http {
    aio on;  # 啟用異步文件 I/O
    aio_write on;  # 啟用異步寫(xiě)（僅對(duì)支持的文件系統(tǒng)有效）
    
    # 大文件傳輸推薦配置
    sendfile on;  # 啟用零拷貝傳輸
    tcp_nopush on;  # 合并小數(shù)據(jù)包，提高網(wǎng)絡(luò)效率
}

# 創(chuàng)建線程池（處理磁盤 I/O、SSL 等耗時(shí)操作）
thread_pool default threads=32 max_queue=65536;

http {
    # 對(duì)文件操作使用線程池
    aio threads=default;
    
    # 對(duì) SSL 操作使用線程池（高并發(fā) HTTPS 場(chǎng)景）
    ssl_engine device;  # 指定 SSL 硬件加速設(shè)備（如 OpenSSL）
    ssl_threads 4;      # SSL 處理線程數(shù)
}

events {
    use epoll;  # Linux 推薦
    # use kqueue;  # FreeBSD/macOS 推薦
    # use iocp;  # Windows 推薦
    
    worker_connections 65535;  # 每個(gè)工作進(jìn)程支持的最大連接數(shù)
    multi_accept on;  # 一次 accept 多個(gè)連接，提高吞吐量
}

worker_processes auto;  # 根據(jù) CPU 核心數(shù)自動(dòng)調(diào)整

http {
    proxy_connect_timeout 5s;  # 連接后端超時(shí)時(shí)間
    proxy_send_timeout 60s;    # 發(fā)送請(qǐng)求超時(shí)時(shí)間
    proxy_read_timeout 60s;    # 讀取響應(yīng)超時(shí)時(shí)間
    
    proxy_buffer_size 16k;     # 代理響應(yīng)的第一個(gè)緩沖區(qū)大小
    proxy_buffers 4 32k;       # 代理響應(yīng)的緩沖區(qū)數(shù)量和大小
    proxy_busy_buffers_size 64k;  # 繁忙時(shí)的緩沖區(qū)大小
    
    # 對(duì)代理請(qǐng)求啟用異步 I/O
    proxy_request_buffering on;  # 緩沖客戶端請(qǐng)求（默認(rèn) on）
}

upstream backend {
    least_conn;  # 最少連接負(fù)載均衡算法
    
    server backend1.example.com max_fails=3 fail_timeout=30s;
    server backend2.example.com max_fails=3 fail_timeout=30s;
    
    check interval=5000 rise=2 fall=3 timeout=1000 type=http;  # 異步健康檢查
    check_http_send "GET /health HTTP/1.1\r\nHost: backend\r\n\r\n";
    check_http_expect_alive http_2xx http_3xx;
}

http {
    keepalive_timeout 65;  # 長(zhǎng)連接超時(shí)時(shí)間
    keepalive_requests 100;  # 每個(gè)長(zhǎng)連接允許的最大請(qǐng)求數(shù)
    
    # 針對(duì)客戶端的長(zhǎng)連接
    keepalive_disable msie6;  # 禁用對(duì) IE6 的長(zhǎng)連接
    
    # 針對(duì)后端服務(wù)器的長(zhǎng)連接
    proxy_http_version 1.1;
    proxy_set_header Connection "";  # 移除 Connection 頭，啟用 HTTP/1.1 長(zhǎng)連接
}

location /async {
    proxy_pass http://backend;
    proxy_store on;  # 啟用響應(yīng)存儲(chǔ)（先寫(xiě)入磁盤再發(fā)送）
    proxy_store_access user:rw group:rw all:r;  # 存儲(chǔ)文件權(quán)限
}

location ~ \.php$ {
    fastcgi_pass 127.0.0.1:9000;
    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    
    # 異步 FastCGI 配置
    fastcgi_buffer_size 16k;
    fastcgi_buffers 4 32k;
    fastcgi_busy_buffers_size 64k;
    fastcgi_temp_file_write_size 64k;
    
    # 禁用緩沖可能導(dǎo)致阻塞，需謹(jǐn)慎
    # fastcgi_buffering off;
}

server {
    listen 443 ssl;
    server_name example.com;
    
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    
    # 異步 SSL 優(yōu)化
    ssl_session_cache shared:SSL:10m;  # 會(huì)話緩存
    ssl_session_timeout 10m;           # 會(huì)話超時(shí)時(shí)間
    ssl_prefer_server_ciphers on;      # 優(yōu)先使用服務(wù)器密碼套件
    
    # 啟用 OCSP 裝訂（異步驗(yàn)證證書(shū)）
    ssl_stapling on;
    ssl_stapling_verify on;
    resolver 8.8.8.8 8.8.4.4 valid=300s;
}

location /nginx_status {
    stub_status on;
    access_log off;
    allow 127.0.0.1;
    deny all;
}

log_format async '$remote_addr - $remote_user [$time_local] "$request" '
                 '$status $body_bytes_sent "$http_referer" '
                 '"$http_user_agent" pipe=$pipe time=$request_time';

access_log /var/log/nginx/access.log async;

# /etc/security/limits.conf
nginx   hard    nofile  65535
nginx   soft    nofile  65535