Simultaneous users and Concurrent users

Q. What are the simultaneous user? What is the use of simultaneous users?

Ans: When all the users wait at the point and then hit the server at the same point of time without any delay. Such type of users is called simultaneous users.

Simultaneous users apply the full load at the particular functionality to find out the performance of it. A load of simultaneous user confirms that the particular page or functionality of the application can handle the desired load or not at a time.

Example: Tatkal reservation at IRCTC site

Q. What are the concurrent users? What is the use of concurrent users?

Ans: Concurrent users are those users which all are active in the system at a point in time but can do different tasks. You can simply say that they are parallel active users performing different activities on an application.

Concurrent users simulate the real-world scenario in the testing environment. There are very few moments when active users simultaneously hit the same functionality of the application else they remain concurrent.

Example: Behavior of the bank customers on the baking website

There is one practice scenario for simultaneous users and Concurrent Users which states:

The application must successfully handle 10 concurrent travel agents.

The application must be able to process 10 simultaneous flight bookings with response time not exceeding 90 seconds.

Point 1 implies that application must be able to handle 10 travel agent load (over a period of time) irrespective of their activities. Hence they used the term ‘concurrent’.

Point 2 implies that the application must be able to handle 10 simultaneous bookings (at a point in time). That means all the travel agents must click the ‘Book the Flight’ button at the same time. You can simulate this scenario via rendezvous point.

Some important points:

• Both the words mean “occurring at the same time”, but “concurrent” represents the events that occur over a period of time whereas “simultaneous” represents the events that occur at a point in time.
• The simultaneous user is a subset of the concurrent user.
• Simultaneous users can be concurrent users, but concurrent users cannot be simultaneous users.
• Generally, the number of concurrent users on an application is more than the number of simultaneous users.
• All the simultaneous users must be active and perform the same activities at a point in time.
• Concurrent users may be active or inactive and may perform different activities.