Load Runner

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 LoadRunnerâ€â"¢s graphs and reports to analyze the applicationâ€â"¢s performance.

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.

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.

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.

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.

 

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

How do you write user defined functions in LR? Give me few functions you wrote in your previous project? –

Before we create the User Defined functions we need to create the external
library (DLL) with the function. We add this library to VuGen bin directory. Once the library is added then we assign user defined function as a parameter. The function should have the following format: __declspec (dllexport) char* <function name>(char*, char*)Examples of user defined functions are as follows:GetVersion, GetCurrentTime, GetPltform are some of the user defined functions used in my earlier project.

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.

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.

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.

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'

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.

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 â€Å"Continue on error” option in Run-Time Settings.  

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.

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.

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.

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.

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.

How did you find database related issues? –

By running â€Å"Database” monitor and help of â€Å"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 issues

What is the difference between Overlay graph and Correlate graph? –

Overlay Graph: It overlay the content of two graphs that shares a common x-axis. Left Y-axis on the merged graph showâ€â"¢s the current graphâ€â"¢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 graphâ€â"¢s Y-axis becomes X-axis of merged graph. Y-axis of the graph that was merged becomes merged graphâ€â"¢s Y-axis.

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.

What does vuser_init action contain? –

Vuser_init action contains procedures to login to a server.

What does vuser_end action contain? –

Vuser_end section contains log off procedures.  

What is think time? How do you change the threshold? -  

Think time is the time that a real user waits between actions. Example: When a user receives data from a server, the user may wait several seconds to review the data before responding. This delay is known as the
think time. Changing the Threshold: Threshold level is the level below which the recorded think time will be ignored. The default value is five (5) seconds. We can change the think time threshold in the Recording options of the Vugen.

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.

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.

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. 

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 concurrent Vusers
  
• The number of hits per second
  
• The number of transactions per second
  
• The number of pages per minute
  
• The transaction response time that you want your scenario
  

Analysis Scenario (Bottlenecks):

In Running Vuser graph correlated with the response time graph you can see that as the number of Vusers increases, the average response time of the check itinerary transaction very gradually increases. In other words, the average response time steadily increases as the load
increases. At 56 Vusers, there is a sudden, sharp increase in the average response
time. We say that the test broke the server. That is the mean time before failure (MTBF). The response time clearly began to degrade when there were more than 56 Vusers running simultaneously.

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.

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.

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.

How many types of Vusers are available?

There are several types of Vusers
1. GUI
2. Database
3.RTE(Terminal emulator)
4. SAP
5. DCOME
6. Peoplesoft
7. Java
8. BAAN

VuGen contains the 3 sections.
1. Vuser-init
2. Action
3. Vuser-End

What is runtime setting?

Runtime setting includes loop.log and timing information.

 What is standalone mode?

It is the mode to verify that the script runs correctly or not.

What type of function generate and insert by the VuGen to the script when you record a script?

1. LR function (Vuser function)
2. Protocol function.

How VuGen create a Vuser script?

By recording the activity between client and server

How you edit the script?

While editing the script we have to insert the transaction point and rendezvous point.

What is the load runner start transaction and its syntax?

It will start the transaction on the script.
Syntax: Lr-start-transaction("transaction name")

What is the load runner end transaction and its syntax?

It will end transaction.
Syntax: Lr-end-transaction("transaction name", LR-AUTO)

Where you insert the rendezvous point?

Rendezvous point inserted into script to calculate the peak load of the server.
Syntax: lr-rendezvous("rendezvous point")

What are the elements in the load runner controller?

Title bar ( Name of the scenario presently working). Menu bar ( selecting the various command ). Tool bar. status bar.

What are the 5 icons appear in the bottom of the controller windows?

1. Host windows (list of machines)
2. Script windows (list of all the vuser script)
3. Rendezvous windows
4. Transaction windows(display all the transactions )
5. output window(Display error and notification message)

What is .lrs?

Loadrunner save the information in a scenario files.

What is scenario wizard?

Through scenario wizard we can create a new scenario.

What is filtering and sorting?

We can filter the information display only those items that meet the selected criteria(filter box) exam you can filter Vuser only those who are in ready state.
Sorting we can sort all the Vuser in the vuser list. In order to their vuser ID(1,2,3,4,5,6,7,8,9).

What is the information creating for each host?    

1. The status of the host.
2. The platform type of the host(window/unix)
3 Details of the scenario.

How to create a host list for a scenario?

1. Install remote command launcher on every machine.
2. Add the name of the host to the host lists.
3. Set attributes for each host.
4. Select which hosts will take part in the scenario?

What the host attributes determine?

1. The maximum number of vuser that host can run.
2. The initialization quota.
3. The location of the winrunner configuration file.
4. The location of the file during runtime.

How you set maximum number of vuser that a host can run?

We can modify the maximum number of Vuser according to the (available resource, the needs of yours scenario, Loadrunner license arguments).

What do you mean by initialization of quota?

Capabilities of the host that at a time how many vuser are initialize.

 

What protocol does LR supports?

Industry slandered protocols .For EX: HTTP and ODBC are explicitly supported by LR. Further more any protocol that communicates over a windows socket can be supported.

What do i need to know to do load testing in addition to knowing how to use the LR tool?

In addition to knowing the tool:
-management aspects of load testing, planning being paramount
-requirements gathering, profile/mix,SLA,acceptance criteria
-an general understanding of the protocol yo are working with, developers can be unhealpfull
-a basic understanding of c programming
-know that you will be working wit demising time scales and you are really at the end of the life cycle
-as a result of the above you may have to work unsociable covers including week ends
- managers and other "Powers that be"-"BOX tickers" will not understand your plight
You need to be able to communicate effectively at all levels wit different departments from business to Dev to system testing
-voice your problems as soon as possible- planning
-fail to plan - plan to fail

What can i monitor with LR?

Monitor system bottle necks during a test run can capture and display the performance data from every server or component.

How many users can i emulate with LR on a pc?

Unlimited, no dead end.
Depends on system response. That to in turn depend on various factors like entire system configuration etc.
If system bottleneck observes in very beginning or minimum number of Vusers no further addition of Vusers will be considered unless observed bottle neck is resolved.

What r the Vuser comp[components in the LR?

Application components used are client, data base or additionally business application server
Web server works on and through LAN, WAN or WWW. connection.
Application server components are client, business server and data base server with out use of www but through protocols like ftp.

LR function - How to get current system time?

This function is developed to use in mercury load runner performance tool. The main use of this function to return the current system time at any given point of time while LR script is running. This function can be used to report transaction times, script start time and end time.
long get_secs_since_midnight(void)
{
char * curr_hr;/*pointer to a parameter with current clock hr */
char * curr_min;/*pointer to a parameter with current clock min */
char * curr_sec;/*pointer to a parameter with current clock sec */
long current_time; /*current number of seconds since midnight */
hr_secs;/*current hour converted to secs */
min_secs;/*current minuets converted to secs */
secs_secs;/*current number of seconds */
curr_hr=Lr_eval_string("{current_hr}>");
curr_min=Lr_eval_string("{current_min}");
curr_sec=Lr_eval_string("{current_sec}");

hr_secs=(atoi(curr_hr)) *60 * 60;
min_secs=(atoi(curr_min)) * 60;
secs_secs=atoi(curr_sec);

current_time=hr_secs+min_secs+secs_secs;

return (current_time);
}

What are the reasons why parameterization is necessary when load testing the web server and the data base server?

Parameterization is generally done to test with multiple set of data or records.

What is LR?

LR accurately measure and analysis the system performance and functionality .

When LR is used?

When multiple users were work concurrently

What is the advantage of using LR?

1. LR automatically records the performance of the client server during test.
2. LR ckecks where performance delauys occure netwoerk client delays.
3. LR monitor the network and server resource to help the improve performance.

What do you mean by remote command launcher?

RCL enables the controller to start the application on the host machine.

What is loadrunner agent?

Agent is interface between host machine and controller.

When the load runner controller opens the WinRunner file, then what is the location of the winrunner configuration file?

Wrun.ini

What is scenario default?

 

Instruct the Vuser to use the winrunner configuration file.

What is local configuration file?

Instruct the Vuser to use hosts winrunner configuration file.\ What do you mean by path?
Use winrunner configuration file i.e., in a specific location on the network.

During run-time where the hosts saves the files?

In temporally in the local drive of each host.

What is script list?

It contain all Vuser script that Vuser can run.

What are the information contained by script windows for each script in the list?

1. Name of the Vuser script.
2. Type of the Vuser script.
3. location(Path).
4. command line option.

how to modify the script?

Using vuser script information dialog box.

What is the purpose of running the scenario?

To check the response time of client or server system under load.

Why we insert the rendezvous point while running the scenario?

If a multiple Vuser to perform a task at exactly the same time.

When a scenario run a exactly, what happens?

1. The controller checks the scenario configuration information.
2. Then next it invoke the application that you select to run with the scenario.
3. Then transform each script to its related hosts, when the vuser are ready they start execution.

How to run a scenario?

Open an existing scenario
Configure the scenario
set the result directory
Run the scenario

When you initialize the Vuser what happens?

The Vuser status change from DOWN to PENDING to INITIALIZING to READY.
If Vuser files to initialize, the Vuser status changes to ERROR.

What is pause command?

It changes the status of the Vuser from RUNNING to PAUSE.

What is running virtual user graph?

It displays the number of Vusers that execute vuser script during each second of the scenario run. Only running and rendezvous state are include(loading, ready and pause are not displayed).

What is report viewer?

Each report viewer contains the report header and report viewer tool bar.

What is report header and what are the information contains?

It display general scenario information and it contains the information like title, scenario, result start time, end time and duration.

What is rendezvous graph?
It indicate when Vuser were released from rendezvous point and how many Vuser are released from each point. It help the transaction performance time.

What is transaction per second graph(PASS)?

It display the number of completed, successful transactions performed during each second of scenario run.

What is percentile graph?

The percentage of transaction that were performed within a given time range.

What is transaction performance graph?

Displays the average