In-depth understanding of Nginx's load balancing algorithm and strategy selection method

In-depth understanding of Nginx's load balancing algorithm and policy selection method

1. Introduction

With the rapid development of the Internet and the popularization of applications, high concurrent access has become the web One of the important issues in application. Load balancing technology is one of the keys to solving the problem of high concurrent access. As a high-performance web server and reverse proxy server, Nginx is favored by developers for its load balancing function. This article will delve into Nginx's load balancing algorithm and strategy selection method.

2. Nginx load balancing algorithm

2.1 Round Robin

Round Robin is the default load balancing algorithm of Nginx. It distributes requests to backend servers in order, keeping the load on each server relatively balanced. When a new request arrives, Nginx will forward the request to each server in sequence in the order of the server list in the upstream defined in advance.

The sample code is as follows:

upstream backend {
    server 192.168.1.101;
    server 192.168.1.102;
    server 192.168.1.103;
}

server {
    location / {
        proxy_pass http://backend;
    }
}

2.2 Weighted Round Robin

Weighted polling is based on the polling algorithm, allocating a Weight value, the higher the weight, the greater the probability of being assigned to the request. In this way, requests can be reasonably distributed based on the performance and load of the server.

The sample code is as follows:

upstream backend {
    server 192.168.1.101 weight=3;
    server 192.168.1.102 weight=2;
    server 192.168.1.103 weight=1;
}

server {
    location / {
        proxy_pass http://backend;
    }
}

2.3 IP Hash

The IP Hash algorithm performs hash calculation based on the requested client IP address, and then forwards the request to the corresponding server. This allows requests from the same IP address to be forwarded to the same server to achieve session persistence.

The sample code is as follows:

upstream backend {
    ip_hash;
    server 192.168.1.101;
    server 192.168.1.102;
    server 192.168.1.103;
}

server {
    location / {
        proxy_pass http://backend;
    }
}

3. Strategy selection method

3.1 Static configuration

Static configuration is the most common strategy selection method , that is, by manually configuring the server list and weight value in upstream to implement the corresponding load balancing algorithm. This method is suitable for situations where the server size is relatively stable and the load is relatively balanced.

3.2 Dynamic configuration

Dynamic configuration is to dynamically adjust the load balancing algorithm and policy selection based on the actual server load during operation. Nginx provides some related modules, such as nginx-plus-upsync and nginx-upsync-module, which can regularly check the status of the back-end server and automatically adjust the weight value, add, delete and modify the back-end server to achieve dynamic load balancing .

The sample code is as follows:

upstream backend {
    zone backend 64k;
    server 192.168.1.101;
    server 192.168.1.102;
    server 192.168.1.103;
    keepalive 64;
    hash $remote_addr consistent;
}

server {
    location / {
        proxy_pass http://backend;
    }
}

4. Conclusion

This article provides an in-depth understanding of Nginx’s load balancing algorithm and strategy selection method. In actual development, selecting appropriate load balancing algorithms and policy selection methods based on actual needs can effectively improve application performance and reliability. At the same time, understanding the dynamic configuration method can dynamically adjust the load balancing strategy according to the server load, further improving the stability and scalability of the application.

Reference:

1. Nginx Documentation - http://nginx.org/en/docs/
2. Nginx Load Balancing - http://nginx.org /en/docs/http/load_balancing.html

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