Memory leak causing Nutch Server to run out of memory

My application is trying to perform continuous crawling using Nutch REST services. The application injects a seed URL and then repeats GENERATE/FETCH/PARSE/UPDATEDB sequence requested number of times (each step in the sequence is executed upon successful competition of the previous step then the whole sequence is repeated again). Here is a brief description of the job:

• Number of GENERATE/FETCH/PARSE/UPDATEDB cycles per run: 50
• 'topN' parameter value of GENERATE step in each cycle: 10
• Seed URL: http://www.cnn.com
• Regex URL filters for all jobs:
  • "-^.{1000,}$" - exclude very long URLs
  • "+." - include the rest

To monitor Nutch server I use Java VisualVM that comes with Java SDK. After each run (50 cycles of GENERATE/FETCH/PARSE/UPDATEDB) I perform garbage collection using the mentioned tool and check memory usage. My observation is that Nutch Server leaks ~25MB per run.

NOTES: I added custom HTTP DELETE services to clean job history in NutchServerPoolExecutor and remove all custom configurations from RAMConfManager after each run. So observed ~25MB memory leak is after job history/configuration cleanup.