现象：

nginx restart 超时
nginx stop之后，80端口仍然被占用
在 kill调进程之后再启动
查看 systemctl status nginx

systemd[1]: Failed to read PID from file /run/nginx.pid: Invalid argument

百度结果：

Failed to read PID from file

因为 nginx 启动需要一点点时间，而 systemd 在 nginx 完成启动前就去读取 pid file
造成读取 pid 失败

解决方法很简单，让 systemd 在执行 ExecStart 的指令后等待一点点时间即可
如果你的 nginx 启动需要时间更长，可以把 sleep 时间改长一点

mkdir -p /etc/systemd/system/nginx.service.d
printf "[Service]\nExecStartPost=/bin/sleep 0.1\n" > /etc/systemd/system/nginx.service.d/override.conf

然后
systemctl daemon-reload
systemctl restart nginx.service

结果

[root@yumsources yum]# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; vendor preset: disabled)
  Drop-In: /etc/systemd/system/nginx.service.d
           └─override.conf
   Active: active (running) since Sat 2020-06-27 16:50:21 CST; 50s ago
  Process: 24397 ExecStartPost=/bin/sleep 0.1 (code=exited, status=0/SUCCESS)
  Process: 24393 ExecStart=/usr/sbin/nginx (code=exited, status=0/SUCCESS)
  Process: 24390 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCESS)
  Process: 24389 ExecStartPre=/usr/bin/rm -f /run/nginx.pid (code=exited, status=0/SUCCESS)
 Main PID: 24396 (nginx)
   CGroup: /system.slice/nginx.service
           ├─24396 nginx: master process /usr/sbin/nginx
           └─24398 nginx: worker process

Jun 27 16:50:21 yumsources systemd[1]: Starting The nginx HTTP and reverse proxy server...
Jun 27 16:50:21 yumsources nginx[24390]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
Jun 27 16:50:21 yumsources nginx[24390]: nginx: configuration file /etc/nginx/nginx.conf test is successful
Jun 27 16:50:21 yumsources systemd[1]: Started The nginx HTTP and reverse proxy server.