Nginx
Nginx+PHP-FPM+APC+Varnish+Memcached：Mem/Swap消耗高？
我在 Linode 上執行了一個具有 1024 MB RAM、Ubuntu 11.04 和 Nginx+PHP-FPM+APC Varnish+Memcached 的 VPS。我用 WordPress 3.2.1 設置了幾個測試部落格，一切正常，性能測試看起來很有希望：
# ab -n 1000 -c 100 http://mydomain.com/ This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking mydomain.com (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Completed 600 requests Completed 700 requests Completed 800 requests Completed 900 requests Completed 1000 requests Finished 1000 requests Server Software: nginx Server Hostname: mydomain.com Server Port: 80 Document Path: / Document Length: 5677 bytes Concurrency Level: 100 Time taken for tests: 0.186 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 5989000 bytes HTML transferred: 5677000 bytes Requests per second: 5376.14 [#/sec] (mean) Time per request: 18.601 [ms] (mean) Time per request: 0.186 [ms] (mean, across all concurrent requests) Transfer rate: 31443.08 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 6 9 0.9 8 13 Processing: 4 9 1.3 9 14 Waiting: 1 5 2.5 5 13 Total: 12 18 1.6 18 22 WARNING: The median and mean for the initial connection time are not within a normal deviation These results are probably not that reliable. Percentage of the requests served within a certain time (ms) 50% 18 66% 19 75% 19 80% 19 90% 20 95% 21 98% 22 99% 22 100% 22 (longest request)安裝 Memcached 和 php5-memcache 包並啟用 WP Memcache 外掛後，我可以看到 memcache 伺服器已啟動並執行，命中率約為 50%。memcache 服務使用 64 MB 記憶體：
# ps xa |grep memcached 12259 ? Sl 0:01 /usr/bin/memcached -m 64 -p 11211 -u memcache -l 127.0.0.1不過，我可以看到的是主記憶體和交換的高消耗，我想知道這是否正常。伺服器大部分時間都是空閒的（測試部落格正在執行，但現在沒有人關心它們，所以我是唯一的訪問者），所以我不明白為什麼記憶體和交換這麼高。
#free -m total used free shared buffers cached Mem: 927 906 21 0 6 58 -/+ buffers/cache: 840 87 Swap: 255 255 0有任何想法嗎？
更新：似乎 Memcached 不是原因。我已經停止了伺服器，該站點當然正在執行，但記憶體/交換消耗仍然幾乎 100%。所以應該有問題，可能是PHP-FPM或Varnish？
更新 2：似乎 PHP-FPM 是問題，看看這個（感謝命令，Tomtezky）
# ps aux --sort=-rss | head -15 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND www-data 12414 0.0 9.6 247840 91772 ? S 01:25 0:06 php-fpm: pool www www-data 12405 0.0 9.5 244012 91212 ? S 01:25 0:06 php-fpm: pool www www-data 12418 0.0 9.0 241820 86132 ? S 01:25 0:05 php-fpm: pool www www-data 12417 0.0 8.5 236724 81500 ? S 01:25 0:07 php-fpm: pool www www-data 12409 0.0 8.2 241980 78784 ? S 01:25 0:05 php-fpm: pool www www-data 12407 0.0 8.1 236968 77880 ? S 01:25 0:05 php-fpm: pool www www-data 12400 0.0 8.1 234344 77860 ? S 01:25 0:06 php-fpm: pool www www-data 12408 0.0 8.1 237120 77700 ? S 01:25 0:06 php-fpm: pool www www-data 12410 0.0 8.0 232248 76224 ? S 01:25 0:06 php-fpm: pool www www-data 12413 0.0 7.6 242092 72452 ? S 01:25 0:07 php-fpm: pool www www-data 12416 0.0 7.1 241812 68148 ? S 01:25 0:05 php-fpm: pool www www-data 12412 0.0 7.0 220684 66644 ? S 01:25 0:04 php-fpm: pool www www-data 12402 0.0 6.9 241556 66156 ? S 01:25 0:05 php-fpm: pool www www-data 12419 0.0 6.2 238016 59304 ? S 01:25 0:04 php-fpm: pool www看到了……如何減少 PHP-FPM 的記憶體使用？
它不是 PHP-FPM，它是 PHP-FPM 中載入的 Wordpress 實例。限制 php-fpm worker 的數量，或者減少你的 wordpress 安裝的記憶體佔用。