Hi everyone, im one of the maintainers of pax wicket, and since we have upgraded to wicket 8.1 I am regularly getting this, the project I am getting this on are not using apache commons LinkedMap:
2019-01-07T09:58:04,024 | ERROR | org.ops4j.pax.wicket.util.serialization.PaxWicketObjectOutputStream | Wicket-AsyncPageStore-PageSavingThread | PaxWicketObjectOutputStream | 166 - org.ops4j.pax.wicket.service - 5.0.0 | error writing object [Page class = dk.netdesign.wallboard.frontend.pages.ViewerPage, id = 0, render count = 2848]: null java.util.ConcurrentModificationException: null at java.util.ArrayList.writeObject(Unknown Source) ~[?:?] at sun.reflect.GeneratedMethodAccessor48.invoke(Unknown Source) ~[?:?] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:?] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:?] at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeSerialData(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeObject0(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeSerialData(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeObject0(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeSerialData(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeObject0(Unknown Source) ~[?:?] at java.io.ObjectOutputStream.writeObject(Unknown Source) ~[?:?] at org.apache.commons.collections4.map.AbstractHashedMap.doWriteObject(AbstractHashedMap.java:1234) ~[?:?] at org.apache.commons.collections4.map.LinkedMap.writeObject(LinkedMap.java:124) ~[?:?] at sun.reflect.GeneratedMethodAccessor184.invoke(Unknown Source) ~[?:?] which points me to a little down the stack trace to https://github.com/ops4j/org.ops4j.pax.wicket/blob/master/service/src/main/java/org/ops4j/pax/wicket/util/serialization/PaxWicketObjectOutputStream.java#L58 Im wondering if this implemementation are wrong? I can see that Wicket are using the LinkedMap here and are wondering why it could throw ConcurrentModificationException: https://github.com/apache/wicket/blob/master/wicket-core/src/main/java/org/apache/wicket/MarkupContainer.java#L1172 (thanks for helping out) -- Best regards / Med venlig hilsen Nino Martinez
