Another app is currently holding the yum lock; waiting for it to exit…

yumでupdateを実行したら、

[root@localhost ~]# yum update
Loaded plugins: fastestmirror, priorities
Existing lock /var/run/yum.pid: another copy is running as pid 9334.
Another app is currently holding the yum lock; waiting for it to exit…
The other application is: system-install-
Memory : 56 M RSS (129 MB VSZ)
Started: Sat Oct 22 19:04:51 2011 – 1:20:17 ago
State : Sleeping, pid: 9334

と出てきた。

これは、pid 9334が使用しているとの警告。
よって、このプロセスの終了を待つか、強制的に「kill 9334」で終了させる必要あり！