Nginx请求限流未按预期生效的问题求助

我正在尝试给Nginx配置请求限流，但实际效果和预期不符。我分别测试了每秒2次和每秒10次的限流规则，具体测试过程和结果如下：

测试1：限流规则为每秒2次请求（rate=2r/s） #

Nginx配置 #

limit_req_zone $binary_remote_addr zone=myzone:10m rate=2r/s;
limit_req_status 429;

server {
    listen *:80;
    server_name 172.23.97.94;
    root /var/www/html;
    index index.html;

    location / {
        limit_req zone=myzone;
        try_files $uri $uri/ =404;
    }
}

无间隔请求测试 #

执行以下测试命令：

for i in {1..2}; do curl -I -s "http://172.23.97.94" | head -n 1; done

测试结果：

HTTP/1.1 200 OK
HTTP/1.1 429 Too Many Requests

查看access.log可以看到两个请求是同一时间发送的，但第二个请求返回了429：

172.23.106.65 - - [08/Feb/2023:17:10:35 +0000] "HEAD / HTTP/1.1" 200 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:10:35 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"

加间隔请求测试 #

如果给每个请求之间加0.5秒的间隔，两个请求都返回200：

for i in {1..2}; do curl -I -s "http://172.23.97.94" | head -n 1; sleep 0.5; done

测试结果：

HTTP/1.1 200 OK
HTTP/1.1 200 OK

测试2：限流规则为每秒10次请求（rate=10r/s） #

Nginx配置 #

limit_req_zone $binary_remote_addr zone=myzone:10m rate=10r/s;
limit_req_status 429;

server {
    listen *:80;
    server_name 172.23.97.94;
    root /var/www/html;
    index index.html;

    location / {
        limit_req zone=myzone;
        try_files $uri $uri/ =404;
    }
}

无间隔请求测试 #

执行以下测试命令：

for i in {1..10}; do curl -I -s "http://172.23.97.94" | head -n 1; done

测试结果：

HTTP/1.1 200 OK
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests

查看access.log可以看到10个请求是同一时间发送的，但只有第一个请求返回200：

172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 200 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"
172.23.106.65 - - [08/Feb/2023:17:14:53 +0000] "HEAD / HTTP/1.1" 429 0 "-" "curl/7.68.0"

加间隔请求测试 #

如果给每个请求之间加0.01秒的间隔，部分请求返回200，其余返回429：

for i in {1..10}; do curl -I -s "http://172.23.97.94/device/1" | head -n 1; sleep 0.01; done

测试结果：

HTTP/1.1 200 OK
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 200 OK
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 429 Too Many Requests
HTTP/1.1 200 OK

我是不是哪里配置出错了？还是Nginx的限流功能本身就不是我理解的这样工作的？

备注：内容来源于stack exchange，提问作者catalin