Another app is currently holding the yum lock; waiting for it to exit...另一个应用程序在占用yum lock，等待其退出。

这种情况下通常是由于yum的时候意外退出造成的，虽然也给出提示当前占用进行的id，但是执行kill -9 3599 强制杀死进程后，情况依然没能改变。

备注：（-9是强制杀死）

主要原因是因为，yum lock被占用，无法被其他yum操作获得，这里只需要删除/var/run/yum.pid即可：

[root@lemon run]# ls
abrt                     console      gdm                    hive            plymouth        syslogd.pid             wpa_supplicant
abrtd.pid                ConsoleKit   hadoop-0.20-mapreduce  httpd           pm-utils        tpvmlpd.pid             wpa_supplicant.pid
acpid.pid                crond.pid    hadoop-hdfs            lvm             portreserve     tpvmlpd.stat            yum.pid
acpid.socket             cron.reboot  hadoop-httpfs          mdadm           ppp             udev-configure-printer  zookeeper
atd.pid                  cups         hadoop-mapreduce       messagebus.pid  saslauthd       udisks
auditd.pid               cupsd.pid    hadoop-yarn            netreport       sepermit        utmp
cloudera-scm-agent       dbus         hald                   net-snmp        setrans         vmblock-fuse
cloudera-scm-server      faillock     haldaemon.pid          NetworkManager  spice-vdagentd  vmtoolsd.pid
cloudera-scm-server.pid  flume-ng     hbase                  oozie           sshd.pid        winbindd
[root@lemon run]# rm -rf yum.pid 
[root@lemon run]# pwd