Running a modified version of the Database Opensource Test Suite (DOTS) (v1.1.1) test case ATCJ2 (auction "simulation"), available from http://sourceforge.net/project/showfiles.php?group_id=3382, resulted in an "OutOfMemoryError: Java heap space" after 57 days, 13 hours and 21 minutes.
The test run has previously been described on derby-dev: http://www.nabble.com/Long-running-testing-of-10.2.1.5-t2382591.html.
The modifications to the original test case were mainly to avoid the type of errors described in http://www.nabble.com/OutOfMemoryErrors-when-testing-Derby-with-DOTS-t1010027.html. Indeed, this is a different, yet similar error.
Heap size (both client and server JVMs) was:
The test was run against the 10.2.1.5 release candidate, but since this version does not exist in Jira, and the delta between 10.2.1.5 and the released 10.2.1.6 is minimal, 10.2.1.6 is marked as the "affects version".