What is the difference between stress testing performance testing and load testing?

Answer 1

Let me explain with an example.

Yahoo has a website. We know that million of people are going to access this site every day. In fact thousands will be clicking this website at same movement of time.

But Yahoo has limited hardware capability. Now they want to know how many people can access their website (hitting their servers) at the same time.

1. Load testing - is expected rate is matched? Yahoo estimated that a maximum of 90,000 people (example) can hit at any point of time. So load testing is performed that whether with 90,000 virtual users system is performing well or not?

2. Stress testing - if we slowly increase users from 90,000 to say 91,000 then to 92,000 then to 93,000 and so on...then at what time servers crash or site stopped responding?

3. Performance testing - Suppose with one user yahoo page opens in 1 sec. Then with 1000 users is it opening in 1 sec? then with 50,000 users hitting website at same time, is it opening in 1 sec....so what is performance of website up to a desired level? (up to 90,000 in this example)

*************

Above are good differences. I got clear 10 differences between load and stress testing with example

conceptsimplified.com/compare/load-stress-testing/

Answer 2

Stress Testing is subjecting a system to an unreasonable load while denying it the adequate resources as required to process that load. The resources can be RAM, disc space, mips & interrupt etc. The idea is to stress a system to the breaking point in order to find bugs, overload without adequate resources, but to fail in a decent manner (e.g.,failure without corrupting or losing data). In stress testing the load (incoming transaction stream) is often deliberately distorted so as to force the system into resource depletion.

Performance testing is the process of determining the speed or effectiveness of a computer, network, software program or device. This process can involve quantitative tests done in a lab, such as measuring the response time or the number of MIPS (millions of instructions per second) at which a system functions.

Load Testing is a test performed with an objective to determine the maximum sustainable load which the system can handle. Load is varied from a minimum (zero) to the maximum level the system can sustain without running out of resources or causing excessive delay in transactions.

http://www.softwaretesting-certification.com/