ClassCastException when reloading session

Dalton · June 4, 2009, 1:01am

Hi.

I often have this ClassCastException when Eclipse reloads the Tomcat session after I had saved a file. The execution seems to continue normally after this exception. I’ve opened the com.vaadin.data.util.MethodProperty source code suspecting it could be some sort of bad spelling, but I can’t find anything related to the strange typecasting to “[Ljava.lang.Class” as alleged by the exception.

I did not fill a bug report because I’m not sure this is a Vaadin bug. Could somebody confirm this?

Thanks in advance.


SEVERE: Exception loading sessions from persistent storage
java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.Class;
	at com.vaadin.data.util.MethodProperty.readObject(MethodProperty.java:138)
	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.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
	at java.util.HashMap.readObject(HashMap.java:1030)
	at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.HashMap.readObject(HashMap.java:1030)
	at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.defaultReadObject(ObjectInputStream.java:480)
	at com.vaadin.data.util.BeanItemContainer.readObject(BeanItemContainer.java:58)
	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.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.LinkedList.readObject(LinkedList.java:964)
	at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.LinkedList.readObject(LinkedList.java:964)
	at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.LinkedList.readObject(LinkedList.java:964)
	at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.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.defaultReadObject(ObjectInputStream.java:480)
	at com.vaadin.event.ListenerMethod.readObject(ListenerMethod.java:106)
	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.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
	at java.util.HashSet.readObject(HashSet.java:291)
	at sun.reflect.GeneratedMethodAccessor34.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.HashMap.readObject(HashMap.java:1030)
	at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.LinkedList.readObject(LinkedList.java:964)
	at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at java.util.HashMap.readObject(HashMap.java:1029)
	at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
	at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)
	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.readObject(ObjectInputStream.java:351)
	at org.apache.catalina.session.StandardSession.readObject(StandardSession.java:1441)
	at org.apache.catalina.session.StandardSession.readObjectData(StandardSession.java:942)
	at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:394)
	at org.apache.catalina.session.StandardManager.load(StandardManager.java:321)
	at org.apache.catalina.session.StandardManager.start(StandardManager.java:637)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4351)
	at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3099)
	at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:404)
	at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1309)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590)
	at java.lang.Thread.run(Thread.java:619)

default · June 4, 2009, 5:32pm

Hi,

This sounds like a bug in the serialization/deserialization of MethodProperty. Please create a ticket about this at
http://dev.vaadin.com

Artur

Dalton · June 5, 2009, 1:34am

OK, created the ticket #3051 with even further information. http://dev.vaadin.com/ticket/3051

Joonas · June 6, 2009, 12:52am

Thanks for the bug report Dalton. Artur said that he already corrected the problem and will commit it as soon as it is tested.

There is another known serialization bug: http://dev.vaadin.com/ticket/3015

These will be corrected shortly.

Artur · June 9, 2009, 10:55am

Both serialization bugs are fixed in the latest nightly version.

Note that if you do not want/need session serialization you can turn it off in Tomcat. In conf/context.xml:

<!-- Uncomment this to disable session persistence across Tomcat restarts -->
<!--
<Manager pathname="" />
-->

Joonas · June 9, 2009, 11:16am

How is GAE working after these fixes?

Artur · June 9, 2009, 1:08pm

Some applications are working fine (like the calculator), while others do not. There are certain problems with GAE that I do not see how we could solve, for instance that de-serialization of a DateField just does not work because of a problem in GAE (
#3057

http://code.google.com/p/googleappengine/issues/detail?id=1290
). Another big problem is the missing session synchronization (
#3058
) which is hard for anyone but Google to solve in a sensible way.

Right now I am getting a lot of “java.util.ConcurrentModificationException: too much contention on these datastore entities. please try again.” errors. Probably related to my test application and the missing session synchronization but could be yet another problem.

If you are lucky and have a suitable application it might work, go ahead and try! Be sure though not to use any Object() as identifiers etc as Object is not serializable.

Dalton · June 9, 2009, 9:20pm

Thank you very much for the great job. I’ll do the changes to Tomcat conf/contents.xml as recomended. I think I will only need serialization of the Vaadin app in the future, perhaps when we can use the Google AppEngine.