Another app is currently holding the yum lock; waiting for it to exit... The other application is:

版权声明：@抛物线 https://blog.csdn.net/qq_28513801/article/details/89458253

使用yum命令时 或者清除缓存时 yum clean all 时 出现

Loaded plugins: fastestmirror
Existing lock /var/run/yum.pid: another copy is running as pid 12609.
Another app is currently holding the yum lock; waiting for it to exit…
The other application is: yum
Memory : 33 M RSS (425 MB VSZ)
Started: Mon Apr 22 06:34:09 2019 - 02:44 ago
State : Sleeping, pid: 12609
Another app is currently holding the yum lock; waiting for it to exit…
The other application is: yum
Memory : 33 M RSS (425 MB VSZ)
Started: Mon Apr 22 06:34:09 2019 - 02:46 ago
State : Sleeping, pid: 12609
…………………

 原因可能是：可能是系统自动升级正在运行，yum在锁定状态中。 
 已经有一个yum进程在运行了，使用kill干掉它：
 # kill -s 9 12609
 ps aux|grep yum
 root      6744  0.0  0.0 103260   900 pts/1    S+   14:59   0:00 grep yum
 root     12609 0.0  0.0      0     0 ?        Z    Sep19   0:01 [yumBackend.py] <defunct>

发现还是没有解决掉这个状态
那就
通过强制关掉yum进程：

 #rm -rf /var/run/yum.pid