Performance test - analyze requirements

Preliminary preparation for demand analysis

• Collect performance requirements ： Including business transactions 、 Business volume 、 Business volume trends 、 User information 、 System architecture 、 Business indicators 、 System hardware index, etc ;
• Analyze the performance requirements of the collection ： Determine the scope of the performance test , What can be measured , Which should be tested 、 What are the indicators of the test ; Analyze user usage , Distribution of business volume , Business volume ; Estimate TPS And the number of concurrent users ;

Performance test indicators

• Business indicators ： Include TPS、RT、 Transaction success rate ;
• Hardware performance index ：CPU Usage rate 、 Memory utilization 、 Disk utilization, etc ;

The main content of performance test collection

• System architecture ： Middleware configuration 、 Database configuration, etc ;
• Business volume information
• Expansion trend of business volume
• Whether the system has archiving mechanism
• Peak period of business volume
• The number of online users of the system 、 Number of active users 、 Business distribution ;
• Whether the system is associated with a third-party system ;
• System business performance index
• System hardware index

Take a chestnut

With jforun Forum as an example for performance testing ;
1) The collected demand information is shown in the following table ：
The main function information of the forum can be given through the requirements document , For example, what can a forum do , Other information needs to be given through statistical tools , Take Baidu statistics as an example Statistical tools


The above is the collected data , With this data, we begin to analyze the performance requirements , Including throughput TPS、 Guess the number of concurrent users ;
2) Analyze performance test requirements （TPS、 Number of concurrent users, etc ）

• Business volume ： Through statistics, we can get the date PV Quantity is 2 ten thousand , The system expansion trend is 3 Annual growth 30%, therefore 3 Day after year PV≈2*（1+30%）*（1+30%）≈3.38 ten thousand
• TPS： Average transactions per second . According to the forum system , Sending a new post is a matter , Replying to a new post is a matter ;
  and pv It represents a page request , Only the requested content may include pictures 、JS etc. , When calculating PV≈TPS;
  Calculation TPS It is usually calculated according to the data of peak period , It can be seen from the peak data table that in the morning 9 Point to 10 00 p.m 14 Point to 15 Point is the advanced time period , Calculate according to ten o'clock in the morning . It can be seen from the data in the table ,10 At the time of the PV The number of 1300+2706+526+676=5208PV, that TPS=5208PV÷3600s≈1.45, The result of this calculation is an approximate value , Generally speaking, if you can get the business volume per minute, it will be more accurate , Usually when calculating TPS When using 28 principle （ The box 20% Time to finish 80% The business of ） So another better calculation method is the following table ：
  
• Number of concurrent users ： Commonly used Method of calculating concurrency 1） from TPS Count to estimate concurrency ;2） The number of concurrent users is estimated by the number of online users ;3） Estimate the number of concurrent users based on experience ;
  Use... In most cases ： Number of concurrent users =TPS (Runtime+Thinktime) among Thinktime by 3;Runtime It is the time required for the test program to run once ;
  The number of concurrent users of this forum system is estimated to be 76=5.813; Select the number of concurrent users for each service as shown in the following table ：
  
  PS：
  The average number of concurrent users is as follows
  1） The average number of concurrent users is C = nL/T
  2） Peak number of concurrent users C‘ = C + 3* Radical sign C
  C Is the average number of concurrent users ,n yes login session The number of ,L yes login session Average length of ,T It's the length of time worth examining ;C’ Is the peak number of concurrent users
  Use... In most cases ： Number of concurrent users =TPS *(Runtime+Thinktime) among Thinktime by 3;Runtime It is the time required for the test program to run once ; Or there's another one Runtime、Thinktime Classified as response time