GenShen: Limit tenuring with minimum time since allocation

In some cases, engineers responsible for configuration of a GenShen deployment can reduce premature promotions by setting a minimum amount of time the object must live before it is eligible for promotion.

In the case that the typical time for a transaction is known to be N ms, with some transactions contributing to more permanent state (existing in old generation), set the minimum time for promotion to be N ms.

This will cause GenShen to delay promotion of the object until the object has lived the specified amount of time, even if the tenuring age has been reached. Note that object ages may be incremented more quickly than "normal" during workload spikes that require more frequent GC cycles.