Ubuntu Package Installation Error lock the administration directory (/var/lib/dpkg/

while I install the package for the ubuntu OS using apt-get install option first time I stop the process, then while I try in the next time i got the following error message.
tolga@tolga-linux:~$ sudo apt-get install xchm (For example)
E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
Linux apt-get install already stop the problem

How to resolve the problem
First find out the process
#ps -e | grep apt
For these result we will get the procesid for which one it is run under backend process.
kill that process with process id.
#kill -9 processid

Then try it,
tolga@tolga-linux:~$ sudo apt-get install xchm (For example)
E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?