Since the load profile typically has multiple operations – this means that we will have several groups of users. It is desirable to simulate each operation a separate group of virtual users (although it is often the opposite of life, a business user may be responsible for the execution of multiple operations). However, if you assign one virtual user to perform one operation, then it is easier to sustain a certain intensity (and performance) for this operation in the test than in the case where the virtual user is assigned a sequential chain of operations. Knowing the intensity of the operation to determine the number of virtual users in the group performing this operation. The ideal case when you open the program is similar to working the assembly line and have accurate estimates of how many transactions a day makes one user. More often than not and we know only the total number of operations performed during the day. There may also be that the intensity of the operation each user is very low, for example, a user performs an operation on a daily or every other day.
Simulation of the recalculation of the intensities in this case can be illustrated by the following example
EXAMPLE: (for one operation)
The number of operations = 200 in 4 hours
The number of business users = 20
1. Determine the number of transactions for each user
200/20 = 10
2. At the hour of each user performs the operation 2.5
10 / 4 = 2.5
3. Define the repetition period of operations (intensity) for each user
60/2.5 = 24 minutes
4. To reduce the test time to an hour and still get any statistics on what the procedures, as well as to improve the "mixing" of operations during the test, you can increase the intensity of 4 times, while reducing the number of users as a factor of 4.
24 / 4 = 6 min. = 360 seconds
Thus, 5 virtual users performing an operation with a period of 6 minutes, will provide 4 hours given the performance of 200 operations.
First, it is possible to reduce test time, without losing the statistical operations and, consequently, the reliability of test results.
Secondly, it is possible to reduce the number of simulated users where the number goes over a few thousand, and thus reduce the requirements for the number of resources load of computers (1VU may require up to 10MB RAM pamyatinagruzhayuschego computer), and in some cases, fulfill the conditions of the license agreement (license cost for test equipment depends on the number of virtual users)
For some applications, may be critical number of simultaneously opened connections between client and server. There are situations when queries to the database began to work much slower than if using the application increases the number of users is different (different logins) but not the intensity of the requests. Finally, the increased intensity of operations, should not lead to a situation where the return period is less than the run time of the operation itself.
In any case, despite some limitations, such calculations can tolerate variation in the number of virtual users and the intensity of the performance of operations. The productivity and therefore the load should not change and be different from the set. Thus, the load point involves calculation of virtual users and intensities for all operations of load profile.