由于 PHP-FPM 监听队列，网站无法访问，CPU 达到 100%

Question

我一直在绞尽脑汁试图解决这个问题，该问题每隔几个小时就会在托管单个 Wordpress 博客的生产服务器上随机出现一次（流量不错：平均每天实时有 2000 名用户，好的时候有 5000 多名用户，每分钟的页面浏览量从 300 到 700+ 不等）。

我使用 Newrelic 来监控性能并注意到一件奇怪的事情：

每隔几个小时（随机），PHP-FPM 池状态如下所示（昨天获取的实际状态）

pool:                 www
process manager:      static
start time:           02/Jan/2017:05:03:16 -0500
start since:          27290
accepted conn:        1107594
listen queue:         777
max listen queue:     794
listen queue len:     40000
idle processes:       0
active processes:     100
total processes:      100
max active processes: 101
max children reached: 0
slow requests:        0

重新启动PHP-FPM并nginx解决问题，但几个小时后又再次发生。任何帮助都非常感谢。请指导我。

---

服务器设置：

DigitalOcean 48GB Memory
16 Core Processor
480GB SSD Disk

PHP-FPM 池设置：

pm = static
pm.max_children = 100
pm.max_requests = 5000

nginx配置：

worker_processes  32;
worker_rlimit_nofile 100000;
events {
    worker_connections  40000;
    use epoll;
    multi_accept on;
}

xcache我也在Wordpressvarnish上使用W3TC。（也有 Cloudflare）

系统配置信息：

# Increase size of file handles and inode cache
fs.file-max = 2097152

# Do less swapping
vm.swappiness = 10
vm.dirty_ratio = 60
vm.dirty_background_ratio = 2

### GENERAL NETWORK SECURITY OPTIONS ###

# Number of times SYNACKs for passive TCP connection.
net.ipv4.tcp_synack_retries = 2

# Allowed local port range
net.ipv4.ip_local_port_range = 2000 65535

# Protect Against TCP Time-Wait
net.ipv4.tcp_rfc1337 = 1

# Decrease the time default value for tcp_fin_timeout connection
net.ipv4.tcp_fin_timeout = 15

# Decrease the time default value for connections to keep alive
net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_keepalive_probes = 5
net.ipv4.tcp_keepalive_intvl = 15

### TUNING NETWORK PERFORMANCE ###

# Default Socket Receive Buffer
net.core.rmem_default = 31457280

# Maximum Socket Receive Buffer
net.core.rmem_max = 12582912

# Default Socket Send Buffer
net.core.wmem_default = 31457280

# Maximum Socket Send Buffer
net.core.wmem_max = 12582912

# Increase number of incoming connections
net.core.somaxconn = 40000

# Increase number of incoming connections backlog
net.core.netdev_max_backlog = 65536

# Increase the maximum amount of option memory buffers
net.core.optmem_max = 25165824

# Increase the maximum total buffer-space allocatable
# This is measured in units of pages (4096 bytes)
net.ipv4.tcp_mem = 65536 131072 262144
net.ipv4.udp_mem = 65536 131072 262144

# Increase the read-buffer space allocatable
net.ipv4.tcp_rmem= 10240 87380 12582912
net.ipv4.udp_rmem_min = 16384

# Increase the write-buffer-space allocatable
net.ipv4.tcp_wmem= 10240 87380 12582912
net.ipv4.udp_wmem_min = 16384

# Increase the tcp-time-wait buckets pool size to prevent simple DOS attacks
net.ipv4.tcp_max_tw_buckets = 1440000
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1