What are the load balancing algorithms of nginx?

Load balancing scheduling algorithm supported by Nginx

1.round robin (default) (recommended learning: nginx tutorial)

Polling method, which distributes requests to each background server in turn, is the default load balancing method.

Applicable to situations where the background machine performance is consistent.

Hanged machines can be automatically removed from the service list.

2.weight

Distribute requests to different machines according to weight, specify polling probability, weight is proportional to access ratio, used for back-end server performance uneven situation.

For example:

upstream bakend {    
server 192.168.0.14 weight=10;    
server 192.168.0.15 weight=10;    
}

3. IP_hash

Send the request to the backend server based on the hash value of the requester’s IP, which can ensure that it comes from the same IP The request is sent to a fixed machine, which can solve the session problem.

For example:

upstream bakend {    
ip_hash;    
server 192.168.0.14:88;    
server 192.168.0.15:80;    
}

4.url_hash (third party)

Divide the request into different machines according to the hash value of the requested url. It is efficient when the background server is cached.

For example:

Add a hash statement to the upstream. Other parameters such as weight cannot be written in the server statement. Hash_method is the hash algorithm used

upstream backend {    
server squid1:3128;    
server squid2:3128;    
hash $request_uri;    
hash_method crc32;    
}

tips:

upstream bakend{#Define the IP and device status of the load balancing device

ip_hash;    
server 127.0.0.1:9090 down;    
server 127.0.0.1:8080 weight=2;    
server 127.0.0.1:6060;    
server 127.0.0.1:7070 backup; 
}

Add to the server that needs to use load balancing

proxy_pass http://bakend/;

The status of each device is set to:

1.down means that the previous server will not participate in the load temporarily

2.weight The default is 1. The larger the weight, the greater the weight of the load.

3.max_fails: The number of allowed request failures is 1 by default. When the maximum number is exceeded, the error defined by the proxy_next_upstream module is returned.

4.fail_timeout: The pause time after max_fails failures.

5.backup: When all other non-backup machines are down or busy, request the backup machine. So this machine will have the least pressure.

nginx supports setting up multiple groups of load balancing at the same time for use by unused servers.

client_body_in_file_only Set to On, the data from the client post can be recorded to a file for debugging

client_body_temp_path Set the directory of the recording file to set up to 3 levels of directories

location Match the URL. You can redirect or perform new proxy load balancing

5. fair (third party)

Distribute requests and responses based on the background response time A shorter distribution time will result in more requests.

For example:

upstream backend {    
server server1;    
server server2;    
fair;    
}

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