問題描述

服務(wù)器環(huán)境：

• php：8.4
• MySQL：8.0
• Nginx：1.26.2

在訪問站點時，一直報502，而兩天前還能正常訪問。

問題排查

導(dǎo)致502的問題很多，比如站點訪問量太大，站點受到了攻擊等，但是我看了后臺，重啟了Nginx，也沒解決?，F(xiàn)在遇到問題，首選就用AI來診斷。

我先復(fù)制了網(wǎng)站的錯誤日志：

2025/03/07 13:16:26 [crit] 795740#0: *2451 connect() to unix:/tmp/php-cgi-84.sock failed (2: No such file or directory) while connecting to upstream, client: 66.249.66.21, server: www.imqd.cn, request: ＂GET /robots.txt HTTP/1.1＂, upstream: ＂fastcgi://unix:/tmp/php-cgi-84.sock:＂, host: ＂www.imqd.cn＂
2025/03/07 13:16:26 [crit] 795740#0: *2450 connect() to unix:/tmp/php-cgi-84.sock failed (2: No such file or directory) while connecting to upstream, client: 66.249.66.1, server: www.imqd.cn, request: ＂GET /tag/es6 HTTP/1.1＂, upstream: ＂fastcgi://unix:/tmp/php-cgi-84.sock:＂, host: ＂www.imqd.cn＂

丟給ChatGPT，然后它回復(fù)的解決方案有點多，我用了下面這一條：

# 將該指令復(fù)制，并在站點目錄下執(zhí)行命令行
systemctl list-units --type=service | grep php

輸出：

php-fpm-74.service                       loaded active running LSB: starts php-fpm
● php-fpm-84.service                     loaded failed failed  LSB: starts php-fpm

錯誤如上：

表示我的環(huán)境中安裝了2個php版本，其中Nginx 試圖使用 PHP 8.4 (php-fpm-84)，但它 無法啟動，所以 502 Bad Gateway。

問題解決

這個我之前是用PHP8.4來運行WordPress站點的，現(xiàn)在它的服務(wù)遇到了問題，導(dǎo)致502問題。

所以很簡單的解決方式就是將WordPress的PHP版本切換為7.4即可。

但是為什么會導(dǎo)致8.4 用不了呢？wp運行在PHP8中更安全。

查看PHP的日志:

[14-Feb-2025 04:04:02] NOTICE: child 322153 stopped for tracing
[14-Feb-2025 04:04:02] NOTICE: about to trace 322153
[14-Feb-2025 04:04:02] NOTICE: finished trace of 322153
[15-Feb-2025 17:18:04] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 1 idle, and 22 total children
[15-Feb-2025 17:18:05] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 16 children, there are 3 idle, and 26 total children
[16-Feb-2025 17:52:51] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 2 idle, and 27 total children
[16-Feb-2025 17:52:52] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 16 children, there are 3 idle, and 30 total children
[16-Feb-2025 17:52:53] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 2 idle, and 32 total children
[17-Feb-2025 04:01:49] WARNING: [pool www] child 1221397, script '/www/wwwroot/www.cn/wp-admin/admin-ajax.php' (request: "GET /wp-admin/admin-ajax.php?action=wordfence_doScan&isFork=0&scanMode=standard&cronKey=c1d5082357026a61a2ce6e9feff7f549&signature=31aa3d000f5f2053ad504322212ad58a52a5a0e3032b25317bbdc7ef656b0606") executing too slow (34.708130 sec), logging
[17-Feb-2025 04:01:49] NOTICE: child 1221397 stopped for tracing
[17-Feb-2025 04:01:49] NOTICE: about to trace 1221397
[17-Feb-2025 04:01:49] NOTICE: finished trace of 1221397
[17-Feb-2025 10:57:21] NOTICE: Terminating ...
[17-Feb-2025 10:57:21] NOTICE: exiting, bye-bye!

發(fā)現(xiàn)了2個問題：

PHP-FPM 進程池（pool www）資源不足，服務(wù)器負載過高

• 日志多次提示 seems busy，說明 PHP 進程太少，導(dǎo)致請求等待時間變長。
• 你可能需要 增加 PHP-FPM 的進程數(shù)（pm.start_servers、pm.min/max_spare_servers）。

某些 PHP 腳本執(zhí)行太慢，導(dǎo)致超時

• 日志中顯示 admin-ajax.php 執(zhí)行時間過長（34.7 秒），可能是 WordPress 插件（如 Wordfence）在運行掃描任務(wù)，影響了服務(wù)器性能。

所以歸根結(jié)底還是服務(wù)器配置不夠，并且因為我開啟了Wordfence插件掃描導(dǎo)致的原因。

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