Sonar. Hudson plugins can gather statistics with static analysis tools like PMD, Findbugs and Checkstyle, as well as calculating the code coverage of the JUnit tests. Sonar is providing all this plus many more features and can be run via a plugin from Hudson. Sonar will collect approx. 1MB of data in a database per 1000 LOC per run. Sonar should not be run more than once per day.