The fix for bug 56698 (r1608443, r1608448) implemented an automated test for PersistenceManager. Reviewing the manager code to investigate the test failures, I see two issues:

Checks that evaluate idle time of a session in PersistenceManagerBase typically do the following:

> int timeIdle = (int) (session.getIdleTime() / 1000L);
> if (timeIdle > maxIdleBackup) { ... }

I see two errors in those two lines:

Error 1.
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The integer division performs truncation. Comparing the code with documentation, the condition there shall be

> if (timeIdle >= maxIdleBackup) { ... }

It does no matter much for a real-world configuration where the times are expected to be tens of seconds, but it matters for the test case that wants to run fast.

Error 2.
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StandardSession.getIdleTime() performs a validity check and can throw an ISE which is unexpected here. It shall be replaced with a call to session.getIdleTimeInternal().