Solution : Another app is currently holding the yum lock(fedora 15(64-bit))

There are two ways to solve the above problem:

1.You must be seeing some pid there , simply type the following command:

kill <pid>

2.If the above solution does not work then this will certainly work.

I.  ps aux | grep yum

II.  ps -e | grep yum kill -SIGKILL <pid>

Thank you.