抱歉，这看起来有点杂乱。在过去的 20 个小时里，我一直在尝试排除故障/解决这个问题，同时每次服务器出现故障时都要照看服务器并重新启动 php5-fpm。
我猜想插件（高流量 WordPress 网站）或其他挂起该线程的东西存在潜在问题，可能导致依赖项锁定，从而占用其他线程。我最关心的是找到方法让 emergency_restart_threshold 在需要时自动重新启动 php5-fpm。然后我就可以睡觉了，并找到潜在的 PHP 问题。这个问题在过去 24 小时内发生了 21 次。有时相隔长达 3.5 小时，有时只有几分钟。
我尝试了各种计时值，但到目前为止似乎没有任何东西可以触发所需的 SIGSEGV 或 SIGBUS 信号。看起来一旦问题开始，所有 PHP 请求都会挂起，就像它们都在等待某事一样，并且 150 个最大子进程最终会被传入的请求填满，然后各种超时会将它们杀死。除了发生此问题时，通常只需要 2-5 个子进程即可满足当前流量。
服务器规格
服务器是运行 Ubuntu 14.04 的 Amazon EC2 c4.Xlarge（7.3 Gb RAM，4 vCPU）。
我还安装了 New Relic，资源似乎非常好。超过一半的内存可用，CPU 使用率通常远低于 50%，除非 PHP5-FPM 挂起。
我目前配置的各种配置文件
等/apache2/apache2.conf
Mutex file:${APACHE_LOCK_DIR} default
PidFile ${APACHE_PID_FILE}
Timeout 40
KeepAlive On
MaxKeepAliveRequests 250
KeepAliveTimeout 6
User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}
HostnameLookups Off
ErrorLog ${APACHE_LOG_DIR}/error.log
LogLevel error
IncludeOptional mods-enabled/*.load
IncludeOptional mods-enabled/*.conf
Include ports.conf
<Directory />
Options +FollowSymLinks -SymLinksIfOwnerMatch
AllowOverride None
Require all denied
</Directory>
<Directory /usr/share>
AllowOverride None
Require all granted
</Directory>
<Directory /var/www/>
Options +FollowSymLinks -SymLinksIfOwnerMatch
AllowOverride All
Require all granted
</Directory>
AccessFileName .htaccess
<FilesMatch "^\.ht">
Require all denied
</FilesMatch>
LogFormat "%{User-agent}i" agent
IncludeOptional conf-enabled/*.conf
IncludeOptional sites-enabled/*.conf
SSLProtocol ALL -SSLv2
SSLCipherSuite ECDHE-RSA-AES256-SHA384:AES256-SHA256:AES256-SHA256:RC4:HIGH:MEDIUM:+TLSv1:+TLSv1.1:+TLSv1.2:!MD5:!ADH:!aNULL:!eNULL:!NULL:!DH:!ADH:!EDH:!AESGCM
<IfModule fastcgi_module>
Action fastcgi-php5-fpm /fastcgi.php5-fpm virtual
Alias /fastcgi.php5-fpm /var/www/cgi-bin/fastcgi.php5-fpm -socket /var/run/fastcgi/USERNAME.socket -appConnTimeout 10 -idle-timeout 250 -pass-header Authorization
FastCgiExternalServer /var/www/cgi-bin/fastcgi.php5-fpm -socket /var/run/php5-fpm.sock -idle-timeout 15 -appConnTimeout 0 -pass-header Authorization -pass-header Range
AddHandler fastcgi-php5-fpm php phar
<Directory /var/www/cgi-bin>
AllowOverride none
Options FollowSymLinks
<IfModule authz_core_module>
Require env REDIRECT_STATUS
Options +ExecCGI
</IfModule>
</Directory>
</IfModule>
<IfModule mpm_event_module>
Timeout 300
StartServers 3
ThreadLimit 50
ThreadsPerChild 50
MaxConnectionsPerChild 10000
MinSpareThreads 50
MaxSpareThreads 250
ServerLimit 600
MaxRequestWorkers 600
KeepAlive on
MaxKeepAliveRequests 100
KeepAliveTimeout 5
</IfModule>
等/php5/fpm/php-fpm.conf
[global]
pid = /var/run/php5-fpm.pid
error_log = log/php5-fpm.log
syslog.facility = daemon
syslog.ident = php-fpm
log_level = debug
;log_level = notice
; If this number of child processes exit with SIGSEGV or SIGBUS within the time
; interval set by emergency_restart_interval then FPM will restart. A value
; of '0' means 'Off'.
; Default Value: 0
emergency_restart_threshold = 3
; Interval of time used by emergency_restart_interval to determine when
; a graceful restart will be initiated. This can be useful to work around
; accidental corruptions in an accelerator's shared memory.
; Available Units: s(econds), m(inutes), h(ours), or d(ays)
; Default Unit: seconds
; Default Value: 0
emergency_restart_interval = 2m
; Time limit for child processes to wait for a reaction on signals from master.
; Available units: s(econds), m(inutes), h(ours), or d(ays)
; Default Unit: seconds
; Default Value: 0
process_control_timeout = 5s
include=/etc/php5/fpm/pool.d/*.conf
etc/php5/fpm/pool.d/www.conf
[www]
user = www-data
group = www-data
listen = /var/run/php5-fpm.sock
; Set listen(2) backlog.
; Default Value: 65535 (-1 on FreeBSD and OpenBSD)
;listen.backlog = 65535
; Set permissions for unix socket, if one is used. In Linux, read/write
; permissions must be set in order to allow connections from a web server. Many
; BSD-derived systems allow connections regardless of permissions.
; Default Values: user and group are set as the running user
; mode is set to 0660
listen.owner = www-data
listen.group = www-data
;listen.mode = 0660
pm = dynamic
pm.max_children = 150
pm.start_servers = 10
pm.min_spare_servers = 10
pm.max_spare_servers = 30
pm.process_idle_timeout = 10s
pm.max_requests = 40
pm.status_path = /public_html/bvt-fpmstatus.php
access.log = /var/log/$pool.access.log
access.format = %T %R \"%m %r%Q%q\" - %s %u %f %{mili}d %{kilo}M %C%% %t"
; The log file for slow requests
; Default Value: not set
; Note: slowlog is mandatory if request_slowlog_timeout is set
;slowlog = /var/log/$pool.log.slow
;request_slowlog_timeout = 25s
; The timeout for serving a single request after which the worker process will
; be killed. This option should be used when the 'max_execution_time' ini option
; does not stop script execution for some reason. A value of '0' means 'off'.
; Available units: s(econds)(default), m(inutes), h(ours), or d(ays)
; Default Value: 0
request_terminate_timeout = 31s
; Chroot to this directory at the start. This value must be defined as an
; absolute path. When this value is not set, chroot is not used.
; Note: you can prefix with '$prefix' to chroot to the pool prefix or one
; of its subdirectories. If the pool prefix is not set, the global prefix
; will be used instead.
; Note: chrooting is a great security feature and should be used whenever
; possible. However, all PHP paths will be relative to the chroot
; (error_log, sessions.save_path, ...).
; Default Value: not set
;chroot =
; Chdir to this directory at the start.
; Note: relative path can be used.
; Default Value: current directory or / when chroot
chdir = /
; Redirect worker stdout and stderr into main error log. If not set, stdout and
; stderr will be redirected to /dev/null according to FastCGI specs.
; Note: on highloaded environement, this can cause some delay in the page
; process time (several ms).
; Default Value: no
php_admin_value[display_errors] = stderr
catch_workers_output = yes ; Add to Apache log.
; Limits the extensions of the main script FPM will allow to parse. This can
; prevent configuration mistakes on the web server side. You should only limit
; FPM to .php extensions to prevent malicious users to use other extensions to
; exectute php code.
; Note: set an empty value to allow all extensions.
; Default Value: .php
security.limit_extensions = .php .php3 .php4 .php5 .phar
; Pass environment variables like LD_LIBRARY_PATH. All $VARIABLEs are taken from
; the current environment.
; Default Value: clean env
;env[HOSTNAME] = $HOSTNAME
;env[PATH] = /usr/local/bin:/usr/bin:/bin
;env[TMP] = /tmp
;env[TMPDIR] = /tmp
;env[TEMP] = /tmp
php_admin_flag[log_errors] = on
;php_admin_flag[display_errors] = stderr ; Send displayed errors to error stream instead of screen
;php_admin_value[error_reporting] = 2147483647 ; Log all (WARNING: very verbose)
;php_admin_value[memory_limit] = 32M
php_admin_value[upload_max_filesize] = 32M
php_admin_value[post_max_size] = 32M
php_admin_value[max_execution_time] = 30
日志摘录
/var/log/upstart/php5-fpm.log
PHP_FPM重启后@09:54正常运行：
[11-Mar-2015 09:54:03] NOTICE: fpm is running, pid 17478
[11-Mar-2015 09:54:03] NOTICE: ready to handle connections
[11-Mar-2015 09:54:03] NOTICE: systemd monitor interval set to 10000ms
[11-Mar-2015 09:59:51] NOTICE: [pool www] child 17481 exited with code 0 after 348.302350 seconds from start
[11-Mar-2015 09:59:51] NOTICE: [pool www] child 17978 started
[11-Mar-2015 09:59:54] NOTICE: [pool www] child 17488 exited with code 0 after 350.794698 seconds from start
[11-Mar-2015 09:59:54] NOTICE: [pool www] child 17982 started
[11-Mar-2015 09:59:54] NOTICE: [pool www] child 17485 exited with code 0 after 351.236038 seconds from start
[11-Mar-2015 09:59:54] NOTICE: [pool www] child 17985 started
[11-Mar-2015 10:00:01] NOTICE: [pool www] child 17486 exited with code 0 after 357.770981 seconds from start
[11-Mar-2015 10:00:01] NOTICE: [pool www] child 17995 started
[11-Mar-2015 10:00:01] NOTICE: [pool www] child 17484 exited with code 0 after 358.020653 seconds from start
[11-Mar-2015 10:00:01] NOTICE: [pool www] child 17996 started
[11-Mar-2015 10:00:02] NOTICE: [pool www] child 17483 exited with code 0 after 358.627602 seconds from start
[11-Mar-2015 10:00:02] NOTICE: [pool www] child 18048 started
[11-Mar-2015 10:00:02] NOTICE: [pool www] child 17487 exited with code 0 after 358.753904 seconds from start
[11-Mar-2015 10:00:02] NOTICE: [pool www] child 18049 started
[11-Mar-2015 10:00:03] NOTICE: [pool www] child 17489 exited with code 0 after 360.321755 seconds from start
[11-Mar-2015 10:00:03] NOTICE: [pool www] child 18053 started
[11-Mar-2015 10:00:05] NOTICE: [pool www] child 17490 exited with code 0 after 361.648421 seconds from start
[11-Mar-2015 10:00:05] NOTICE: [pool www] child 18061 started
[11-Mar-2015 10:00:05] NOTICE: [pool www] child 17494 exited with code 0 after 359.677309 seconds from start
[11-Mar-2015 10:00:05] NOTICE: [pool www] child 18062 started
[11-Mar-2015 10:00:11] NOTICE: [pool www] child 17482 exited with code 0 after 368.373606 seconds from start
[11-Mar-2015 10:00:11] NOTICE: [pool www] child 18070 started
然后我们开始看到麻烦的第一个迹象（此时服务器 CPU 和内存仍然状况良好）：
[11-Mar-2015 10:13:02] NOTICE: [pool www] child 19380 started
[11-Mar-2015 10:13:04] NOTICE: [pool www] child 18791 exited with code 0 after 380.518655 seconds from start
[11-Mar-2015 10:13:04] NOTICE: [pool www] child 19381 started
[11-Mar-2015 10:13:04] NOTICE: [pool www] child 18787 exited with code 0 after 382.270838 seconds from start
[11-Mar-2015 10:13:04] NOTICE: [pool www] child 19382 started
[11-Mar-2015 10:13:05] NOTICE: [pool www] child 18794 exited with code 0 after 378.655639 seconds from start
[11-Mar-2015 10:13:05] NOTICE: [pool www] child 19384 started
[11-Mar-2015 10:15:28] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 7 idle, and 20 total children
[11-Mar-2015 10:15:41] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 8 idle, and 32 total children
[11-Mar-2015 10:15:46] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 8 children, there are 8 idle, and 38 total children
[11-Mar-2015 10:15:47] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 16 children, there are 9 idle, and 40 total children
[11-Mar-2015 10:15:48] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 8 idle, and 41 total children
[11-Mar-2015 10:15:49] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 9 idle, and 43 total children
[11-Mar-2015 10:15:50] WARNING: [pool www] seems busy (you may need to increase pm.start_servers, or pm.min/max_spare_servers), spawning 32 children, there are 9 idle, and 44 total children
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19384, script '/var/www/html/index.php' (request: "GET /index.php") execution timed out (31.932041 sec), terminating
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19382, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (32.027672 sec), terminating
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19366, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (31.208359 sec), terminating
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19363, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (32.113767 sec), terminating
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19355, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (31.057660 sec), terminating
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19351, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (32.977536 sec), terminating
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19384 exited on signal 15 (SIGTERM) after 170.885585 seconds from start
[11-Mar-2015 10:15:55] NOTICE: [pool www] child 19760 started
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19366 exited on signal 15 (SIGTERM) after 184.386893 seconds from start
[11-Mar-2015 10:15:55] NOTICE: [pool www] child 19761 started
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19382 exited on signal 15 (SIGTERM) after 171.442721 seconds from start
[11-Mar-2015 10:15:55] NOTICE: [pool www] child 19762 started
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19355 exited on signal 15 (SIGTERM) after 193.595364 seconds from start
[11-Mar-2015 10:15:55] NOTICE: [pool www] child 19764 started
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19351 exited on signal 15 (SIGTERM) after 195.910381 seconds from start
[11-Mar-2015 10:15:55] NOTICE: [pool www] child 19765 started
[11-Mar-2015 10:15:55] WARNING: [pool www] child 19363 exited on signal 15 (SIGTERM) after 187.115830 seconds from start
[11-Mar-2015 10:15:55] NOTICE: [pool www] child 19766 started
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19657, script '/var/www/html/public_html/wp-admin/admin-ajax.php' (request: "POST /public_html/wp-admin/admin-ajax.php") execution timed out (31.374989 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19656, script '/var/www/html/public_html/wp-admin/admin-ajax.php' (request: "POST /public_html/wp-admin/admin-ajax.php") execution timed out (33.896470 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19652, script '/var/www/html/public_html/wp-admin/admin-ajax.php' (request: "POST /public_html/wp-admin/admin-ajax.php") execution timed out (35.011947 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19651, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (35.830626 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19381, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (38.100342 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19371, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (39.258347 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19365, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (39.064079 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19360, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (37.983709 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19356, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (40.136172 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19272, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (38.265691 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19229, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (34.137729 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19091, script '/var/www/html/public_html/wp-admin/admin-ajax.php' (request: "POST /public_html/wp-admin/admin-ajax.php") execution timed out (38.957131 sec), terminating
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19651 exited on signal 15 (SIGTERM) after 40.426680 seconds from start
[11-Mar-2015 10:16:06] NOTICE: [pool www] child 19840 started
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19091 exited on signal 15 (SIGTERM) after 384.915614 seconds from start
[11-Mar-2015 10:16:06] NOTICE: [pool www] child 19841 started
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19381 exited on signal 15 (SIGTERM) after 182.183820 seconds from start
[11-Mar-2015 10:16:06] NOTICE: [pool www] child 19842 started
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19652 exited on signal 15 (SIGTERM) after 39.431626 seconds from start
[11-Mar-2015 10:16:06] NOTICE: [pool www] child 19843 started
[11-Mar-2015 10:16:06] WARNING: [pool www] child 19656 exited on signal 15 (SIGTERM) after 38.430261 seconds from start
[11-Mar-2015 10:16:06] NOTICE: [pool www] child 19844 started
这种情况一直持续到我注意到子进程快速升级（并打开 MySQL 连接）。此时我将重新启动 PHP_FPM 服务（@ 10:18:54）。这次我在它用完 150 个最大子进程之前就抓住了它，但是所有 PHP 脚本都不再收到 200 个回复。崩溃是不可避免的。
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20080, script '/var/www/html/index.php' (request: "GET /index.php") execution timed out (39.148257 sec), terminating
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20079, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (40.497106 sec), terminating
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20078, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (40.785344 sec), terminating
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20077, script '/var/www/html/public_html/index.php' (request: "GET /public_html/index.php") execution timed out (41.271773 sec), terminating
[11-Mar-2015 10:18:51] WARNING: [pool www] child 19969, script '/var/www/html/public_html/wp-content/plugins/w3-total-cache/pub/minify.php' (request: "GET /public_html/wp-content/plugins/w3-total-cache/pub/minify.php") execution timed out (33.608193 sec), terminating
[11-Mar-2015 10:18:51] WARNING: [pool www] child 19969 exited on signal 15 (SIGTERM) after 113.661735 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20279 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20081 exited on signal 15 (SIGTERM) after 62.003482 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20280 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20084 exited on signal 15 (SIGTERM) after 62.001519 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20283 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20077 exited on signal 15 (SIGTERM) after 62.009634 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20284 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20078 exited on signal 15 (SIGTERM) after 62.009429 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20285 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20079 exited on signal 15 (SIGTERM) after 62.009275 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20286 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20080 exited on signal 15 (SIGTERM) after 62.007759 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20287 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20097 exited on signal 15 (SIGTERM) after 51.677646 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20288 started
[11-Mar-2015 10:18:51] WARNING: [pool www] child 20100 exited on signal 15 (SIGTERM) after 51.675055 seconds from start
[11-Mar-2015 10:18:51] NOTICE: [pool www] child 20289 started
[11-Mar-2015 10:18:54] NOTICE: Terminating ...
[11-Mar-2015 10:18:54] NOTICE: exiting, bye-bye!
[2015 年 3 月 11 日星期三 09：54：03.411897] [fastcgi：error] [pid 13072：tid 140351645890304] [客户端 222.153.85.53:55464] FastCGI：从服务器“/var/www/cgi-bin/fastcgi.php5-fpm”接收到不完整的标头（0 字节），引用者：https://www.thewebsitedomain.com/public_html/some-post/ [2015 年 3 月 11 日星期三 09：54：03.418052] [fastcgi：error] [pid 13072：tid 140351486428928]（104）对等方重置连接：[客户端 84.202.21.98:52139] FastCGI：与服务器“/var/www/cgi-bin/fastcgi.php5-fpm”通信已中止：读取失败 [2015 年 3 月 11 日星期三 09：54：03.418078] [fastcgi：error] [pid 13072：tid 140351486428928] [客户端 84.202.21.98:52139] FastCGI：从服务器接收到不完整的标头（0 字节） “/var/www/cgi-bin/fastcgi.php5-fpm” [2015 年 3 月 11 日星期三 10：15：19.031557] [：error] [pid 18669：tid 140351536785152] [客户端 62.108.27.152:56596] FastCGI：服务器“/var/www/cgi-bin/fastcgi.php5-fpm”stderr：主脚本未知 [2015 年 3 月 11 日星期三 10：15：55.905638] [fastcgi：error] [pid 18728：tid 140351394109184]（104）对等方重置连接：[客户端 211.28.60.59:53044] FastCGI：与服务器通信“/var/www/cgi-bin/fastcgi.php5-fpm” 中止：读取失败 [2015 年 3 月 11 日星期三 10：15：55.905681] [fastcgi：error] [pid 18728：tid 140351394109184] [客户端 211.28.60.59:53044] FastCGI：从服务器“/var/www/cgi-bin/fastcgi.php5-fpm”接收到不完整的标头（0 字节） [2015 年 3 月 11 日星期三 10：15：55.906363] [fastcgi：error] [pid 18669：tid 140351494821632]（104）对等方重置连接：[客户端 58.174.227.102:61362] FastCGI：与服务器“/var/www/cgi-bin/fastcgi.php5-fpm”的通信中止：读取失败，引用：https://www.thewebsitedomain.com/public_html/some-post/page/3/
/var/log/apache2/error.log（域名和 URL 已更改）
其中有很多条目，但它们都属于下面看到的两类。
FastCGI: comm with server "/var/www/cgi-bin/fastcgi.php5-fpm" aborted: read failed当我手动重新启动 php-fpm 时，它会强制关闭所有仍然打开的连接，从而生成这些错误。
这些stderr: Primary script unknown问题是由于机器人尝试随机 URL 并导致 404 错误而引起的。
[Wed Mar 11 12:28:53.135352 2015] [:error] [pid 31126:tid 139952113252096] [client 188.40.153.39:46874] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown
[Wed Mar 11 12:28:54.344039 2015] [:error] [pid 437:tid 139952197179136] [client 188.40.153.39:46875] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown
[Wed Mar 11 12:40:25.086767 2015] [:error] [pid 437:tid 139952338970368] [client 49.4.164.66:55601] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown
[Wed Mar 11 12:40:27.536523 2015] [:error] [pid 437:tid 139952079681280] [client 49.4.164.66:55847] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown
[Wed Mar 11 12:45:08.438864 2015] [:error] [pid 437:tid 139952347363072] [client 5.39.218.220:35839] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown
[Wed Mar 11 12:56:02.328823 2015] [core:error] [pid 437:tid 139952330577664] [client 41.13.228.41:26895] AH00126: Invalid URI in request POST ww.thewebsitedomain.com/public_html/wp-admin/admin-ajax.php HTTP/1.1
[Wed Mar 11 13:01:01.058193 2015] [:error] [pid 31126:tid 139952146822912] [client 69.12.90.191:58259] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown, referer: https://www.thewebsitedomain.com/
[Wed Mar 11 13:01:02.346250 2015] [:error] [pid 31126:tid 139952355755776] [client 69.12.90.191:58259] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown, referer: https://www.thewebsitedomain.com/wp-login.php?action=register
[Wed Mar 11 13:10:11.007667 2015] [:error] [pid 4074:tid 139952062895872] [client 23.94.222.15:53539] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown, referer: https://www.thewebsitedomain.com/
[Wed Mar 11 13:10:11.671945 2015] [:error] [pid 4074:tid 139952330577664] [client 23.94.222.15:53539] FastCGI: server "/var/www/cgi-bin/fastcgi.php5-fpm" stderr: Primary script unknown, referer: https://www.thewebsitedomain.com/wp-login.php?action=register
我保存了许多其他日志，以及我尝试进行的各种配置更改的详细说明。不确定还有什么可能相关。很高兴发布任何其他有用的信息。
感谢大家提出的所有建议，希望能够找到解决方案。即使这只是一个临时解决办法，我也可以让服务器在足够长的时间内无人值守，以便休眠和充电。