[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-6880) Implementations of org.hibernate.type.Type contain references to non-serializable entities

[Mindaugas Žakšauskas (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-6880?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=44837#comment-44837 ] 

Mindaugas Žakšauskas commented on HHH-6880:
-------------------------------------------

Steve: Just look at the test I wrote for the linked HHH-6822
MZ: The unit test ({{SessionFactorySerializationTest}}) tests whether {{SessionFactory}} is correctly serialized. That's fine. My point was that {{o.h.t.ComponentType}} (and others) should not even *attempt* to serialize {{typeScope}} (which is of type {{o.h.t.TypeFactory.TypeScope}} and which contains reference to {{SessionFactory}}). Why serialize something what not used when deserialized (in fact, it is +*not used at all*+, but that's another matter)? In our system we need to replicate billions of Hibernate cache flush events over the network, and each unnecessary transferred byte just adds to the delay to the overall system consistency.

Steve: If you don't upgrade major libraries for point releases god have mercy on your soul...
MZ: 4.0.1 is a bugfix release to 4.0.0. We are running 3.6.7 and do not plan to upgrade to 4.X for a while. Correct me if I'm wrong, but as I understand 4.X is a major upgrade over 3.X.

Steve: as for the others, I don't think they really require response.
MZ: are you saying that having references to non-serializable objects (comparators) is OK in a serializable class ({{org.hibernate.type.SortedSetType}})?

> Implementations of org.hibernate.type.Type contain references to non-serializable entities
> ------------------------------------------------------------------------------------------
>
>                 Key: HHH-6880
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-6880
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.6.7
>         Environment: Seen this on MySQL but I believe this is environment-agnostic
>            Reporter: Mindaugas Žakšauskas
>            Assignee: Steve Ebersole
>            Priority: Critical
>              Labels: serialization
>          Time Spent: 59m
>
> This is a spin-off from
> - https://forum.hibernate.org/viewtopic.php?f=1&t=1013687&sid=e62b8ea711e4986a6ff419e3e641e2e8
> - http://stackoverflow.com/q/8404559/7345
> org.hibernate.cache.CacheKey is an object which is used for L2 cache notifications - e.g. to flush a cache on a different cluster node when a certain object has been updated.
> The problem comes from org.hibernate.cache.CacheKey carrying the type which (sometimes) happens to have a reference to objects like org.hibernate.impl.SessionFactoryImpl.
> This problem is actually not just theoretic but also causes real pain. First, it takes much longer to broadcast cache flush events. Secondly, I get this exception during deserialization of such a CacheKey: 
> java.lang.NullPointerException
>  at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
>  at org.hibernate.impl.SessionFactoryObjectFactory.getNamedInstance(SessionFactoryObjectFactory.java:159)
>  at org.hibernate.impl.SessionFactoryImpl.readResolve(SessionFactoryImpl.java:753)
>  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>  at java.lang.reflect.Method.invoke(Method.java:597)
>  at java.io.ObjectStreamClass.invokeReadResolve(ObjectStreamClass.java:1061)
>  at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1762)
>  at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
>  at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)
>  at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871)
>  at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
>  at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
>  at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)
>  at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871)
>  at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
>  at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
>  at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)
>  at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1871)
>  at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
>  at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
>  at java.io.ObjectInputStream.readUnshared(ObjectInputStream.java:441)
>  at my.class.deserializeKey(EhcacheUtils.java:35)
> I have done a quick scan through all the types, and found these problems related to their serializability:
> 1) org.hibernate.type.CollectionType, org.hibernate.type.ComponentType and subclasses of both - they use attribute "typeScope" (of type TypeFactory.TypeScope) which is assigned in the constructor and kept in the but seems to be never used. The typeScope in turn has a reference to the SessionImpl. Can it simply be removed?
> 2) org.hibernate.type.EntityType (and its subclasses) stores typeScope and only uses it in the getter, so I guess it should be safe to remove it, too.
> 3) org.hibernate.type.SortedSetType and org.hibernate.type.SortedMapType keeps a reference to the comparator, but does not enforce its serializability. It should at least throw a runtime exception in org.hibernate.mapping.Collection::getComparator if the comparator is not serializable.

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