it seems there may be a potential memory leak in Courier service (org.sakaiproject.presence.impl.BasePresenceService).
memory analysis of a heap dump taken after 640 hours of running on 7.2 shows that a single ConcurrentHashMap takes up 72Mb of ram.
The HashMap is:
/** Stores a List of Deliveries for each address, keyed by address. */
protected Map<String, List<Delivery>> m_addresses =
new ConcurrentHashMap<String, List<Delivery>>(nLocks, 0.75f, nLocks);
I speculate that there is a condition in which elements are added to the map but never removed