Tuesday, February 20, 2007

What is the difference between Simultaneous & Concurrent users ?

These are the 2 terms which is often used in Performance Testing.

Simultaneous users are the users who have a valid session in the server. Each of the users would be performing different actions like one doing login , other viewing the reports, etc.

Concurrent users are the users who have a valid session in the server & they are performing the same operation at any point of time. All the concurrent users would perform login, reports download, etc at the same point of time.

Hence for a web site, the number of simultaneous users would be always greater than the concurrent users.For example , a banking web site has the workload of about 30000 simultaneous users & 5000 concurrent users.

Knowing the correct figures of simultaneous & concurrent users is very vital in order to perform performance testing of an application.

12 comments:

Arya Gaurav Siwach said...

Nice Piece of information....Few good blogs on performance testing

Cheers

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Anonymous said...

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Karthick said...

Good Explanation....

Satish D said...

Nicely explained. simple and crisp.

But check the final statement: "for a web site, the number of simultaneous users would be always greater than the concurrent users.For example , a banking web site has the workload of about 30000 simultaneous users & 5000 concurrent users."

the numbers should be reversed I guess.

Cheers.

hDef said...

how do you figure out correct figures of simultaneous & concurrent in order to perform performance testing of an application?

Anonymous said...

I guess the definition is vice versa..Simultaneous users are the ones performing same activity at some point of time.

Anonymous said...

To the point. Crystal Clear :) Thanks!

Anonymous said...

it's an old post , but it might be explained exactly the opposite way

http://learnloadrunner.com/introduction/difference-concurrent-vs-simultaneous-vuser/

Anonymous said...

Indeed good differentiation! But, it is in contrast to the definitions given in LoadRunner's world! They say exact opposite things...
Concurrent users - active users who may or may not do the same task at a time
Simultaneous users - They perform the same task at the same time.

Confusing!! Which one should be referred to?

Anonymous said...

Hi,
I Think you mentioned vise-versa.
If you dont mind Can you please check once again..