error: db5 error(11) from dbenv-＞open: Resource temporarily unavailable

CentOS7使用yum安装软件出现如下错误：

error: db5 error(11) from dbenv->open: Resource temporarily unavailable
error: cannot open Packages index using db5 - Resource temporarily unavailable (11)
error: cannot open Packages database in /var/lib/rpm
CRITICAL:yum.main:

Error: rpmdb open failed

#rpm --rebuilddb

# yum makecache

恢复正常。