nginx报错:socket() failed (24: Too many open files) while connecting to upstream

nginx反代新项目，在线人数过多时就会报错，查看日志，报错如下：

socket() failed (24: Too many open files) while connecting to upstream

解决办法

1.修改linux打开文件句柄数，编辑/etc/security/limits.conf，添加

*             soft   nofile          204800
*             hard   nofile          204800

2.修改nginx打开文件数, 编辑nginx.conf，添加worker_rlimit_nofile值

worker_processes  1;
 worker_rlimit_nofile 20480;

3.重启nginx后解决

./nginx -s stop 
./nginx