EntityManager.merge(...) causes StackOverflowError on larger models
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Brett MeyerApril 22, 2015 at 9:14 PM
Closing rejected issues.
Former userJanuary 15, 2015 at 7:58 PM
Not a bug.
MartinHJanuary 13, 2015 at 8:23 AM
As far as I can tell, it's not an infinite loop. Granted, this is more of a scalability issue than a bug. However, seeing an industry standard tool such as Hibernate choke on a single-linked list with merely 3000 entries was pretty disappointing, so I thought that I should let you know that this is an issue. In my use case, I have to deal with arbitrary graphs with 30k to 100k nodes and arbitrary connections in between, cycles included. Increasing the JVM stack size just won't cut it.
The only possible solution that I can see right now is to perform a change in the meta model. Instead of maintaining a Set<Node> for the neighbors of a node, I would have to maintan a Set<String> that contains the node IDs of the neighbors, and resolve the neighbors in the business logic by loading them by id from the database. It's not very pretty, and it's definitly not a very ORM-style solution, but it scales to the required dimensions.
Former userJanuary 12, 2015 at 11:50 PM
Both merge and persist are recursive operations, but merge takes more memory than persist, so I wouldn't be surprised that you would hit a StackOverflowError using merge before you would see it with persist. I would also expect that increasing the size of the graph would eventually cause a StackOverflowError using persist.
Tweaking -Xss should help, provided your environment has enough memory.
I would only consider this a bug if there was an infinite loop. Is this the case?
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Former userFormer user(Deactivated)Reporter
MartinHMartinHLabels
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Details
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Former userReporter
MartinHLabels
Components
Affects versions
Priority
Major
When using a directed Graph structure model like this:
Graph, consists of set of nodes
Node, consists of set of neighbors
... and using it to create a sufficiently large closed Node Ring (about 3000 nodes), EntityManager.merge(graph) throws a StackOverflowError.
EntityManager.persist(graph) works fine. Loading via HQL works as well, only EntityManager.merge(graph) seems to be affected.
I have attached a zipped, self-contained Eclipse Project that contains a minimal test case. Just run "src/test/java/test/JUnitTest.java" as a JUnit test.
This is somewhat related to this closed bug:
https://hibernate.atlassian.net/browse/HHH-3046
The repeating part of the Stack Trace is:
at org.hibernate.engine.spi.CascadingActions$6.cascade(CascadingActions.java:277)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:350)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:293)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161)
at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:379)
at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:319)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:296)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:118)
at org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:460)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:255)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:317)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:186)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:886)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:868)