yum 时候出现Another app is currently holding the yum lock解决方法

[root@localhost wangcheng]# yum install yumex Existing lock /var/run/yum.pid: another copy is running as pid 3807. Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... Another app is currently holding the yum lock; waiting for it to exit... 
这是什么原因？
 /var/run/yum.pid我打开看了，只是一个数，其他的 可能是系统自动升级正在运行，所以yum被锁定了。 
 可以通过执行
 rm -rf /var/run/yum.pid 
 来强行解除锁定，然后你的yum就可以运行了。