Preface

The performance test is mainly used to check whether the system performance meets the requirements

The above is the performance test process

1. Demand analysis , Analyze the system performance index
2. Prepare the environment 、 Tools and scenarios
3. Preparation script , Complete test preparation based on different performance scenarios
4. Execute the script , get data
5. Determine whether the index meets the requirements
6. If it meets the standard , The next performance test will continue , Understand system thresholds , Test whether the system has anti risk ability
7. If it does not meet the standard, enter the performance diagnosis
   such as ：CPU Occupy too much , Response time decreases , Throughput drops , The occupation of hardware resources has increased
   First, check that the process occupies too much memory , Check which thread in the process caused , From thread to code
8. Give optimization suggestions to developers

Tips ： The following is the main body of this article , The following cases can be used for reference

Example 1： Homepage support 5 Concurrent users , Time in 3s Inside , The fault tolerance rate shall not exceed 2%

1、 New thread group

1、 Thread group is equivalent to user group , How many threads are equivalent to how many users , All samplers are under the thread group , All tasks are based on thread groups ;
2、ramp-up period It is the time required to start the set thread . If you choose 10 Threads , also ramp-up period yes 5 second , that JMeter Will use 5 Seconds make 10 Threads up and running .1s Just start two threads .（ The time required to start the thread is set by yourself , It is set according to the server performance of the project , If the setting time is too short , Insufficient server performance , It will also affect the results of subsequent implementation ）
3、 The cycle is the number of times the cycle is executed in the specified time . For example, the number of threads 10, Time is 5 second , loop 2 Time , in other words , Two threads will be executed in one second 2 Secondary cycle , One second concurrent 4 Requests ;

Support 5 Concurrent users , Setting the 5 Users

2、 Set up HTTP request

Setup protocol 、IP、 port 、 route
Take Baidu for example

3、 Set listener

1. Number of users , First set the listener for the number of active threads （active threads）
2. response time ——response over time
3. Error rate —— Aggregation report
   

4、 start-up

5、 View results

1. First, check the number of active threads

Get close to... As soon as possible 5 s Start , The red line is nearly flat , All users are running , So when viewing the response time report , It should also start from 5s Start looking at ,20 end
2. Check response time

From 5 Seconds to check the response time , Maximum not exceeding 800 millisecond
3. Check the error rate
Open aggregate Report

The abnormal rate is 0, And percent 99 In the time of , The average response time is 133 millisecond , Meet the requirements of this performance test

Example 2： The response time of visiting the homepage shall not exceed 3s, How many concurrent users can be supported ？

Two kinds of schemes ：
（1） Based on server performance , Estimate a maximum number of users , According to the test results , Add the number of original users （ Or minus ） Half of the original number of households （100 user , Performance has not reached the bottleneck , The number of people is 100+100/2=150）, Know the maximum number of users obtained
（2） every other 10s Add a user
The second method is used here

1、 New thread group

Gradually pressurized thread groups are used ultimate thread group（ It is more accurate than ordinary thread groups , Because the average value is taken when adding users to ordinary thread groups , As long as 10s Can be completed ）

2、 add to http request

And examples 1 Agreement , It can be copied directly

3、 Listeners and results

The response time of visiting the homepage shall not exceed 3s, How many concurrent users can be supported

1. Number of users , First set the listener for the number of active threads （active threads）
2. The relationship between response time and the number of users （response times vs threads）
3. error —— Aggregation report 、 View results
   
   
   According to the above results, the number of users can be modified to the initial number of threads 700, Increase per second 5 Number of threads
   Until finally 3s How many concurrent users are supported in