Major Description
With long lived messages and outstanding acks, ack distribution can be sparse across data files. If a data file is in use (still has unreferenced messages, the data files containing acks for all those messages also need to be maintained to ensure a replay of the journal replays the corresponding acks. Currently it is possible that data files with no unreferenced messages but with acks pertinent to an in use data file can get deleted. The result is duplicate or relay of old messages after journal recovery (following a crash/restart)