Performance test (I)

Why performance testing

• Whether the application can quickly respond to user requirements .
• Whether the application can handle the expected user load and has surplus capacity
• Whether the application can handle the number of transactions required by the business
• Under expected and unexpected user loads , Whether the application is stable
• Whether it can ensure that users get a comfortable experience when using the software .

What does performance testing focus on

• Number of concurrent users / throughput
• Mean response time
• Server occupancy
• reliability 、 Extensibility
• soft 、 Whether the hardware configuration is appropriate

Who cares about performance

（1） Developer

• System architecture ： Is the architecture design reasonable
• Database design ： Whether there are problems in database design
• Code ： Is there a performance problem in the code , Whether the system has unreasonable memory usage
• Design and code ： Whether there is unreasonable thread synchronization and unreasonable resource competition in the system

（2） System manager

• Resource utilization ： Is the usage of application server and database resources reasonable
• System capacity ： How many users can the system support at most , What is the maximum business processing capacity of the system
• system stability ： Does the system support 7*24 Hours of business access

（3） user

• response time ： For one web For the website , The general standard principle is 3/5/8
• system stability ： Whether the system is stable during operation

（4） Business people
How to provide parameters to users , for example ： How many users are supported to use 、 What's the response time
（5） Testers
All the above levels should be concerned about .

Concept

Number of concurrent users

（1） Number of concurrent users in a narrow sense ： At the same time , Use the same function of the system （ Send a request ） Of users .
（2） Generalized number of concurrent users ： At the same time , Put pressure on the server （ Send a request ） Of users .（ It can be different functions ）

response time (RT)/ Mean response time (ART)

The time between the user sending the request and the expected result .

Transaction response time (TRT)

A transaction is a collection of closely related operations .
The time taken by the server to process a transaction .

Number of transactions passed per second (TPS)

TPS Is the number of transactions that the system can process per second

Click through rate

Number of messages sent to the server per second HTTP Number of requests .

throughput （ Throughput rate ）

The amount of information processed by the server per unit time .

Resource utilization

Usage of different system resources . contain CPU, Memory , Hard disk , Network, etc .

Performance test categories

The benchmark

Test the performance of a new system , Record all performance indicators , As a benchmark for subsequent performance tests .

The load test

Capacity the system , Increasing the load on the system （ The number of users ）, See how much user load the system can bear , See whether the system has reached the required performance indicators .

pressure （ Strength ） test

To find out the performance bottleneck of the system , And the causes of system performance bottlenecks .
Generally, the user load of the system reaches saturation and runs for a long time , Check whether the system resource allocation is reasonable 、 Synchronization problem 、 Memory leak 、 Check the reason .

Configuration testing

By testing different application servers , The network environment , Different parameter settings of the database , Different hardware devices , Check the performance of the system , Find out the best and most reasonable resource allocation .

Reliability test

Run the system for a long time , View the performance indicators of the system （ response time 、TPS、 Click through rate 、 throughput 、 Resource utilization ） Is stable .