In our experience dealing with this issue we noticed that using method references works well (enough), and if that fails falling back to anon-inner classes (or nested or...).
It sucks because it is difficult to reverse engineer which lambda is unable to be deserialized because of how deserialization works. IIRC I've updated the serialization/deserialization protocol of Wicket by adding a header for which page class is serialized/deserialized so that at least you know which page class it was that contains the lambda (am unable to find the code though) Martijn On Tue, Apr 29, 2025 at 8:06 AM Tobias Gierke < [email protected]> wrote: > Hi, > > Our company is a long time Wicket user on a large code base (10+ years, > >600k loc) and ever since lambdas got introduced in JDK 8, our Wicket > applications have occasionally been plagued by random crashes during > Wicket Page deserialization like this: > > |Caused by: java.lang.reflect.InvocationTargetException at > java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:109) > > at java.base/java.lang.reflect.Method.invoke(Method.java:580) at > com.vodecc.voipmng.boundary.wicket.WicketApplication$5.lambda$get$0(WicketApplication.java:864) > > ... 63 more Caused by: java.lang.ClassCastException: cannot assign > instance of java.lang.invoke.SerializedLambda to field > <someClass>.<someFieldWithTypeIModel> of type > org.apache.wicket.model.IModel at > java.base/java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2096) > > at > java.base/java.io.ObjectStreamClass$FieldReflector.checkObjectFieldValueTypes(ObjectStreamClass.java:2060) > > at > java.base/java.io.ObjectStreamClass.checkObjFieldValueTypes(ObjectStreamClass.java:1349) > > at > java.base/java.io.ObjectInputStream$FieldValues.defaultCheckFieldValues(ObjectInputStream.java:2697) > > at > java.base/java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2498) > > at > java.base/java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2284) > > at > java.base/java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1762) > > at > java.base/java.io.ObjectInputStream$FieldValues.<init>(ObjectInputStream.java:2618) > > at > java.base/java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2469) > > at > java.base/java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2284) > > at > java.base/java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1762) > > at > java.base/java.io.ObjectInputStream.readObject(ObjectInputStream.java:540) > > at > java.base/java.io.ObjectInputStream.readObject(ObjectInputStream.java:498) > > at java.base/java.util.ArrayList.readObject(ArrayList.java:981) at > java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) > > at java.base/java.lang.reflect.Method.invoke(Method.java:580) | > > The offending member field in this particular crash has a type of > 'IModel<String>'. > > With "random crashes" I mean that the same code sometimes works and > sometimes crashes, seemingly dependent on the order in which > (capturing?) lambdas are created or called. > > I did spent some time looking into this and found quite a few > *unresolved* JDK bugs related to ClassCastExceptions during lambda > serialization: > > https://bugs.openjdk.org/browse/JDK-8154236 > https://bugs.openjdk.org/browse/JDK-8208752 > https://bugs.openjdk.org/browse/JDK-8275387 > https://bugs.openjdk.org/browse/JDK-8174864 > https://bugs.openjdk.org/browse/JDK-8174865 > > A comment on JDK-8275387 seemed especially enlightening: "The root cause > is always the same: java.lang.invoke.SerializedLambda can not hold > enough information to correctly identify the which lambda should be > (de-)serialized". This all points to > https://bugs.openjdk.org/browse/JDK-8174864 as the root of the problem. > That ticket mentions that currently, lambda serialization is a lossy > transformation since only the first invocation of any unique > "serialization key" will work (which would explain the randomness we > observed). > > We currently "fix" our crashes by using anonymous classes instead of > lambda expressions but obviously this is not ideal - especially since > (given enough indirections) it's quite hard to find out where the lambda > causing the deserialization crash originated from. > > Cheers, > Tobias > > || > -- Become a Wicket expert, learn from the best: http://wicketinaction.com
