Redis02: install redis in Linux Environment

1、 Installation steps

First step ： download Redis Installation package

The second step ： Use Xftp Tool upload redis-5.0.7.tar.gz To linux System .

The third step ： decompression redis-5.0.2.tar.gz To /opt Catalog

Step four ： compile redis, Go to unzip directory

Step five ： Basic environment installation （ install gcc）

yum install gcc-c++

What is? gcc ?

gcc yes GNU compiler collection Abbreviation , It is Linux The next compiler collection ( amount to javac ), yes c or c++ The compiler of the program .

Step six ： perform make Command to compile

Step seven ： perform make install install redis

Be careful ： stay make Execute after execution make install, This action will src Many of the executable files under are copied to /usr/local/bin Under the table of contents , This can be done in any directory redis The command of the software （ For example, start , stop it , And so on ）, make install You don't have to execute , Personal habits .

see make Compilation result ,cd src Catalog

Step eight ： take redis Copy the configuration file to our current directory

Step nine ：redis It is not started in the background by default , You need to modify the configuration file to ensure background startup

[[email protected] hconfig]# vim redis.conf 

Step 10 ： start-up Redis service

[[email protected] bin]# redis-server hconfig/redis.conf 

Step 11 ： Use redis The client connects

[[email protected] bin]# redis-cli -p 6379

The twelfth step ： see redis Whether the process of

[[email protected] ~]$ ps -ef|grep redis

Thirteenth Step ： close redis service

① Use redis Client shutdown , Issue a shutdown command to the server

Single instance close ：redis-cli shutdown

You can also enter the terminal and then close it （ The following is the closing after entering the terminal ）

Multi instance shutdown , The specified port is closed ：redis-cli -p 6379 shutdown

sign out Redis client ：exit perhaps quit Instructions .

This is the recommended way , redis Finish the data operation first , Then turn it off .
for example ：

Check again that the process has closed

②kill pid perhaps kill -9 pid

This method does not consider whether the current application has data in operation , Just close the app .

First use ps -ef | grep redis Find out the process number , Reuse kill pid

2、Redis Basic knowledge

2.1 test Redis performance

Example ：100 Two concurrent connections ,100000 Requests

First of all to enter bin Catalog

[[email protected] ~]$ cd /usr/local/bin

[[email protected] bin]$ redis-benchmark -h localhost -p 6379 -c 100 -n 100000

2.2 Redis Communication command , Check the status

redis >ping 
 return PONG

# explain ： Input ping,redis Come back to us PONG, Express redis The service is running normally 

2.3 see redis Server statistics ：info

 grammar ：info [section]

effect ： In a format that is easy to explain and easy to read , Return to about Redis All kinds of information and statistics of the server .section Used to return the statistics of the specified part . section Value ：server , clients ,memory wait . No addition section Return all statistics

Return value ： Appoint section Statistics or all information about

example 1： Statistics server Information about

example 2： Count all the information

2.4 redis By default 16 Databases

​ Redis By default 16 Databases , from 0 To 15. Modify the number of databases , stay redis.conf In file databases 16, Theoretically, you can configure an unlimited number of .

Redis The library is similar to a database instance in a relational database , But there are some differences , such as redis Each library in cannot be named by user , It can only be expressed by serial number ,redis Each library in is not completely independent , It is best to use one for each application redis example , Not recommended redis Save the data of multiple applications in the instance .Redis The storage space occupied by the instance itself is actually very small , So there is no waste of storage space .

2.5 Switch library commands ：select db

By default, use section 0 individual , If you want to use another database , The order is select index

2.6 View the current database key Number of ：dbsize

# grammar ：dbsize# effect ： Returns the... Of the current database  key  The number of .# Return value ： Numbers ,key The number of 

**2.7 View what is in the current database key：keys ***

2.8 Empty the current library ：flushdb

2.9 Empty all database contents ：flushall

It also shows redis The libraries in are not completely irrelevant .

**2.10 get redis All configuration values for ：config get ***

example 1： Get the number of databases config get databases

example 2： Get the port number config get port

2.11 Redis A single thread + multiple IO Multiplexing technology

Redis yes C language-written , The official data is 100000+ Of QPS, It's no better than using the same key-value Of Memcache Bad

Redis Why is single thread so fast ？

• myth 1： High performance server must be multithreaded ？
• myth 2： Multithreading （CPU Context switch ） It must be more efficient than a single thread ？
• The core ：redis Is to put all the data in memory , Using a single thread to operate the seat is the most efficient , Because multithreading CPU Will be carried out in Context switch , Time consuming operations ！！！ For memory systems , If there is no context switching, the efficiency is the highest , Because many times I read and write in a CPU On , Less time-consuming .

Multiplexing ： It refers to using one thread to check multiple file descriptors （Socket） The ready state of , For example, call select and poll function , Pass in multiple file descriptors , If there is a file descriptor ready , Then return to , Otherwise it blocks until it times out . After getting the ready state, the real operation can be executed in the same thread , You can also start thread execution （ Like using thread pools ）

Serial vs Multithreading + lock （memcached） vs Single thread + multiple IO Reuse (Redis)