After class assignment of module 5 of the construction practice camp

Homework

Design microblog system ” Weibo comments “ High performance and high availability computing architecture .

【 Job requirements 】

Based on modules 5 The first 6 Practical cases of microblog in class , analysis “ Weibo comments ” The business features of this core scenario , Then design its high-performance and high availability computing architecture , Including but not limited to the following ：

1.  Computational performance prediction （ There is no need to consider storage performance ）;

2.  High performance computing architecture for non hot events , You need to consider whether to split separate services ;

3.  High availability computing architecture for hot events .

【 Tips 】

1.  Comparison of analytical methods “ Look at micro-blog ” and “ Micro-blog ” The case of .

 

answer

1.      Weibo comment user behavior modeling and performance estimation

  Combined with the estimation of Weibo , Suppose the average number of people watching a microblog is 100 Time , The number of times you watch microblog is ：2.5 Billion  * 100 = 250 Billion .

After reading the microblog, the number of people who can make comments is the number of people who read the microblog 1/5, The number of comments on microblog is  2.5 Billion  * 100 *1/5= 50 Billion

Most people watch microblog for the same time period as they comment on microblog , So the average number of comments on Weibo  TPS  The calculation is as follows ：

50 Billion  * 60% / (4*3600) = 20K/s.

2. High performance computing architecture for non hot events , You need to consider whether to split separate services

【 Business characteristic analysis 】

Commenting on Weibo is also a writing operation , So you can't use cache , Load balancing can be used .

【 Architecture analysis 】

Over 100 million users , You should use a multi-level load balancing architecture , Cover  DNS -> F5 -> Nginx ->  Multilevel load balancing of gateway .

【 Architecture design 】

1.  Load balancing algorithm selection

When commenting on Weibo, it depends on login status , The login status is generally saved in the distributed cache , So when commenting on Weibo , Send the request to any server , Choose here “ polling ” perhaps “ Random ” Algorithm .

2.  Estimate the number of business servers

Commenting on microblogging involves several key processes ： Content review （ Rely on the audit system ）、 Write data to storage （ Dependent on storage system ）、 Data write cache （ Rely on the cache system ）, So, per service per second 500 To estimate , complete 20K/s Of  TPS, need 40 Servers , Plus a certain amount of reserve ,50 This server is almost .

【 Comment on the multi-level load balancing architecture of microblog 】

 

3. High availability computing architecture for hot events .

【 Comment on Weibo 】

It's hard to predict , It is related to the influence and scope of hot events .

【 Business characteristic analysis 】

After the hot event , Most of the requests fell on the microblog that led to the hot event

【 Architecture design analysis 】

Obviously , There is a cache hotspot problem in the hot event microblog , If it is “ Multi copy cache ”, And the original cache architecture has been adopted “ Cache in application , In general , Cache hot issues are not necessarily prominent , Such comments on Weibo are not necessarily prominent .

【 Schematic diagram of hot event high availability architecture 】