Hello, I'm in need of some help about how to fix this memory leak at HSEARCH-310 in ScrollableResultsImpl of Search, there currently is:
* an internal cache of all loaded EntityInfo * an internal cache of all loaded managed Entities Both caches are never emptied during the scrolling; the implementation is loading a batch-sized list each time an entity is requested which was not loaded before and adds new objects to the caches. We had said to use some Soft ReferenceMap to fix this, but actually we should evict the loaded entities which where not requested from the client code, or I'll still be leaking memory in Hibernate's persistence context. I expect the most frequent use case for a ScrollableResults should be to iterate at will and periodically evict objects in the client code; Still the client could skip some entities we loaded by batching. At first I thought to keep track of which references were used and evict the other ones, but this isn't a good solution as the client could be loading some entities by other means (i.e. another query) and won't be happy if I'm evicting some random entities: I don't have enough information to know for sure what to evict and what is going to be used later. Also a bug, consequence of current implementation, is that if you get an object, then you evict it, and then try scrollable.get() you don't get an attached object but again the evicted instance; as a client of the Hibernate library I expect all objects I ask for to be attached by default. My idea to fix this should be something like: 1) load the batch 2) evict them all 3) and then load one by one as requested, relying on the second level cache (I suppose point 1 should have warmed it) But this has other flaws.. like I should not evict (2) those objects already existing in the persistence context. Ideally I should avoid to preload objects already present in the persistence context; I am considering to look in the session.persistenceContext.entitiesByKey map to only load+evict by batch those entities not already managed. Is there some way to populate the second level cache skipping the actual load in the persistence context? Should I keep my own "soft map cache" in the scroll implementation anyway, and somehow detach and reattach them as needed? Am I missing some trivial better solution, or is my solution not going to work at all? thanks, Sanne _______________________________________________ hibernate-dev mailing list hibernate-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/hibernate-dev
