现在我们在配备4核SAS 15k驱动器(raid10)的机器上运行Nginx(1.0.10)和PHP-FPM,配备16核cpu和24GB DDR3内存.我们还使用了最新的Xcache版本. DB位于另一台机器上,但该机器的负载非常低,并且没有问题.

在正常负载下,一切运行完美,系统负载低于1,并且PHP-FPM状态报告从未真正一次显示超过10个活动进程.总有大约10GB的ram可用.在正常负载下,机器每秒处理大约100次综合浏览量.

当流量大幅上升到达时,问题就出现了,并且机器要求每秒数百次页面浏览量.我注意到FPM的状态报告随后显示多达50个活动进程,但这仍然低于我们配置的300个最大连接数.在这些峰值期间,Nginx状态报告最多5000个活动连接,而不是正常平均值1000.

操作系统信息：CentOS 5.7版(最终版)

cpu：Intel(R)Xeon(R)cpu E5620 @ 2.40GH(16核)

PHP-fpm.conf

daemonize = yes
listen = /tmp/fpm.sock
pm = static
pm.max_children = 300
pm.max_requests = 1000

我没有设置rlimit_files,因为据我所知它应该使用系统默认值,如果你不这样做.

fastcgi_params(仅向标准文件添加值)

fastcgi_connect_timeout 60;
fastcgi_send_timeout 180;
fastcgi_read_timeout 180;
fastcgi_buffer_size 128k;
fastcgi_buffers 4 256k;
fastcgi_busy_buffers_size 256k;
fastcgi_temp_file_write_size 256k;
fastcgi_intercept_errors on;

fastcgi_pass            unix:/tmp/fpm.sock;

Nginx.conf

worker_processes        8;
worker_connections      16384;
sendfile                on;
tcp_nopush              on;
keepalive_timeout       4;

Nginx通过Unix Socket连接到FPM.

sysctl.conf的

net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 1
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.tcp_max_syn_backlog = 2048
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.default.secure_redirects = 0
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.tcp_timestamps = 0
net.ipv4.conf.all.rp_filter=1
net.ipv4.conf.default.rp_filter=1
net.ipv4.conf.eth0.rp_filter=1
net.ipv4.conf.lo.rp_filter=1
net.ipv4.ip_conntrack_max = 100000

limits.conf中

* soft nofile 65536
* hard nofile 65536

这些是以下命令的结果：

ulimit -n
65536

ulimit -Sn
65536

ulimit -Hn
65536

cat /proc/sys/fs/file-max
2390143

问：如果PHP-FPM没有用完连接,那么负载仍然很低,并且有足够的RAM可用,在高流量期间可能导致这些随机502网关错误的瓶颈是什么？

注意：默认情况下,这台机器的ulimit是1024,因为我把它改为65536我没有完全重启机器,因为它是一台生产机器,这意味着停机时间过长.