Sorry, I'm not able to reproduce any major memory leak, using a couple of different dbm implementations, and there is not enough information to go on.

To pursue further, you should identify:
- what platform (operating system distribution and version)
- exactly what version of Python you are using and its origins (if not provided by the operating system distribution):
    python2.7 -c 'import sys;print(sys.version)'
- a test case that shows exactly what you run and how you determine that memory is growing
- after running the test (and possibly aborting it) and the database file "blah" has been created:
    python2.7 -c 'import whichdb;print(whichdb.whichdb("blah"))'
That should show which dbm is being used.