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How to use Redis to implement distributed locks in SpringBoot

1. Redis implements distributed lock principle and why distributed locks are needed. Before talking about distributed locks, it is necessary to explain why distributed locks are needed. The opposite of distributed locks is stand-alone locks. When we write multi-threaded programs, we avoid data problems caused by operating a shared variable at the same time. We usually use a lock to mutually exclude the shared variables to ensure the correctness of the shared variables. Its scope of use is in the same process. If there are multiple processes that need to operate a shared resource at the same time, how can they be mutually exclusive? Today's business applications are usually microservice architecture, which also means that one application will deploy multiple processes. If multiple processes need to modify the same row of records in MySQL, in order to avoid dirty data caused by out-of-order operations, distribution needs to be introduced at this time. The style is locked. Want to achieve points

Jun 03, 2023 am 08:16 AM

redisSpringBoot

How to build a redis replication cluster

Environment preparation 1. Server (or cloud server) based on centos7 system; 2. Due to resource limitations, this article will be built on a server and distinguished by different port numbers; 2. Upload the redis installation package Go to the specified directory (and decompress) 2. In the current directory, create three directories. Create three file directories 7001, 7002, and 7003 respectively. 3. Copy the redis.conf configuration file under the redis decompression package to 4. Modify the default port number of each configuration file in the three directories. The data storage directory can be replaced and modified in batches using the sed command sed-i-e's/6379/7001/

Jun 03, 2023 am 08:03 AM

redis

How to implement Redis distributed cache and flash sales

1. Problems with single-point Redis 1. Data loss problem Redis data persistence. 2. For concurrency issues, we use master-slave clusters to achieve separation of reading and writing. 3. Fault recovery issues use Redis Sentinel to implement health detection and automatic recovery. 4. For storage capacity issues, build a sharded cluster and use the slot mechanism to achieve dynamic expansion. 2. The full name of RDBRDB is RedisDatabaseBackupfile (Redis data backup file), also called Redis data snapshot. To put it simply, all the data in the memory is recorded to the disk. When the Redis instance fails and restarts, the snapshot file is read from the disk and the data is restored. The snapshot file is called an RDB file and is saved in the current running directory by default. R

Jun 02, 2023 pm 11:43 PM

redis

How to set up php environment redis

1. Download 1. Download http://download.redis.io/releases/redis-6.0.9.tar.gz locally, transfer the file and upload it to /usr/local/src/2, wget-P/usr/local /src/http://download.redis.io/releases/redis-6.0.9.tar.gz 2. Unzip, compile, and install>cd/usr/local/src>tarxzftarxzfredis-6.0.9.tar.gz> cdredis-6.0.9>make

Jun 02, 2023 pm 11:25 PM

PHPredis

How Springboot implements Redis distributed reentrant lock source code analysis based on Redisson

1. Introduction We are using Redis to implement distributed locks. At first, we generally use SETresource-nameanystringNXEXmax-lock-time to lock, and use Lua scripts to ensure atomicity to release the lock. This manual implementation is more troublesome. The Redis official website also clearly states that the Java version uses Redisson to implement it. The editor also looked at the official website and slowly figured it out, and took a close-up to record it. From the official website to integrating Springboot to source code interpretation, take a single node as an example. 2. Why use Redisson1. We open the official website redis Chinese official website 2. We can see that the official website allows us to use other 3. Open the official push

Jun 02, 2023 pm 11:21 PM

redisSpringBootredisson

How to catch redis exception in Python

Python captures the redis exception scenario and reproduces it. Using python's redis package to connect to redis, the wrong password was deliberately set, but it was found that it did not cause an exception. Environment system: win10 python version: 3.6.8 Initial code importredishost="127.0.0.1" port=6379password ="123456"redis_conn=redis.Redis(host=host,port=port,password) After testing, we found that after creating the connection object, we use the conn object to

Jun 02, 2023 pm 11:14 PM

Pythonredis

How SpringBoot integrates Redis

The architectural solution uses redis for centralized storage to realize distributed cluster sharing of user information. Here we use the third-party open source plug-in crazycake to implement it. The pom.xml introduces: org.springframework.bootspring-boot-starter-data-redisorg.crazycakeshiro-redis3.2.3 Configure application.properties: #Redis#Database index (default is 0) redis.database=0#Change the server address to your own redis.host=127.0.0.1#Server connection port re

Jun 02, 2023 pm 11:07 PM

redisSpringBoot

How to apply Redis keys and common database instructions

1. Redis key (key) general instruction key characteristics: key is a string, and the data saved in redis is obtained through key. 1. Key basic operation command function delkey This command is used to delete keyexistskey when the key exists. Check whether the given key exists. Typekey returns the type of the value stored in the key. Demonstration results: 2. Timeliness control command function EXPIREkeyseconds sets expiration for the given key. Time, in seconds PEXPIRE keymilliseconds Set the expiration time of the key in milliseconds EXPIREAT keytimestamp The role of EXPIREAT and EXPIRE

Jun 02, 2023 pm 10:43 PM

redis

How to use Lua script in Java ecosystem/Redis

1. Install LUA Installing LUA on Mac is very simple. Just use brew related commands directly; brewinstalllua uses the lua-v command to see that lua has been installed. 1) Simple use to create a test.lua file, the content is: Execute command: luatest.lua output is: 2. Introduction to lua syntax Lua provides interactive programming and scripted programming: Interactive programming: directly enter the syntax on the command line , you can execute it immediately and see the execution effect. Scripting is programming: write a script file and then execute it. 1. Comment Lua provides two comment methods: single-line comments and multi-line comments 1) Single-line comments use two minus signs;--2) Multi-line comments--[[Multi-line comments multi-line

Jun 02, 2023 pm 10:41 PM

Javaredislua

Example analysis of high availability in Redis sentry mode

1. Preface There are two modes of Redis high availability: sentry mode and cluster mode. This article builds a one-master, two-slave and three-sentinel Redis high-availability service based on the sentinel mode. 1. Goals and gains: One master, two slaves and three sentry Redis services can basically meet the high availability requirements of small and medium-sized projects. Supervisor is used to monitor and manage Redis instances. Through this article, we will achieve the following goals: Sentinel mode service planning and construction Sentinel mode services are more reliable than stand-alone services, and are suitable for scenarios where read and write are separated, the amount of data is not large, and reliability and stability are required. Client integration and read-write separation connect to Sentinel mode through the Spring framework to complete common operations in the production environment. 2. Port planning Port planning is the first step in completing this solution.

Jun 02, 2023 pm 10:38 PM

redis

What is the principle of Redis's common current limiting algorithm and how to implement it

Introduction Current limiting, referred to as traffic rate limiting (RateLimit), means that only specified events are allowed to enter the system, and the excess will be denied service, queued or waited for, downgraded, etc. Common current limiting schemes are as follows: Fixed time window Fixed time window is One of the most common current limiting algorithms. The concept of window corresponds to the current limiting time unit in the current limiting scenario. The principle timeline is divided into multiple independent and fixed-size windows; requests falling within each time window will increase the counter by 1; if the counter exceeds the current limiting threshold, subsequent requests falling within this window will be rejected. But when the time reaches the next time window, the counter will be reset to 0. Example description: As shown in the above scene, the flow is limited to 10 times per second, the window size is 1 second, and each square represents

Jun 02, 2023 pm 10:37 PM

redis

What are the methods to start redis in Linux?

1. Start directly into the redis root directory and execute the command: #Add the '&' sign to make redis run as a background program nohupredis-server& 2. Start by specifying the configuration file to start the specified configuration file for the redis service, for example, configure it as /etc/ redis/6379.conf Enter the redis root directory and enter the command: ./redis-server/etc/redis/6379.conf #If the port is changed, you also need to specify the port when using the redis-cli client to connect, for example: redis- cli-p63803

Jun 02, 2023 pm 10:33 PM

Linuxredis

What is the use of reading and writing separation in Redis?

Read-write separation Redis implements the "master-slave" operating mode through copies, which is the cornerstone of failover and is used to improve system operation reliability. It also supports read and write separation to improve read performance. You can deploy one master node and multiple slave nodes. Distribute read commands to slave nodes to reduce pressure on the master node and improve performance.

Jun 02, 2023 pm 10:33 PM

redis

How to install and configure redis database under Ubuntu

1. Log in with root privileges 2. Next enter the command, apt-getinstallredis-server, as shown in the figure: 3. After the installation is completed, the redis server will start automatically. We check the redis server program and execute ps-aux|grepredis, as shown in the figure: 4. Check the redis server status through the startup command, execute: netstat-nlt|grep6379, as shown in the figure: 5. Install the redis server, and the redis command line client program will be automatically installed together. Enter the redis-cli command on this machine to start, and the client program accesses the redis server. Execute: redis-cli, as shown in Figure: 6. Go to

Jun 02, 2023 pm 10:28 PM

Ubunturedis