nginx 内容下载和 TTFB 非常慢

Question

我使用 Nginx 就像使用 cdn 一样。
我的服务器在 hetzner 上保证 1 Gbit 带宽。Intel Xeon E5-1650 v2 Hexa Core 128 GB DDR3 ECC 2× 240 GB SATA3 数据中心系列 SSD。平均负载为 0.04。可用内存 116gb。ubuntu 服务器 16.04.3 LTS。nginx 版本：nginx/1.13.8

我不明白为什么 nginx http2 很慢。请查看屏幕截图：https://vgy.me/75FMVO.jpg

stub_status

Active connections: 1020 
server accepts handled requests
1733491 1733491 19208056 
Reading: 0 Writing: 275 Waiting: 741 

这是我的服务器配置

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    listen 443 ssl default_server http2;
    listen [::]:443 ssl default_server http2;

    set $cors '';
    if ($http_origin ~ '^https?://(localhost|www\.example\.com|www\.example2\.com)') {
            set $cors 'true';
    }
    server_name  cdn.example.com;
    #ssl on;
    ssl_certificate /etc/nginx/ssl/cdn_example_com_bundle.crt;
    ssl_certificate_key /etc/nginx/ssl/cdn_example_com.key;
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

    ssl_session_cache shared:SSL:20m;
    ssl_session_timeout 60m;
    ssl_prefer_server_ciphers on;
    ssl_dhparam /etc/nginx/ssl/dhparam.pem;
    ssl_ciphers  EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH:EDH+aRSA:HIGH:!aNULL:!eNULL:!LOW:!RC4:!3DES:!MD5:!EXP:!PSK:!SRP:!SEED:!DSS:!CAMELLIA;
    ssl_stapling on;
    ssl_stapling_verify on;
    #ssl_trusted_certificate /etc/nginx/ssl/cdn_example_com_bundle.crt;
    resolver 8.8.8.8 8.8.4.4;

    index /index.html;
    error_page  404  /index.html;

    location ~* \.(gif|jpg|jpeg|png|js|css|pdf|woff|ttf|woff2|eot|svg)$ {
        if ($cors = 'true') {
                add_header 'Access-Control-Allow-Origin' "$http_origin" always;
                add_header 'Access-Control-Allow-Credentials' 'true' always;
                add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS' always;
                add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Requested-With' always;
                add_header 'Strict-Transport-Security' 'max-age=31536000' always;

                # required to be able to read Authorization header in frontend
                #add_header 'Access-Control-Expose-Headers' 'Authorization' always;
        }

        if ($request_method = 'OPTIONS') {
                # Tell client that this pre-flight info is valid for 20 days
                add_header 'Access-Control-Max-Age' 1728000;
                add_header 'Content-Type' 'text/plain charset=UTF-8';
                add_header 'Content-Length' 0;
                return 204;
        }
        expires max;
        root /var/www/html;
        try_files $uri $uri/ @s3;
    }

    location @s3 {
        expires max;
        proxy_set_header  X-Real-IP  $remote_addr;
        proxy_pass http://www.example.com;
        proxy_ignore_headers X-Accel-Expires Expires Cache-Control;
        proxy_store /var/www/html$uri;
        proxy_store_access user:rw group:rw all:r;
    }
}

nginx.conf

    user www-data;
    worker_processes auto;
    worker_rlimit_nofile 100000;
    pid /run/nginx.pid;

    events {
        worker_connections 4000;
        use epoll;
        multi_accept on;
    }

    http {

        ##
        # Basic Settings
        ##

        sendfile on;
        tcp_nopush on;
        tcp_nodelay on;
        keepalive_timeout 30;
        types_hash_max_size 2048;
        # server_tokens off;

        # server_names_hash_bucket_size 64;
        # server_name_in_redirect off;

        include /etc/nginx/mime.types;
        default_type application/octet-stream;

        ##
        # SSL Settings
        ##

        ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
        ssl_prefer_server_ciphers on;

        ##
        # Logging Settings
        ##

        #access_log /var/log/nginx/access.log;
        access_log off;
        error_log /var/log/nginx/error.log;

        ##
        # Gzip Settings
        ##

        gzip on;
        gzip_disable "msie6";

        # gzip_vary on;
        # gzip_proxied any;
        # gzip_comp_level 6;
        # gzip_buffers 16 8k;
        # gzip_http_version 1.1;
        # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

        ##
        # Virtual Host Configs
        ##

        include /etc/nginx/conf.d/*.conf;
        include /etc/nginx/sites-enabled/*;
    }