JMeter best practices

JMeter has some limitations especially when it is run in a distributed environment. Following these guidelines will assist in creating a real and continuous load:

• Use multiple instances of JMeter in case the number of threads are more.
• Check the Scoping Rules and design accordingly.
• Use naming conventions always for all elements.
  

How to pass command line arguments to JMeter when executed from command line

How to Execute JMeter from Command line:

Please visit: http://www.techopes.com/2014/09/how-to-run-apache-jmeter-from-command.html

How to Pass Arguments:

In most of JMeter test plans, their will be some dynamic values which will change will different executions like server IP address, admin credentials etc.

How to reference variables and functions in JMeter

While writing test plans in JMeter, you will need to use many variables to store some values like command line arguments, random values etc. and different functions to perform different operations.

Referencing variables:
In JMeter, variables are referenced with curly braces and $(dollar sign) i.e. a variable with name var will be referenced as ${var}.

Function in Apache JMeter

JMeter functions are no different from normal languages like C, C++, Perl etc. These functions take some parameters and return some value after processing those arguments. By convention, JMeter function names always starts with '__' i.e. two underscores. 

A typical function call looks like: 

Apache JMeter: How to create summary Report from jtl or csv file created by JMeter when executed from command line

Mostly you will need to execute jmeter in non-gui mode because of following two reasons:

1. To automate execution of jmeter.
2. To perform more number of operations per second: In non-gui mode, jmeter threads do not need to print data on jmeter gui.

For more information on Executing jmeter on command line,

Difference Between use and require in perl

This question is asked in many technical interviews which required knowledge of perl.

Require:

1. Usage: require EXPR
2. if EXPR is a numeric value, then script demands that i requires specified version of perl.
3. if EXPR is not numeric, then i assumes that EXPR is name of file to be included in script.
4. The included file must return true as last statement.

Perl Interview Questions

Below are some perl interview questions which will be usually asked in a technical interview:

• Difference between my, local and our in perl.
• Difference between use and require in perl.
• Perl referencing and dereferencing.
• write regular expression to test a string whether the string is proper IPv4 address or not.

Perl Arrays: push, pop, shift and unshift functions

Perl provides many functions to manipulate and access arrays. These functions makes it very easy to use perl arrays as stacks or queue's. Some of these functions are given below:

POP: 

pop function will remove and return last element of perl arrays. So, this can be used to remove element from stack if array is getting used as stack. pop function will return undef if array is empty

Difference between different types of IPv6 Addresses

Below are different types of Addresses types for IPv6 Addresses:

1. Global Unicast IPv6 Address: This Type IPv6 address is similar to public IPv4 addresses. This address can be used to identify single interface on internet. Global unicast ipv6 address is unique for each host. This address can be routed on internet. A packet sent using this type of address will be delivered to interface identified by address. 

How to Add or Remove IPv6 address on Linux machine

IPv6 is the future of internet. So, its really necessary to learn about IPv6.

/sbin/ip command can be used in Linux to add or remove ipv6 address.

Command to Add IPv6 address:

How to run Apache Jmeter from Command Line (non-gui mode)

Apache JMeter is mostly used when we need some number of threads to perform certain operations on different servers like LDAP, HTTP etc.

After creating test plan to be executed for the required server, we can click run button in jmeter GUI to run this test plan.

But mostly we will need to execute jmeter in non-gui mode because of following two reasons:

How to perform SSL operations using JMeter

Apache JMeter is mostly used when we need some number of threads to perform certain operations on different servers like LDAP, HTTP etc.

As most of the servers support secure operation i.e. using SSL (Secure Socket Layer), so we will have to perform SSL operation using jmeter over LDAPS,HTTPS etc.

As JMeter is written in java, so jmeter uses the java keystore known as cacerts. To perform SSL operations using jmeter, you need to add ca self signed certificate of the target server in java keystore.