运行yum update的时候如果用Ctrl + C强制退出，再次运行yum的时候有如下错误：

Existing lock /var/run/yum.pid: another copy is running as pid 3053.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: PackageKit
Memory : 37 M RSS ( 82 MB VSZ)
Started: Sun Jan 24 16:11:53 2010 - 14:44 ago
State : Sleeping, pid: 3053

我试着用kill 3053强制结束进程，但是再运行yum还是不行，每次都重启解决的。