If you don't mind the handle being rather large, make the sequence number 64 bits, and store it alongside the index. 2^64 nanoseconds in years = 585... computer

If you don't mind the handle being rather large, make the sequence number 64 bits, and store it alongside the index. 2^64 nanoseconds in years = 585... computers just aren't fast enough to wrap it around in any reasonable time frame. Depending on how many index bits you want, you might be good with only 64 bits in total. 2^56 ns in years = 2.3; 2^52 ns in days = 52; 2^48 ns in days = 3.3; and so on. All of these figures are worst case scenarios, anyway. Your program probably simply can't actually be made to allocate objects at that rate.