Shulou(Shulou.com)06/02 Report--

Aggregation of indicators is a common means in the field of application performance management, which is mainly used to aggregate hundreds of indicators into one or more indicators through some calculation method to reflect the overall health status of the application. Among these aggregation indicators, the more common one is the APDEX application performance index.

The "application performance index", or "Apdex" (Application Performance Index), is summed up in one sentence. Apdex is a quantified value of user satisfaction with application performance. It provides a unified method of measuring and reporting user experience, linking end-user experience with application performance for the first time. Based on "responsiveness", Apdex defines three user satisfaction ranges:

Satisfaction: this response time makes the user feel happy, for example, less than 3 seconds.

Tolerance: it's a little slow, but it's acceptable to continue the application process, for example, 3-12 seconds.

Disappointment: it was too slow to stand it, and the user decided to abandon the application, for example, more than 12 seconds.

The three intervals of "satisfaction", "tolerance" and "disappointment" are divided by the response time value "T". The T value represents the response time limit or "Threshold" of the user's satisfaction with the application performance, that is, the bottom line of the first interval of "satisfaction". For example, 3 seconds, the satisfaction interval is 0 seconds. Users are dissatisfied when the response time exceeds the T value, and the threshold value of the next interval "tolerance" is T and 4T, that is, between 3 and 12 seconds, and the longer the response time is, the users begin to consider giving up. The response time of "disappointment" in the last interval is more than 4T, that is, more than 12 seconds.

After that, Apdex samples the tasks that occur in the application, divides the samples into corresponding satisfaction intervals according to their response time, counts them, and calculates the Apdex index with a formula:

In fact, the meaning of this formula is:

A satisfactory sample is scored as follows: 1

A tolerance sample score: 0.5

A disappointment sample score: 0

So the formula can also be written as follows:

Apdex index = (1 × satisfactory sample + 0.5 × tolerant sample) / total number of samples

In this way, the sampling result is quantized as a value between 0 and 1, that is, the "Apdex index". 0 indicates that there are no satisfied users, and 1 represents that all users are satisfied. According to statistics, Apdex refines this value to correspond to user satisfaction. As shown in the following figure, the Apdex score for application performance is closely related to user experience, providing managers with a method to evaluate user satisfaction through the quantitative value of application performance.

In addition to Apdex, the aggregate index of RealSight APM also has "health".

From the above introduction, we can understand that Apdex mainly reflects the indicators related to user experience, so we hope to have another indicator to reflect the surrounding environment of the application, focusing on hardware resources such as CPU, memory and other information, so we use "health". Its basic principle is the same as Apdex, dividing into different satisfaction intervals, and then calculated.

RealSight APM is committed to one-stop solution to enterprise application performance management problems.

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