Hi:
We improve the Smooth Weighted Round-Robin（SWRR） algorithm to successfully
resolve the problem in the following situations.
Situation 1：
upstream backend-server {
server 1.1.1.1:8000 weight=100;
server 2.2.2.2:8000 weight=101;
server 3.3.3.3:8000 weight=100;
}
1. When each machine in the cluster mode executes "-s reload" at the same time
, the first selection of each machine is the machine 2.2.2.2:8000 having higher
weight , which will lead to 300%+ increase of 2.2.2.2:8000 traffic.
2. More and more companies are implementing service discovery based on nginx.
Adding or removing machine will also lead to 300%+ increase of 2.2.2.2:8000
traffic.
Situation 2：
upstream backend-server {
server 1.1.1.1:8000 weight=100;
server 2.2.2.2:8000 weight=100;
server 3.3.3.3:8000 weight=100;
}
1. When each machine in the cluster mode executes "-s reload" at the same time
, the first selection of each machine is the first machine 1.1.1.1:8000, which
will lead to 300%+ increase of 1.1.1.1:8000 traffic.
2. More and more companies are implementing service discovery based on nginx.
Adding or removing machine will also lead to 300%+ increase of 1.1.1.1:8000
traffic.
# HG changeset patch
# User Jie Chen
<[email protected]<mailto:[email protected]>>
# Date 1599813602 -28800
# Fri Sep 11 16:40:02 2020 +0800
# Node ID 931b0c055626657d68f886781c193ffb09245a2e
# Parent da5e3f5b16733167142b599b6af3ce9469a07d52
improve the first selection of SWRR algorithm
diff -r da5e3f5b1673 -r 931b0c055626 src/http/ngx_http_upstream_round_robin.c
--- a/src/http/ngx_http_upstream_round_robin.c Wed Sep 02 23:13:36 2020 +0300
+++ b/src/http/ngx_http_upstream_round_robin.c Fri Sep 11 16:40:02 2020 +0800
@@ -91,7 +91,7 @@
peer[n].name = server[i].addrs[j].name;
peer[n].weight = server[i].weight;
peer[n].effective_weight = server[i].weight;
- peer[n].current_weight = 0;
+ peer[n].current_weight = 0 - ngx_random() %
peers->total_weight;
peer[n].max_conns = server[i].max_conns;
peer[n].max_fails = server[i].max_fails;
peer[n].fail_timeout = server[i].fail_timeout;
@@ -155,7 +155,7 @@
peer[n].name = server[i].addrs[j].name;
peer[n].weight = server[i].weight;
peer[n].effective_weight = server[i].weight;
- peer[n].current_weight = 0;
+ peer[n].current_weight = 0 - ngx_random() %
peers->total_weight;
peer[n].max_conns = server[i].max_conns;
peer[n].max_fails = server[i].max_fails;
peer[n].fail_timeout = server[i].fail_timeout;
Thanks~
[email protected]<mailto:[email protected]>
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