Redis learning talks about the single-threaded reactor model
This article will talk about the single-threaded reactor model, I/O model, and multi-threaded I/O model in Redis. I hope it will be helpful to you!
High performance of redis
- Pure memory access, all data is in memory, and all operations are For memory-level operations, the memory response time is at the nanosecond level. Therefore, the CPU of the redis process basically does not have disk I/O waiting time and memory read and write performance problems. The CPU is not the bottleneck of redis (memory size and network I/O are the bottleneck of redis, that is, the gap between the client and the server. network transmission delay). [Related recommendations: Redis Video Tutorial]
- adopts a single-thread model, and single-thread implementation is simple. Avoids the overhead caused by frequent context switching of multiple threads and synchronization mechanisms such as locks
- Simple and efficient basic data structures: dynamic strings (SDS), linked lists, dictionaries, jump linked lists, integer sets and compressed lists. Then redis uses this basis to implement objects that users can operate: strings, lists, hashes, sets, ordered sets and other objects
- reactor mode network event processor. It uses I/O multiplexing to monitor multiple sockets at the same time, which is an efficient I/O model. For reactor-related knowledge, you can read this articleFramework: See the Linux high-performance network IO Reactor model
Why use single thread
- Uses a single thread to avoid unnecessary context switching and competition conditions; there is no switching caused by multiple threads that consumes the CPU
- There is no need to consider various lock issues, and there is no locking and releasing There is no performance consumption due to possible deadlocks in lock operations. It is simple and maintainable. Multi-thread mode will make program writing more complex and troublesome. Single-thread implementation is easy to implement.
We often say that redis is single-threaded because its network event processing model reactor is single-threaded
- If a client request deletes millions of key values, then this The command may cause blocking. In redis 4.0, we chose to introduce multi-threading to implement this type of non-blocking commands
- In the redis6.0 version, multi-threading was officially introduced to process the client's I/O read and write responses, while the processing of redis command events is still in Main thread single-line processing
- If it is for the entire redis system, there will always be other threads to process asynchronous tasks, such as AOF and RDB synchronization
redis is fast in processing, not only because it is a single-threaded pure memory system, but also because it adopts the Reactor model and uses I/O multiplexing to process external requests. , Reduce network connection, read and write waiting time. Enable it to handle a large number of client requests concurrently in network I/O operations, achieving high throughput and high concurrency
For more programming-related knowledge, please visit:
The above is the detailed content of Redis learning talks about the single-threaded reactor model. For more information, please follow other related articles on the PHP Chinese website!

Redis is a powerful database solution because it provides fast performance, rich data structures, high availability and scalability, persistence capabilities, and a wide range of ecosystem support. 1) Extremely fast performance: Redis's data is stored in memory and has extremely fast read and write speeds, suitable for high concurrency and low latency applications. 2) Rich data structure: supports multiple data types, such as lists, collections, etc., which are suitable for a variety of scenarios. 3) High availability and scalability: supports master-slave replication and cluster mode to achieve high availability and horizontal scalability. 4) Persistence and data security: Data persistence is achieved through RDB and AOF to ensure data integrity and reliability. 5) Wide ecosystem and community support: with a huge ecosystem and active community,

Key features of Redis include speed, flexibility and rich data structure support. 1) Speed: Redis is an in-memory database, and read and write operations are almost instantaneous, suitable for cache and session management. 2) Flexibility: Supports multiple data structures, such as strings, lists, collections, etc., which are suitable for complex data processing. 3) Data structure support: provides strings, lists, collections, hash tables, etc., which are suitable for different business needs.

The core function of Redis is a high-performance in-memory data storage and processing system. 1) High-speed data access: Redis stores data in memory and provides microsecond-level read and write speed. 2) Rich data structure: supports strings, lists, collections, etc., and adapts to a variety of application scenarios. 3) Persistence: Persist data to disk through RDB and AOF. 4) Publish subscription: Can be used in message queues or real-time communication systems.

Redis supports a variety of data structures, including: 1. String, suitable for storing single-value data; 2. List, suitable for queues and stacks; 3. Set, used for storing non-duplicate data; 4. Ordered Set, suitable for ranking lists and priority queues; 5. Hash table, suitable for storing object or structured data.

Redis counter is a mechanism that uses Redis key-value pair storage to implement counting operations, including the following steps: creating counter keys, increasing counts, decreasing counts, resetting counts, and obtaining counts. The advantages of Redis counters include fast speed, high concurrency, durability and simplicity and ease of use. It can be used in scenarios such as user access counting, real-time metric tracking, game scores and rankings, and order processing counting.

Use the Redis command line tool (redis-cli) to manage and operate Redis through the following steps: Connect to the server, specify the address and port. Send commands to the server using the command name and parameters. Use the HELP command to view help information for a specific command. Use the QUIT command to exit the command line tool.

Redis cluster mode deploys Redis instances to multiple servers through sharding, improving scalability and availability. The construction steps are as follows: Create odd Redis instances with different ports; Create 3 sentinel instances, monitor Redis instances and failover; configure sentinel configuration files, add monitoring Redis instance information and failover settings; configure Redis instance configuration files, enable cluster mode and specify the cluster information file path; create nodes.conf file, containing information of each Redis instance; start the cluster, execute the create command to create a cluster and specify the number of replicas; log in to the cluster to execute the CLUSTER INFO command to verify the cluster status; make

To read a queue from Redis, you need to get the queue name, read the elements using the LPOP command, and process the empty queue. The specific steps are as follows: Get the queue name: name it with the prefix of "queue:" such as "queue:my-queue". Use the LPOP command: Eject the element from the head of the queue and return its value, such as LPOP queue:my-queue. Processing empty queues: If the queue is empty, LPOP returns nil, and you can check whether the queue exists before reading the element.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SublimeText3 Linux new version
SublimeText3 Linux latest version

SublimeText3 Mac version
God-level code editing software (SublimeText3)

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function