Calculation formulas for "Number of concurrent users", "System users" and "simultaneous online users"

The concepts associated with the number of concurrent users also include"Number of concurrent users”、"Number of system users"and"Number of simultaneous users online, a practical example is used to illustrate the difference between them.
Suppose there is aOA system, the system has2000 Users-that is, it is possible to use theThe total number of users in the OA system is2000, this concept is"Number of system users", the system has aThe online statistics"Function (the system uses a global variable to count all logged-in users), which can be obtained from the online statistics function, at peak500 people Online (this500 is what is generally said."Simultaneous online headcount"), what is the number of concurrent users of the system?
Based on our definition of the number of business concurrent users, this500 is the maximum number of business concurrent users when the system is used. Of course500 This value only indicates that at the highest point there is500 users logged into the system and did not represent the actual server pressure. Because the pressure on the server is also related to the specific user access mode. For example, in this500 x"Simultaneous use of the system"The user, examining a certain point in time, at this time, assuming that the40% of users are more interested in viewing system announcements (Note:"Look"This action does not incur any burden on the server,20% of users are filling in complex forms (for user-filled forms, onlyThe Submit"will not send a request to the server, the filling process is not pressure on the server),20% part of the users in a daze (that is, nothing to do), the remaining20% users continue to jump from one page to another-In this scenario, it can be said that only20% of users really pressure the server. Therefore, as can be seen from the above example, the actual pressure on the server depends not only on the number of concurrent users, but also on the user's business scenario.
In the actual performance testing work, the tester is generally concerned about the number of business concurrent users, that is, from the business perspective should be set how many concurrent number is reasonable, so in the later discussion, is mainly for the number of business concurrent users to discuss, and, for convenience, The number of business concurrent users is referred to directly as the number of concurrent users.
（1) Calculate the average number of concurrent users:C = nl/t
（2) Peak number of concurrent users:C ' ≈c+3 radicalsC
Formula1),C is the average number of concurrent users;N isThe number of login session;L isThe average length of the login session;T refers to the length of the time period of investigation.
Formula2) The calculation method of the peak number of concurrent users is given, in whichC ' refers to the peak number of concurrent users,C is the formula (1) The average number of concurrent users that are obtained in the The formula is derived from the assumption that the user'sThe login session is estimated to have a Poisson distribution.
Instance:
Suppose there is aOA system, the system has3,000 users, with an average daily400 users to access the system, for a typical user, the average time the user logged in from the system to exit4 hours, in a day's time, the user onlyUse the system within 8 hours.
According to the formula (1) and formula (2), you can get:
C = 400*4/8 = 200
C ' ≈200+3* radicals200 = 242
F=VU * r/t
whichF is throughput,VU represents the number of virtual users,R represents the number of requests made by each virtual user,T indicates the time spent in the performance test
R = T/ts
TS for user think time
General steps to calculate think time:
a,   first calculates the number of concurrent users of the system
c=nl/ t      f=rxc
b,   statistics The average throughput of the system
f=vu * r/t rxc = VU * R/t
c,   Count the average number of requests per user
r=u*c*t/vu
D, calculate the think time according to the formula
ts=t/r
Defect detection validity percentage dde=tdft/(TDFC+TDFT) x100%
where :tdft= all defects found during testing Span lang= "en-us" (i.e. )

Defect exclusion Validity Percentage dre= (TDCT/TDFT) x100%
Among them : All defects corrected in tdct= test , all defects found during tdft= test

Test case design efficiency percent tde= (TDFT/NTC) x100%
Where : tdft= all defects found during the testing process , number of test cases ntc= run

The following formula is more suitable for white-box testing
Feature coverage= number of test function points that have been executed at least once/test function Points total (function point)
Demand coverage= number of requirements to be validated/Total Demand Quantity (demand)
Coverage= Number of test cases that have been executed at least once/total number of test cases to be executed (test case)
Statement coverage= number of statements executed at least once/number of valid program code lines
Decision coverage=  The number of evaluation results  /  decision result Conditional coverage =  condition operation values are evaluated at least once  /  condition operation number
Decision condition coverage =  condition operation value or decision result is evaluated at least once /(the total number of conditional operation values + decision results Span lang= "en-us" >)
Context Determination coverage =  in the context of the number of decision branches executed and /( Number of contexts * context )
State-based context ingress coverage /(number of states * class total number of methods
Branch condition combination coverage =  the number of branching condition combinations evaluated /branch condition combinations
Path coverage Span lang= "en-US" >=  number of paths executed at least once /program total path

Number of concurrent users, number of system users, and number of simultaneous online users calculation formula