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Saturday, February 28, 2009

LoadRunner Architecture

LoadRunner works by creating virtual users who take the place of real users operating client software, such as Internet Explorer sending requests using the HTTP protocol to IIS or Apache web servers.
Requests from many virtual user clients are generated by "Load Generators" in order to create a load on various servers under test.
These load generator agents are started and stopped by Mercury's "Controller" program. The Controller controls load test runs based on "Scenarios" invoking compiled "Scripts" and associated "Run-time Settings".

Scripts are crafted using Mercury's "Virtual user script Generator" (named "V U Gen"), It generates C-language script code to be executed by virtual users by capturing network traffic between Internet application clients and servers.

With Java clients, VuGen captures calls by hooking within the client JVM. During runs, the status of each machine is monitored by the Controller.

At the end of each run, the Controller combines its monitoring logs with logs obtained from load generators, and makes them available to the "Analysis" program, which can then create run result reports and graphs for Microsoft Word, Crystal Reports, or an HTML webpage browser.

Each HTML report page generated by Analysis includes a link to results in a text file which Microsoft Excel can open to perform additional analysis.

Errors during each run are stored in a database which can be read using Microsoft Access

Where is Load Testing usually done?

The Load testing is carried in the controlled environment based on the requirement specs from the client the Load Test Plan followed with the scenarios are created & executed to match the requirements. To speak more precisely the Load testing Episode is carried once the Performance exercise is done, finding the System bottlenecks & Tuning and Fixed.

How do we do performance and Load Testing using LoadRunner?

LOAD TESTING: First generate the script using virtual user generator or astra quick test. Run the generated script in the load runner controller. While doing this run time settings are to be modified according to the specifications required. Eg. ignore think time, ignore content in the application etc..
In run time settings, choose the numbers of virtual users to run the application simultaneously. let all the virtual users begin from the same point. Once you click start scenario the load test begins.
Points to consider after stopping the application:
1, The number of throughputs and hits per sec have to increase as the number of virtual users increases. If throughputs flattens, we can say there are network problems and if hits per second flattens, we say connection/network problems.
2, check that all the virtual users passed the application within the specified Response Time.

How many types of graphs have LoadRunner?

There are 5 graphs on Load Runner.
1) Hits per second graph
2) pages download per second graph
3) Transaction response time (under load) graph
4) Transaction response time (percentile) graph and
5) Network delay time graph

How can we set the number of vuser in LoadRunner?

When Creating Scenario in Controller we have to add the particular script which we want to run. There we have to set the number of Vusers to run for that script. but you have to add Vusers depending on the your LoadRunner license for how many Vusers it sponsors.

What are the components in LoadRunner?

1. VU Generator - For generating VU Script for the type of Vuser under test like DB Vuser/Web Vuser

2. Controller - For creating scenarios

3.Analysis - For viewing execution resultsBased on exp with loadrunner 5.0

What is Elapsed time in LoadRunner?

In LoadRunner Analysis, you have to set Elapsed time for getting transaction response time related to elapsed time. For this you have to use Filter Icon in the Analysis result file. For ex: the test run is 1 hr but you want the transaction response time from 25 min to 55 min in that one hr. In Elapsed time you have to set FROM and TO period so that you can get the transaction response time in that period only

What are the advantage of using load runner ?

1-loadrunner automatically records the performance of the client/server during test.

2-loadrunner checks where performance delays occur network/client delays.

3-loadrunner monitor the network and server resource to help the improve performance.

what is the level of system loading expected to occur during specific business scenario?

It depends on the application at hand, the network, number of users involved, the database etc. I doubt if I have a generic answer for telling you the amoung of load that would be expected during a specific business scenario.

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

Initially run the application with one user. Save the increase the load to ,15,50,100,500,1000 slowly.During the process, you will find the system will break down for a particular number of virtual users. From there start decreasing the load and u will find the bottle neck for the application so that u can call for the quality meeting.

What is Correlation in LoadRunner?

Correlation is the identifying and resolving data which are , unique for each run of the script or each iteration of an action. These dynamic data differ in each replay from the original recording and causes the replay to fail.

Friday, February 27, 2009

Where is Load Testing is usually done?

The Load testing is carried in the controlled environment based on the requirement specs from the client the Load Test Plan followed with the scenarios are created & executed to match the requirements. To speak more precisely the Load testing Episode is carried once the Performance exercise is done, finding the System bottlenecks & Tuning and Fixed

Thursday, February 26, 2009

what are the advantages of using Load Runner?

1-loadrunner automatically records the performance of the client/server during test.
2-loadrunner checks where performance delays occur network/client delays.
3-loadrunner monitor the network and server resource to help the improve performance.

What is transaction ?

Transaction measure the time which takes for the server to respond to task submitted by the vuser.

What is the host attributes determine?

1-the maximum number of vuser that host can run.

2-the initialization quota .

3-the location of the win runner configuration file.

4. the location of the file during run-time.

Load Runner Functions - How to get Current System time?

This function is developed to usein Mercury Load Runner peformance tool. This main use of this functions to return the current system time at any point of time while load runner script is running.This functiona can be used to report transaction times , script starti 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 minutes 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;


What is the vuser in the scenario?

Load runner replace the human user with vuser. Latest Answer : Vusers are virtual users (dummy users )which are going to emulate & emutate as a real user.

What is the vuser script contains?

The vuser script include the function that measure and record the performance of the server during the scenario. Latest Answer : While recording the application, a script will be generated in the virtual user genetator. According to the script generated, the created virtual users will perform the operations

What is LoadRunner Controller?

Controller is manage and maintain the scenario . using controller you control all the vuser in single work station . Latest Answer : Controller is a one of the Component in Loadrunner. It uses to design the multi user scenarios and run the scenarios against the load behaviours. In the controller you can design the Benchmark test, Load test, Stress test, Spike test, Endurance టెస్ట్


When the Rendezvous point is inserted?

When multiple vuser to perform tasks at exactly the same time then insert the rendezvous point to emulate the peak load on the server.

The "Rendezvous point" could be inserted at the moment, when exactly you wanted the Vusers to act simultaneously.

For Example,

You can find a start and end Transaction, in the script if you have generated.

Insert the rendezvous point, just before starting the transaction.

This implies that, all the Vusers are asked come and reach at the point before starting the transaction, and perform the operation at that particular time.

What are the Loadrunner Testing Process?

There are 5 steps.
1-planning the test.
2-creating the vuser script.
3-creating the scenario.
4- running the scenario.
5-analysis the test result.

What are the process for developing a vuser script?

There are 5 steps for developing a vuser script.
1-recording the vuser script .
2-edit the vuser script.
3-runtime setting .
4-run the vuser script in stand-alone mode.
5-incorporate the vuser script into a load runner scenario.

When LoadRunner is used?

as we all know that functionality testing helps ensuring that the product/application works fine according to the requirments and the client verifications are validated. This is always done by single user and depending upon the complexity of the application or the product, many test cases are written to ensure that the components functions as intended, but when the application passes this TollGate of functional testing, there is always question of what will happen to the application/product when multiple users are accessing them. Here comes the load testing which ensures that the application performs without breakdown for the required users as indicated in the CS ( customer specificatio ) document. For this we need to ensure proper loadtesting is done using automation as we all know we cannot ask 50 real users sitting b4 a computer and click is done, moreover all the areas of concerned will not be covered. One such loadtesting automated tool is loadrunner which is used to emulate the behaviour of real time user. Here the loadrunner is used, there are other load testing tools in the market but Mercury stand in forefront.

What Protocols does LoadRunner Support?

The Vuser types are divided into the following categories:
➤ All Protocols: a list of all supported protocols in alphabetical order.
➤ Application Deployment Solution: For the Citrix protocol.
➤ Client/Server: For DB2 CLI, DNS, MS SQL, ODBC, Oracle (2-tier), Sybase Ctlib, Sybase Dblib, and Windows Sockets protocols.
➤ Custom: For C templates, Visual Basic templates, Java templates, Javascript and VBscript type scripts.
➤ Distributed Components: For COM/DCOM, Corba-Java, and Rmi -Java protocols.
➤ E-business: For FTP, LDAP, Palm, Web (HTTP/HTML), Web Services, and the dual Web/Winsocket protocols.
➤ Enterprise Java Beans: For EJB Testing and Rmi-Java protocols.
➤ ERP/CRM: For Baan, Oracle NCA, Peoplesoft-Tuxedo, Peoplesoft 8, SAPGUI, SAP-Web, and Siebel (Siebel-DB2CLI, Siebel-MSSQL, Siebel-Web, and Siebel-Oracle) protocols.
➤ Legacy: For Terminal Emulation (RTE).
➤ Mailing Services: Internet Messaging (IMAP), MS Exchange (MAPI), POP3, and SMTP.
➤ Middleware: Jacada and Tuxedo (6, 7) protocols.
➤ Streaming: For MediaPlayer and RealPlayer protocols.
➤ Wireless: For i-Mode, VoiceXML, and WAP protocols.

Referrd by Loadrunner8.0 documentation guide.

What do u mean by createing vuser script?

Creating vuser script for emulate the action that virtual user Perform during the scenario execution.

What is rendezvous point?

Rendezvous Point is the point where all the Vusers arestopped at one point and are released at the same time as to obtain concurrency.
During a scenario, you can instruct multiple users to perform tasks simultaneously by inserting rendezvous point.It create intense load on the server and enables Load Runner to measure server performance.The users who arrive at this point wait for other users to come at the point and they simultaneously perform the task.We need to set the following in the rendezvous policy -Release policy - How many Vusers will be released from a rendezvous at a time.Timeout - How long the Controller waits before releasing Vusers from a rendezvous
It allow the Vusers to generate peak load on the server at the same time.For example if there are 100 Vusers, the rendevous point allow the 100 vusers to access the webpage at the same to check the peak load.