senthil_kumar84

 Profile Answers by senthil_kumar84 

• Feb 27th, 2007

 

Both are same. concurrent or simultaneous users are nothing but the number of virtual users running at the same time.

Ashish Gharde

• Mar 1st, 2007

 

Simultaneous users have active connections to the same Web site, whereas concurrent users hit the site at exactly the same moment. Concurrent access is likely to occur at infrequent intervals. Your site may have 100 to 150 concurrent users but 1,000 to 1,500 simultaneous users.

When load testing your application, you can simulate simultaneous users by including a random think time in your script such that not all the user threads from the load generator are firing requests at the same moment. This is useful to simulate real world situations.

However, if you want to stress your application, you probably want to use concurrent users. You can simulate concurrent users by removing the think time from your script.

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Regards,
Ashish Gharde

kanthrajgowda

 Profile Answers by kanthrajgowda 

• May 23rd, 2008

 

There is a big difference between simultaneous and concurrent users in load testing world.

Simultaneous users: Lets say that users are logging into application, send a mail and logout. In this process, every user will wait for the other user to complete the entire transaction before logging. here at any point in the scenarion no 2 users are logged in to the system. simple words one after the other.

Concurrent users: There are 3 different levels of concurrency.
1. Application level
2. Business process level
3. Transaction level

Taking the above example
Application level : two users login but one user can send a mail and other can read a mail. Notice 2 users although active at the system at the same time, they perform 2 diffferent processes.
Business process level: two users login to the system and send mails. But they dont login at the same time and send mails. It can so haapen that one user is coposing amil, 2 nd user logs in. first users sending  a mail, second user composing. ...and so on..Point to notice here is 2 u sers are active on the system doing the same busineess process but niot all actions at a time.
Transactin level: 2 users login at teh same time, compose at the same tiem and sends mail at the same time and logs out at teh same time. (Randezvous).

Overall when we say 10 concurrent  users, 10 users are currently active on the system at that point of time. When we say 10 simultaneous users which is not the case.

I hope this will clarify the question in detail.

Regards,
Kanthraj.
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