another app is currently holding the yum lock;waiting for it to exit...

有时用yum升级一些文件时，会出现以下情况：
another app is currently holding the yum lock;waiting for it to exit...
可以通过强制关掉yum进程：

解决方法： rm -rf /var/run/yum.pid 来强行解除锁定，然后你的yum就可以运行了