of Vusers which simulate the actions of human users on the application under test. When a particular scenario is run, the Vusers generate load on the server, and LoadRunner monitors the server and transaction performance..

Vuser groups are created to organize several Vusers in a scenario into manageable groups. Vuser groups are created by including Vusers having similar characteristics. For example, when many Vusers run the same Vuser script, we can club them into one Vuser group.

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Q. 29: What type of actions can be performed on a Vuser group or scenario?

Following actions can be performed on a Vuser group:

1) Defining the group name, Vuser quantity, load generators, and scripts for the Vuser group.

2) Adding load generators to the Vuser group and configuring the load generators.

3) Adding and configuring scripts to the Vuser group.

4) Enabling or disabling a Vuser group for the scenario.

5) Removing a Vuser group from the scenario.

6) Scheduling the Vuser group execution.

7) Defining service level agreements for the scenario.

8) Running, stopping & resetting the scenario.

9) Configuring the settings of scenario results.

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Q. 30: What is the meaning of pending status for a Vuser?

Pending status for a V user indicates that the Vuser is ready to be initialized and is waiting for an available load generator, or is transferring files to the load generator. The Vuser will run when the conditions set in its scheduling attributes are met.

Q. 31: What is the meaning of rendezvous status for a Vuser?

Rendezvous status for a Vuser indicates that the Vuser has arrived at the rendezvous and is waiting to be released by LoadRunner.

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Q. 32: What is the purpose of Gradual Stop option for the Vusers?

Gradual Stop option Instructs the Controller to complete the current iteration or action before stopping the Vuser. This option is only available when the Vuser is in the RUN state.

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Q. 33: How do we modify the run-time settings of multiple scripts?

We need to chose the method of modifying the run-time settings:

1) Modification method for Shared run-time settings: This method opens one window containing all of the run-time settings in blank mode. In this mode, we set only the options that we want to modify for all selected scripts. All other run-time settings remain unchanged.

Some of the run-time settings cannot be modified in shared mode. These settings do not appear. To modify them, we need to open the run-time settings for each individual script.

2) Modification method for Individual run-time settings: This method opens a separate window for each selected script. In this mode, we modify each script’s settings individually.

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Q. 34: What configuration settings we can define for Load Generators in a scenario?

With the help of Load Generators dialog box, we can set following type of load generator’s attributes:

1) Defining which load generators will run Vusers in the scenario. For example, if a load generator is unavailable for a particular scenario run, we can exclude it temporarily instead of removing it entirely from your list of load generators.

2) Selecting which load generators will take part in the scenario by using the Enable and Disable commands. Disabling a load generator temporarily removes it from the list. Enabling a load generator reinstates it.

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Q. 35: What is the role of controller in LoadRunner?

The Controller monitors a Windows load generator’s CPU usage and automatically stops loading Vusers on a load generator when it becomes overloaded.

We can monitor the status of a machine’s CPU usage. When the CPU usage of a load generator becomes problematic, the icon to the left of the load generator name contains a yellow bar. When the machine becomes overloaded, the icon contains a red bar.

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Q. 36: What are the Terminal Services in LoadRunner?

Terminal services allows centralized management of computing resources for each client connected to the server, and provides each user with their own working environment.

We use LoadRunner’s Terminal Services Manager to remotely manage multiple load generators running in our load testing scenario on a terminal server. With the help of Terminal Services Manager, we can select the number of terminals to be used in our scenario & the maximum number of Vusers which can be run per terminal. The Terminal Services Manager then evenly distributes the number of virtual users among the client sessions.

With the help of Terminal Server Client, we can operate in a server-based computing environment from a remote machine. The terminal server transmits applications over the network and displays them via terminal emulation software. Every user logs on and sees only his individual session, which is managed transparently by the server operating system, independent of any other client session.

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Q. 37: What is the use of Creating a Manual Scenario Using the Percentage Mode?

A manual scenario is created in the Percentage mode by defining the total number of Vusers to be used in the scenario, and assigning load generators and a percentage of the total number of Vusers to each script.

While creating a new scenario, we can access the Percentage Mode directly by selecting the "Use the Percentage Mode to distribute the Vusers among the scripts" in the New Scenario dialog box.

A scenario created in the Vuser Group Mode can be easily converted to the Percentage Mode.

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Q. 38: What are the key considerations while converting a scenario from Vuser Group Mode to Percentage Mode?

1) In case we have defined multiple scripts for a Vuser group, the number of Vuser scripts created in the Percentage Mode will be same as the number of scripts defined for the group.

2) All Load Generators will be assigned to all Vuser scripts created in the Percentage Mode. In case we have defined multiple load generators for a Vuser group, the Vusers we assign to the scripts in the Percentage Mode will be distributed evenly among the load generators previously assigned by us to the group.

3) All Vuser group schedule settings will be lost. All profiles will contain scenario schedule settings only.

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Q. 39: What are the key considerations while converting a scenario from Percentage Mode to Vuser Group Mode?

1) Each script will be converted to a Vuser group.

2) In case we have defined multiple load generators for a Vuser script, the Vuser group which is created when converting the scenario will also contain multiple load generators.

3) All schedule settings will be retained as it is.

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Q. 40: What is the purpose of Scheduling Scenarios?

After creating a scenario, we schedule it to start running at a specified time. We can make a schedule defining the time at which to initialize, start, and stop Vusers during the scenario run, and how long an action should continue running.

We can restrict the execution duration of the scenario or of a Vuser group within the scenario. We can also stipulate how many Vusers to start and stop running within a certain time frame. We can specify whether LoadRunner should start or stop running all Vusers in a scenario simultaneously, or only a certain number of Vusers within a specified amount of time.

Q. 41: What is the effect of Rendezvous points on the running of scenarios as per schedule?

Rendezvous points, if present in a script, interfere with the scheduled scenario run. The scenario will not run as scheduled due to the presence of rendezvous points in the script.

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Q. 42: What are the methods by which we can schedule the enabled Vuser groups in a scenario?

After creating a scenario, we can schedule the enabled Vuser groups to run according to either of the following:

1) As a part of a whole scenario: When we run a scenario, LoadRunner runs all the Vuser groups enabled in the scenario. The schedule defined for running the scenario is applied to all the Vuser groups concurrently, and LoadRunner applies each action proportionately to all the Vusers groups.

2) As per its own schedule: For each enabled Vuser group in a scenario, we can design a separate execution schedule. We can specify when to start running the Vuser group, how many Vusers to start and stop running within given time intervals, and how long the Vuser group should continue running.

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Q. 43: How many modes are available to us for scheduling the running of scenario?

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We can schedule a scenario to run in one of the following modes:

1) Real-life schedule: The scenario runs according to a user-defined group of actions that simulate a real-life schedule of events. Vuser groups run according to the iterations defined in their run-time settings, but we can define how many Vusers to run at a time, how long Vusers should continue to run, and how many Vusers to stop running at a time.

2) Classic Schedule: All enabled Vuser groups run together on one schedule, each according to its own run-time settings. We can schedule how many Vusers to start running at a time, how long to run the Vusers, and how many Vusers to stop running at a time.

3) Run until complete: All the Vuser groups in the scenario run according to the iterations defined in their run-time settings. Each Vuser group in the scenario runs its defined course, and when all the Vuser groups have finished running, the scenario run is complete.

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Q. 44: What is the purpose of specifying Service Level Agreements in scenarios?

While creating a load testing scenario, we can specify our goals or service level agreements - SLA's for the performance measurement.

When this scenario is made to run the LoadRunner captures all the performance related data. During analysis phase, Analysis compares this data against the SLAs and determines SLA status for the defined measurements.

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Q. 45: What methods LoadRunner uses to find out the SLA status?

Depending on the measurements being evaluated by us, LoadRunner finds out the SLA status in one of the following ways:

1) As per time interval within the run: Analysis displays SLA statuses at set time intervals in the timeline. For example, every 10 seconds - Analysis checks to see if the measurement’s performance has deviated from the threshold defined in the SLA.

2) As per the whole run: Analysis displays a single SLA status for the whole scenario run. The measurements include - Total Hits, Average Hits, Total Throughput, and Average Throughput.

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Q. 46: How many types of Goal Oriented Scenarios can be created in LoadRunner?

In a goal-oriented scenario, we define the goals required to be achieved through our tests, and LoadRunner automatically builds a scenario for us based on these goals.

When we want to test how many Vusers the application can run simultaneously, it is better to define a type of goal for the Virtual Users.

Following five types of goals can be defined in a goal-oriented scenario:

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1) Defined number of virtual users

2) Defined number of hits per second by the Web Vusers.

3) Defined number of transactions per second.

4) Defined number of pages per minute by the Web Vusers.

5) Defined transaction response time we want our scenario to reach.

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Q. 47: Under what circumstances a Pages per Minute or Hits per Second goal-oriented scenario fails?

Pages per Minute or Hits per Second goal-oriented scenario is assigned a "Failed" status in situations like:

1) When the Controller has twice attempted to reach the goal using the maximum number of Vusers specified, and the goal could not be reached.

2) When no pages per minute or hits or transactions per second were registered after the first batch of Vusers was run.

3) When the number of pages per minute or hits or transactions per second did not increase after the Controller ran a certain number of Vuser batches.

4) When all the Vusers that were run failed.

5) When there were no available load generators for the type of Vusers we attempted to run.

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Q. 48: What is Load Balancing process in LoadRunner?

Load balancing is the process, which evenly distributes the load generated by Vusers among the requested load generators, thereby ensuring an accurate load test.

When a Windows load generator’s CPU usage becomes overloaded, the Controller stops loading Vusers on the overloaded load generator, and automatically distributes them among load generators taking part in the scenario.

Load balancing option is available only in goal-oriented scenarios and manually controlled scenarios in the Percentage Mode.

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Q. 49: What policy attributes can be defined for rendezvous points?

Setting the rendezvous policy determines how the Vusers handle a rendezvous point. We can set the following policy attributes for every rendezvous point:

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1) Release policy: Defines how many Vusers will be released from a rendezvous point at a time.

2) Timeout policy: Defines how long the Controller shall wait before releasing Vusers from a rendezvous point.

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Q. 50: Can we disable a particular Vusers at Rendezvous Points?

We can disable a rendezvous point for all Vusers in a scenario.

In addition to this we can disable a rendezvous point for a particular Vusers.

By disabling Vusers at a rendezvous point, we temporarily exclude them from participating in the rendezvous. Enabling disabled Vusers returns them back to the rendezvous.

Q. 51: What type of status related Rendezvous Information is available to us during creation of a scenario?

Following Rendezvous Information is available to us for viewing & necessary modifications:

1) Current Status: The number of Vusers that arrived at the rendezvous point out of the total number of Vusers assigned to the rendezvous.

2) Time: The time at which the Vusers at the rendezvous point were released.

3) Reason: The reason the Vusers at the rendezvous point were released. The possible reasons are Timeout or Arrived.

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Q. 52: Out of Individual Load Generator settings & Global Settings, which ones come into effect?

When the global scenario settings differ from those of an individual load generator, the load generator settings override them.

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Q. 53: What is the use of LoadRunner Expert mode?

We can configure additional settings for the LoadRunner agent and other LoadRunner components with the help of LoadRunner Expert mode.

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Q. 54: How LoadRunner takes care of timeout value requirements in case of large number of Vusers?

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LoadRunner automatically understands the fact that the number of active Vusers has a significant effect on the timeout values.

For example, 1000 Vusers trying to initialize will take much longer than 10 Vusers. Taking care of this, LoadRunner automatically adds an internal value, based on the number of active Vusers, to the timeout value specified by us.

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Q. 55: While running a scenario, the run-time files are stored at which location by default?

While we run a scenario, by default the run-time files get stored locally on each load generator machine running the Vuser script.

The default location of the files is under the temporary directory specified by the load generator’s environment variables like Windows - TEMP or TMP Directory.

If no environment variable is defined, the files get saved to the /tmp directory.

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Q. 56: What are the various types of Primary Run-time files?

Primary run-time files are of following types:

1) Vuser Script files: When we run a Vuser, the Controller sends a copy of the associated Vuser script to the Vuser load generator. These script files are stored in the load generator’s temporary run-time directory.

2) Result files: While we run a scenario, the participating Vusers write their results to the temporary run-time file directory. After scenario execution, these result files are consolidated and the results from all the load generators are transferred to the results directory.

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Q. 57: How transfer of script files takes place at run time in case Vusers access the scripts at some shared location?

If we specify that all Vusers access their Vuser scripts directly at some shared location, no transfer of script files take place at run time.

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Q. 58: What is Path translation in LoadRunner

Path translation is a mechanism used by LoadRunner to convert remote path names. We need to do path translation, when we specify a shared network drive for run-time file storage.

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Q. 59: What preparatory steps are recommended for running a scenario?

Before running a scenario following are suggested steps:

1) Specify the location of the results.

2) Assign a name to the results.

3) Scheduling of the scenario.

4) Providing scenario summary information.

5) Specification of applications to be invoked at the start of the scenario.

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Q. 60: What is the extension of scenario result file?

The general information about the scenario are stored in a result file with an extension (.eve and .lrr)

Q. 61: How Analysis module of LoadRunner interacts with the results files?

When analysis graphs and reports are generated, the Analysis module of LoadRunner copies all the scenario result files to a database.

Then the Analysis module directly interacts with the database and does not require the individual result files.

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Q. 62: What are the benefits of saving scenarios in a Quality Center Project?

When Controller module of LoadRunner is connected to a Quality Center project, we can create a new scenario in the Controller and save it directly to the Quality Center project.

This helps us in keeping a track of all scenarios created for each subject and allows monitoring the progress of test planning and creation.

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Q. 63: How can we test the functionality of an application under heavy load using LoadRunner?

LoadRunner integrates functional testing scripts created by Functional testing Tools like QTP or WinRunner. These scripts in the form of GUI Vuser scripts integrate into the scenarios of LoadRunner.

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Q. 64: What are the benefits of running functional test scripts in LoadRunner?

1) To see how the functionality of the application gets affected under the heavy load.

2) To measure the end-to-end response time experienced by a typical user on the client side while the application is under load.

3) By including QTP test scripts at specific points in a LoadRunner scenario we can confirm that the functionality of our application does not get affected by the extra load at these sensitive points.

4) When a GUI Vuser script runs on our screen during the LoadRunner scenario, we can watch the actual steps executed by the Vuser in a real time.

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Q. 65: What is a GUI Vuser?

A GUI Vuser emulates the complete environment of a human user. GUI Vusers enable us to measure and monitor end-to-end user response times while our client/server system is under load.

A GUI Vuser can be programmed to read and act on information that appears on its machine’s display. All actions of every GUI Vuser are described in a GUI Vuser script generally created in QTP or WinRunner.

GUI Vusers are monitored and managed through the Controller module of LoadRunner.

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Q. 66: Can we use VuGen module of LoadRunner to run a GUI Vuser script?

We cannot use VuGen to run a GUI Vuser script.

We use the Controller module of LoadRunner to run a GUI Vuser script as part of a scenario. Whereas we use QTP or WinRunner to run a GUI Vuser script in the standalone mode.

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Q. 67: What is End-to-end response time in relation to GUI Vuser Technology?

End-to-end response time means the total time that a user waits for a response after submitting a request. GUI Vusers measure real end-to-end response times. End-to-end response times include GUI response times plus network and server response times.

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Q. 68: What are the special design constraints with QTP Tests while adopting in LoadRunner?

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1) Only simple QTP tests should be adopted for use in LoadRunner & should be designed to pinpoint specific operations.

2) LoadRunner cannot run nested action iterations.

3) Do not include references to external actions or other external resources, like an external Data Table file, environment variable file, shared object repositories etc.

4) Include transactions in QTP test since LoadRunner only provides performance information for data that is included within a transaction.

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Q. 69: How do we define transactions within our Vuser script?

Transactions are defined as an action or a set of desired actions to measure the performance of a server.

We define transactions within our Vuser script by enclosing the appropriate sections of the script with start and end transaction statements. For example, we can define a transaction, which measures the time it takes for the server to process a request to view the balance of an account and for the information to be displayed at the ATM.

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Q. 70: For use in LoadRunner, which statements are manually added to basic Vuser script recorded in WinRunner?

Since LoadRunner provides performance-related information only for the data included within a transaction. Hence WinRunner test scripts are manually edited to include transactions needed to be used by LoadRunner. Thus following statements are manually inserted into WinRunner test scripts :

1) Transaction statements to measure the performance of the server.

2) Rendezvous statements to emulate a specific user load.

Q. 71: What are the special considerations while running the LoadRunner scenario integrated with GUI Vuser script created in QTP or WinRunner?

1) Run just the one GUI Vuser concurrently per machine.

2) Ensure that QTP and WinRunner are closed before running the scenario.

3) In the Run-time Settings for script dialog box, only the General categories and sub-categories like General, Iterations, Miscellaneous, Think Time etc. are relevant for QTP and WinRunner tests.

4) The Replay options are not relevant for QTP and WinRunner tests.

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Q. 72: What actions are performed by the LoadRunner during scenario execution?

While executing a scenario, the LoadRunner does the following:

1) Recording of the duration of the transactions you defined in the Vuser scripts

2) Performing the rendezvous included in the Vuser scripts

3) Collecting error, warning, and notification messages generated by the Vusers

During running of scenarios Controller module of LoadRunner performs following actions:

a) Checking the scenario configuration information.

b) Invokes the applications selected by us for running with the scenario.

c) Distributing each Vuser script to its specified load generator. When the Vuser groups become re ready, they start executing their respective scripts.

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Q. 73: Can we activate an additional Vuser while a scenario is running?

With the help of Run / Stop Vusers dialog box, we can activate an additional Vuser while a scenario is running.

The scenario will finally end when all the Vusers have completed their scripts, or when the specified duration finishes out, or when we terminate it.

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Q. 74: What are the brief steps of running a scenario?

Scenario execution by & large follows following basic steps:

Step -1:Opening of an existing scenario or creating a fresh one.

Step -2:Configuring and scheduling the scenario.

Step -3:Setting the results directory.

Step -4:Running and monitoring the scenario.

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Q. 75: How running of individual Vusers differ from running an entire scenario?

We can run all the Vusers and Vuser groups all together in a scenario, alternatively we can chose the specific Vuser groups and Vusers and can run them individually.

The difference in operation lies as under:

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1) When We run an entire scenario, LoadRunner does not begin running Vusers until they all reach the Ready state.

2) When we run individual groups or Vusers, LoadRunner runs each Vuser immediately after it reaches the Ready state.

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Q. 76: What do we mean by initialization of Vusers in a group?

By initializing the Vusers, we distribute the Vusers in the group to their specified load generators so that they get ready to execute their script.

The status of the Vuser group changes from Down to Pending to Initializing to Ready. In case a particular Vuser group does not get initialized due to any reason, the status of this Vuser group changes to Error.

By initializing all the Vusers in a group before running them, we can ensure that they all begin executing the scenario at the same time.

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Q. 77: How the addition of new Vusers differ among various modes of running a scenario?

We run a scenario or Vuser in two modes like: 1) Vuser Group Mode 2) Percentage Mode.

1) Vuser Group Mode: Here we control the number of new Vusers that can be added to each Vuser Group, and the load generators on which these additional Vusers will run.

2) Percentage Mode: Here we control the number of new Vusers that can be distributed among the Vuser scripts according to the percentage you define, and the load generators on which these additional Vusers will run.

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Q. 78: What type of Vuser activity can be seen while a scenario is running?

LoadRunner allows us to see the following Vuser activity during a scenario run:

1) On the Controller load generators, we can view the Output window, monitor Vuser performance online, and check the status of Vusers executing the scenario.

2) On remote machines, we can view the Agent summary with information about the active Vusers.

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Q. 79: How connections are established among Controller & Load Generators under fire walled environment?

In a conventional non-firewalled load test scenario, the Controller can directly connect to the LoadRunner agents running on remote machines.

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While running Vusers over a firewall, the direct connection between the controller and the Load Generator gets blocked by the firewall. The reason being that the Controller does not have permissions to open the firewall.

LoadRunner addresses this problem by using a communication configuration based on HTTPS or secured TCP/IP.

In such a fire walled environment, a LoadRunner agent is installed on load generators running Vusers, and on Monitor machines which monitor the servers. This agent communicates through port 443 in the firewall.

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Q. 80: What is a MI Listener machine?

The MI Listener machine works as a router between the following:

1) The agent on the load generator machine and the Controller, enabling the Controller to run Vusers over a firewall.

2) The agent on the Monitor over Firewall machine and the Controller, enabling the Controller to monitor the servers that are located over a firewall.

MI Listener components are installed on a dedicated machine.

Q. 81: How the communication takes place across MI Listener machine in a fire-walled environment?

The MI Listener serves the purpose of a router between the Controller and the LoadRunner agent.

When the LoadRunner agent connects to the MI Listener machine, the MI Listener keeps a listing of the connection to the agent using a symbolic name that the agent passed to it.

When the Controller connects to the MI Listener machine, it communicates to the MI Listener through port 50500.

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Q. 82: How many types of online monitors are available for controller machines?

1) Run-Time Monitors: For displaying the number and status of Vusers participating in the scenario, as well as the number and types of errors that the Vusers generate.

2) Transaction Monitors: For displaying the transaction rate and response time during scenario execution.

3) Web Resource Monitors: For providing information about the number of Web connections, throughput volume, HTTP responses, server retries, and pages downloaded to the Web servers during the scenario.

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4) System Resource Monitors: For measuring the Windows, UNIX, Tuxedo, SNMP, Antara FlameThrower, and SiteScope resources used during a scenario.

5) Network Delay Monitor: For displaying the information about the network delays on our system.

6) Firewall Monitor: For measuring the statistics of the firewall servers during the scenario.

7) Web Server Resource Monitors: For measuring the statistics of the Apache, Microsoft IIS, iPlanet Web servers during the scenario.

8) Web Application Server Resource Monitors: For measuring the statistics of the Ariba, ATG Dynamo, BroadVision, ColdFusion, Fujitsu INTERSTAGE, iPlanet, Microsoft ASP, Oracle9iAS HTTP, SilverStream, WebLogic and WebSphere application servers during the scenario.

9) Database Server Resource Monitors: For measuring the statistics of the SQL server, Oracle, Sybase, and DB2 databases during the scenario.

10) Streaming Media Monitors: For measuring the statistics of the Windows Media Server and RealPlayer audio/video servers, as well as the RealPlayer and Media Player client during the scenario.

11) ERP/CRM Server Resource Monitors: For measuring the statistics of the SAP Portals, Siebel Servers, and PeopleSoft servers during the scenario.

12) Java Performance Monitor: For measuring the statistics of Java Platforms and Java-based applications using J2EE machines.

13) J2EE & .NET Diagnostics Monitors: For providing information to trace, time, and troubleshoot individual transactions through J2EE & .NET Web, application, and database servers.

14) Application Component Monitor: For measuring the statistics of the Microsoft COM+ server during a scenario run.

15) Application Deployment Solutions Monitor: For measuring the statistics of the Citrix MetaFrame servers during a scenario run.

16) Middleware Performance Monitors: For measuring the statistics of the Tuxedo and IBM Web servers during a scenario run.

17) Infrastructure Resources Monitor: For measuring the statistics of the network client data points during a scenario run.

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Q. 83: What is Merging Graphs in LoadRunner?

LoadRunner allows us to merge the results of two graphs from the same scenario into a single graph.

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The merging helps us to compare several different measurements at once. For example, we can make a merged graph to display the Web Throughput and Hits per Second, as a function of the elapsed time.

To merge two graphs, the x-axis of both the graphs must be the same measurement.

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Q. 84: What situations are best suited for performing path translation?

1) When saving run-time result files to a shared drive which has been mapped differently by the Controller and remote load generator.

2) When the remote machine maps the path as another drive letter or path, path translation is necessary to enable the load generator to recognize the script location.

2) Across platforms - to translate Windows-based paths as seen by the Controller into paths recognized by the UNIX Vuser load generator.

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Q. 85: What is the use of Expert mode of Controller module of LoadRunner?

It is basically meant for the support personnel & helps us in getting access to the system information.

When we work in the Expert mode, the Controller dialog boxes contains additional options for fine tuning the Controller operation.

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Q. 86: How to check whether a particular problem lies with a scenario or lies with the Vuser script?

1) Verify that the script runs properly on all remote load generators in stand-alone mode.

2) Test the GUI Vuser scripts on Windows platforms using WinRunner.

3) Test the Vuser scripts on UNIX platforms by running them from the command line.

4) Test all other types of Vuser scripts on Windows platforms by running them from VuGen, or by running a single user from the Controller.

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Q. 87: What to do when a test passes when run in VuGen, but fails when run in Controller?

When a test runs in VuGen, the full browser is used. However when this test is run in Controller, it use the browser basics only.

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Hence before running a scenario in the Controller with multiple Vusers, it is a best practice to run a single Vuser in stand-alone mode to ensure that the test is free from bugs.

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Q. 88: What to do when Controller machine fails to connect to the remote load generator machine?

Check the following items:1) Check TCP/IP connectivity: Ensure full TCP/IP connectivity among the Controller and Vuser machines. Use the ping utility from the DOS command line to verify communication with a remote machine.

2) Check Load generator connections: Ensure full connectivity of the load generator with every remote load generators from the Controller’s Load Generators dialog box.

3) Check UNIX shell: For UNIX Vusers, make sure that the Windows Controller can execute a remote shell command.

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Q. 89: What is the use of LoadRunner Agent?

LoadRunner Agent runs on the load generators and enables communication between the Controller, load generators, and MI Listeners under fire-walled environment.

The LoadRunner agent receives instructions from the Controller to initialize, run, pause, and stop Vusers. At the same time, the agent also relays data on the status of the Vusers back to the Controller.

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Q. 90: How can we increase the load during the Load test?

We can increase the load on the application during a running load test by manually adding more Vusers.

Q. 91: What to do in case of a warning message that Controller cannot activate additional Vusers?

This is a hardware related problem. It happens when we use our local machine having limited memory resources, as a load generator.

Hence it is better to use a dedicated machine as a load generator to avoid such problems.

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Q. 92: How to know as to whether my application performed well under the load?

Look at the transaction response time and find out whether the transaction was within an acceptable limit for the customer.

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If the transaction response time degrades, we need to look for problems.

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Q. 93: When do we use of goal-oriented scenario in LoadRunner?

Prior to deploying an application, we want to run an acceptance test to make sure that the system will withstand the real-life expected workload.

We have an idea about a rate at which we expect the server should perform say in terms of number of hits or transactions per second.

Using a goal-oriented scenario we define a goal for the number of hits per second, transactions per second, or the transaction response time which we want to generate.

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Q. 94: How many types of goals are provided by LoadRunner in a goal oriented scenario?

LoadRunner provides following five types of goals in a goal oriented scenario:

1) Number of concurrent Vusers.

2) Number of hits per second.

3) Number of transactions per second.

4) Number of pages per minute.

5) Transaction response time which we want the scenario to reach.

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Q. 95: What is the objective of an analysis session after the load test?

The aim of an analysis session is to find out the failures in performance of our system and then to point out the root cause of such failures.

Following questions are asked during the analysis session.

1) Were the test expectations met?

2) What was the transaction response time on the user’s end under load?

3) Did the SLA meet or deviate from its goals?

4) What was the average transaction response time of the transactions?

5) What parts of the system could have contributed to the decline in performance?

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6) What was the response time of the network and servers?

7) Can we find a possible cause by correlating the transaction times and backend monitor matrix?

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Q. 96: What to do when a script fails during simple playback, while during recording same actions were successful?

Many applications use dynamic values which change every time we use the application. For example, some servers assign a unique session ID for every new session. When we try to replay a recorded session, the application creates a new session ID which happen to differ from the recorded session ID.

LoadRunner addresses this issue through correlation. Correlation saves the changing values, in this case the session ID, to a parameter. When running the emulation, the Vuser does not use the recorded value and instead of it, it uses the new session ID, assigned to it by the server.

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Q. 97: How to confirm as to whether the desired content is the same as the returned web page?

This can be done through the content check which verifies that the expected information appears on a Web page while the script is running.

We can insert following two types of content checks:

1) Text check: For checking that a text string appears on a Web page.

2) Image check: For checking an image on a Web page.

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Q. 98: What is the use of a Throughput graph?

The Throughput graph shows the amount of data in terms of bytes which the Vusers receive from the server at any given second.

We then compare this graph with the Transaction Response Time graph to see how throughput affects transaction performance.

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Q. 99: How to know that the test has finished running?

When the test finishes its run, the Scenario Status pane shows the Down status. This indicates that the Vusers have stopped running.

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We can look in the Vuser dialog box to see the status of each individual Vuser.

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Q. 100: How can we instruct LoadRunner to randomly run only one Vuser in a group?

This can be done by right-clicking the Vuser group and selecting "Run One Vuser Until Complete".

A Vuser script log will open, displaying the run-time information about the Vuser.

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