Redis single thread problem forced sorting layman literacy

1. Many people say Redis Single thread performance is very high , Asked about Redis Is it single threaded , Just answer yes . Feel your feet and think , How can one Redis The service is just a thread working . If you don't understand, ask , What's going on
Redis Single thread means Redis Network of IO And the read-write process is completed by a thread , And this wind makes our business most concerned about , That is to say Redis The main process of providing external key value storage , So it is called single thread .
however Redis Other functions of , Data persistence AOF perhaps RDB, Delete data asynchronously , Cluster synchronization data is handled by additional threads .
2.Redis Why can a single thread be so fast ？
The explanation is very simple ,Redis All data of is in memory , Your relational databases are on disk , The reading speed is not an order of magnitude , Do you think he is fast . Another point is that single thread avoids the fatal problem of multithreading , That is online text switching , If it is multithreaded design , My memory reading and writing speed is extremely high , If I read a key value that is 1 nanosecond , As a result, you need to switch between online and offline texts 10 millisecond , Are you sick , I TM Go to the bank to check your deposit , You told me to wait until the manager who opened my account came to check ,30 Mi's knife is beside you , Just ask if you can pull out the knife .
3.Redis How to handle so many concurrent client connections with a single thread ？
Redis Of IO Multiplexing ,Redis utilize epoll To achieve IO Multiplexing , Put the connection information and time in the queue , Then it is handed over to the event distribution processor in turn . Can be in Redis Of redis.config View the maximum number of connections in
command ：config get maxclients