修改文件描述符

配置ulimit -a
注：nofile最大值1048576，且不能设置为unlimited，否则无法ssh登陆，noproc可以

vim /etc/security/limits.conf  
* soft nofile 655360
* hard nofile 655360
* soft nproc  655360
* hard nproc  655360
vim /etc/security/limits.d/20-nproc.conf
* soft nofile 655360
* hard nofile 655360
* soft nproc 655360
* hard nproc 655360
echo "vm.max_map_count=655360" >> /etc/sysctl.conf && sysctl -p

针对centos7系统

/etc/security/limits.conf 文件的配置作用域缩小了一些。limits.conf这里的配置，只适用于通过PAM认证登录用户的资源限制，它对systemd的service的资源限制不生效。

systemctl启动的进程资源限制，可以通过修改 /etc/systemd/system.conf 后重启系统设置非用户的进程资源限制。

system.conf和user.conf添加

vi /etc/systemd/system.conf
DefaultLimitCORE=infinity
DefaultLimitNOFILE=655360
DefaultLimitNPROC=655360
vi /etc/systemd/user.conf
DefaultLimitCORE=infinity
DefaultLimitNOFILE=655360
DefaultLimitNPROC=655360

systemctl daemon-reload
systemctl daemon-reexec

查看某个进程的文件描述符配置

cat /proc/117424/limits
Limit                     Soft Limit           Hard Limit           Units     
Max cpu time              unlimited            unlimited            seconds   
Max file size             unlimited            unlimited            bytes     
Max data size             unlimited            unlimited            bytes     
Max stack size            8388608              unlimited            bytes     
Max core file size        0                    unlimited            bytes     
Max resident set          unlimited            unlimited            bytes     
Max processes             655360               655360               processes 
Max open files            655360               655360               files     
Max locked memory         65536                65536                bytes     
Max address space         unlimited            unlimited            bytes     
Max file locks            unlimited            unlimited            locks     
Max pending signals       1028649              1028649              signals   
Max msgqueue size         819200               819200               bytes     
Max nice priority         0                    0                    
Max realtime priority     0                    0                    
Max realtime timeout      unlimited            unlimited            us