Introduction to the concept and parameters of performance testing

What is a performance test?

There are many online, to say the concept must first say classification, performance testing, stress testing, load testing, capacity testing ... In my opinion, just according to different test purposes (that is, to achieve the results) and the different names, the means are the same, it is not only to simulate the concurrent user to access the system, through the analysis of the parameters to evaluate the performance of the system.

The first stress test, the stress test, is the constant pressure test of the software, which is to obtain the maximum service level that the system can provide by determining the bottleneck of a system or the performance points that cannot be received.

A brief introduction to the stress test we are concerned about several parameters, generally our service and machine two types of parameters.

First the server, we say a good system should be "high concurrency, low latency", concurrency and response time is the two most important parameters

1 concurrency : the ability of the system to process transactions at the same time, usually with the QPS (query per second), and with RPS (request per second), the TPS (throughput, which should be exactly the throughput rate).

2 Response Time: The client makes a request to the time it receives the return. For example, I visit baidu.com, press ENTER after the 1s opened the Baidu home, the response time is 1s. The time of this process includes = Network transmission time + Service processing request time, especially for a non-Web request, if my own network environment is not good, it will cause the transmission time is too long, so also someone only use the service processing request time to express response time. I think both can be, as long as the report is written in the test environment and the meaning of the field.

3 Error Rate: The front two is the efficiency, this is the quality. If the returned content is not returned successfully, it is counted here. The test can be alert based on the returned status code or the returned content.

Second, the machine environment, mainly from the aspect of the protection hardware, the two need to pay attention to the parameters are CPU and load, as follows.

1 CPU: the logical processing power of the computer. CPU utilization reflects the use of the CPU, when the CPU is in use for a long time without getting enough rest interval, then for the CPU hardware is an overloaded operation, need to adjust the frequency of use.

2 load Average: is the load of the CPU , it contains information that is not CPU usage status, but the CPU is processing and waiting for a period of time Statistics on the sum of the number of processes processed by the CPU, that is, the length of the CPU usage queue. from another point of view, for a description of the CPU usage status, the higher theLoad average, the more intense the competition for CPU resources, the lessCPU resources. In fact, the application and maintenance of resources also need a great cost, so in the case of high Average load, the long term "hot competition" of CPU resources is also a kind of damage to hardware.

Well, it's all taken from someone else's house. If your machine is dual-core, then your process takes up CPU 100%, which takes up half the CPU resources of the machine, and the load is 4, which means that 4 of the current queue needs to be processed, and your CPU is limited to processing only 2, so there will be queue accumulation. So doing performance testing needs to focus on the CPU and load to keep your program running in a good environment.

Commonly used about these several, if later found a special parameter, and then add ~

Introduction to the concept and parameters of performance testing