StackExchange is the most popular and professional IT Q&A site, Under StackExchange, there is StackOverflow and other sub sites. Many of us may wonder how this mega site is maintained and what its performance is. A performance page has been released by StackExchange recently.
Below is some statistic about this mega site.
- 560 million page views per month, i.e around 1.9 million PVs per day.
- For such as big site, it has only 9 web servers and 4 SQL servers(while two of them are in backup mode)
- 185 requests per second, 559 million SQL queries per day with peak rate at 10,700 queries/sec
- Two redis server: one master and one slave. 3.65 billion operations per day
- Stackoverflow created a famous tag system which can add tags to the questions or answers posted on the system. Hence it dedicates three separate tag engines to process all the tagged contents.
- 3 elasticsearch server, these servers provide the index and search capability on Stackoverflow. They handle 42 million searched per day
- 2 HAPROXY servers These two are deployed for load balancing.
- At any time, there are 260,000 socket connections sustained in average
- Programming stack include : C# + ASP.net MVC, Dapper ORM, StackExchange Redis, DotNetOpenAuth, MiniProfiler and JIL.
With all the effort StackExchange has put, the access time to its home page is only 52 ms and the access time to its question page is only 33 ms.
