Redis's master-slave synchronization and read-write separation mechanism

Redis, as a high-performance in-memory database, faces high concurrency scenarios in daily applications. In order to cope with these needs, Redis provides two mechanisms of master-slave synchronization and read-write separation to improve the performance and availability of Redis. This article will introduce in detail the principle and implementation of Redis's master-slave synchronization and read-write separation.

1. Redis’s master-slave synchronization mechanism

Redis’s master-slave synchronization mechanism can synchronize data from one Redis server to another Redis server to achieve data backup, load balancing, and fault tolerance. Waiting for demand. Among them, one Redis server is the master node, and the other Redis servers are slave nodes. The slave nodes will automatically copy the data of the master node and maintain synchronization with the master node.

1.1 Configuration of the master node

In Redis, if you need to configure a Redis server as the master node, you need to add the following configuration to the Redis configuration file:

# 将当前节点配置为主节点
slaveof no one

After adding this configuration, the Redis server will no longer serve as a slave node, but will become an independent Redis master node.

1.2 Slave node configuration

Starting from Redis version 2.8, Redis has built-in master-slave synchronization mechanism. When the slave node needs to establish a synchronous connection with the master node, you only need to add the following configuration to the Redis configuration file:

# 将当前节点配置为从节点，master_host为主节点IP地址，master_port为端口号
slaveof master_host master_port

In the above configuration, master_host is the IP address of the master node, and master_port is the port number of the master node. , after the slave node completes the configuration, it can automatically synchronize data from the master node.

1.3 The implementation principle of Redis master-slave synchronization

In the Redis master-slave synchronization mechanism, the master node sends the copied data to the slave node, thereby keeping the data of the slave node and the master node consistent. sex. Usually, the workflow of Redis master-slave synchronization is as follows:

1. The master node writes new data into the Redis database and sends the updates to the slave node.
2. After the slave node receives the data transmitted by the master node, it writes the data into its own Redis database.
3. The slave node checks whether the data is successfully written to the Redis database and sends a confirmation message to the master node.
4. After receiving the confirmation message from the slave node, the master node sends the data packet to the connected slave node.
5. After receiving the data packet from the slave node, it writes it into its own Redis database to maintain the consistency of the master-slave data.

2. Redis’s read-write separation mechanism

Redis’s read-write separation mechanism allocates read operations and write operations to different Redis servers to speed up operations. And to improve the availability of Redis server. Normally, read operations occupy less Redis server resources, while write operations place a greater load on the Redis server. Therefore, the use of read-write separation mechanism can effectively alleviate the load of the Redis server and improve the availability of the Redis server.

2.1 Redis read-write separation configuration

Redis implements the read-write separation mechanism, and the way the client accesses the Redis server needs to be modified to support the separation of read and write operations. Under normal circumstances, proxy mode is used to proxy access to Redis, forwarding write operations to the Redis master node and forwarding read operations to the Redis slave node. In this way, the read and write loads of the Redis server can be separated and the performance and availability of Redis can be improved.

2.2 The implementation principle of Redis read-write separation

The Redis read-write separation mechanism realizes the separation of read and write operations by proxying the Redis client. During the implementation process, the proxy mode needs to be used to proxy access to the Redis server, forwarding write operations to the Redis master node, and forwarding read operations to the Redis slave node.

The workflow of Redis read-write separation is as follows:

1. Establish a connection from the Redis client to the proxy server.
2. The Redis client sends the read operation request to the proxy server.
3. The proxy server obtains data from the Redis slave node and returns the data to the Redis client.
4. The Redis client sends the write operation request to the proxy server.
5. The proxy server forwards the data to the Redis master node and checks whether the operation is executed successfully.
6. The Redis master node returns the operation results to the proxy server.
7. The proxy server returns the operation results to the Redis client.

Through the above workflow, the read and write operations of Redis can be separated, thereby improving the performance and availability of the Redis server.

3. Summary

As a high-performance in-memory database, Redis provides two mechanisms of master-slave synchronization and read-write separation to meet high concurrency requirements. Through the master-slave synchronization mechanism, Redis can realize data backup, load balancing, fault tolerance and other functions to improve the availability of Redis. Through the read-write separation mechanism, the read-write load of Redis can be separated to improve the performance of Redis. In actual applications, you can choose according to your needs to achieve the best results.

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