This also applies to FindBugs, PMD etc.

If I have 100 lines of codes and 10 warnings, it's much worse than having 100000
lines of code and 10 warnings.

So it's arbitrary to configure a certain number of warnings as thresholds. The
thresholds should be rather expressed as percentage of the lines of code.

This plugin could be used for LOC:
http://wiki.jenkins-ci.org/display/JENKINS/SLOCCount+Plugin