Name

ngx_http_upstream_iwrr_module.

Introduction

The IWRR module is an efficient load balancing algorithm with O(1) time complexity, but IWRR is no need to incremental initialization.

Compared with Nginx's official SWRR algorithm and VNSWRR, IWRR abandons smoothness on the premise of ensuring the correctness of the weighted load balancing algorithm, ensuring that no matter how the total weight of the cluster changes, IWRR space The complexity is always O(n).

Example

http {

    upstream backend {
        iwrr; # enable IWRR load balancing algorithm.
        127.0.0.1 port=81;
        127.0.0.1 port=82 weight=2;
        127.0.0.1 port=83;
        127.0.0.1 port=84 backup;
        127.0.0.1 port=85 down;
    }
    
    server {
        server_name localhost;
        
        location / {
            proxy_pass http://backend;
        }
    }
}

Installation

Build Tengine with this module from source:

./configure --add-module=./modules/ngx_http_upstream_iwrr_module/
make
make install

Directive

iwrr

Syntax: iwrr [max_init=number]
Default: none
Context: upstream

Enable iwrr load balancing algorithm.