How to debug Flink Task Issues - scala

Hi I am trying to run a flink scala application which reads from kafka apply some lookup transformations and then writes to kafka.
Flink Version 1.12.1
I tested it in local and it works fine.
But when I try to run it on cluster using native kubernetes integration I see weird errors like below.
The cluster also looks fine, because I tried to run a wordcount app on the cluster and it worked fine.
The exception is not clear and also the stacktrace shows the taskmanager stack trace and hence no idea where in the application the problem could be. Could this be a serialization issue? Is there a way to debug such issues and find the actual point in application code where there is a problem?
org.apache.flink.streaming.runtime.tasks.StreamTaskException: Could not instantiate serializer.
at org.apache.flink.streaming.api.graph.StreamConfig.getTypeSerializerOut(StreamConfig.java:216) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.runtime.tasks.OperatorChain.createStreamOutput(OperatorChain.java:664) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.runtime.tasks.OperatorChain.createChainOutputs(OperatorChain.java:250) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.runtime.tasks.OperatorChain.<init>(OperatorChain.java:160) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.runtime.tasks.StreamTask.beforeInvoke(StreamTask.java:485) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:533) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:722) [flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:547) [flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at java.lang.Thread.run(Unknown Source) [?:?]
Caused by: java.io.IOException: unexpected exception type
at java.io.ObjectStreamClass.throwMiscException(Unknown Source) ~[?:?]
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readSerialData(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readArray(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.defaultReadFields(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readSerialData(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject(Unknown Source) ~[?:?]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:576) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:562) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:550) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.readObjectFromConfig(InstantiationUtil.java:511) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.api.graph.StreamConfig.getTypeSerializerOut(StreamConfig.java:214) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
... 8 more
Caused by: java.util.concurrent.ExecutionException: java.lang.ClassNotFoundException: __wrapper$1$7aa8fcbe22114421a688e120fcde1df7.__wrapper$1$7aa8fcbe22114421a688e120fcde1df7$
at org.apache.flink.shaded.guava18.com.google.common.util.concurrent.AbstractFuture$Sync.getValue(AbstractFuture.java:299) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.util.concurrent.AbstractFuture$Sync.get(AbstractFuture.java:286) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:116) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:137) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$LoadingValueReference.waitForValue(LocalCache.java:3557) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$Segment.waitForLoadingValue(LocalCache.java:2302) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2289) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2197) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache.get(LocalCache.java:3937) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4739) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer$.compileCbf(TraversableSerializer.scala:184) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer.compileCbf(TraversableSerializer.scala:51) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer.readObject(TraversableSerializer.scala:72) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at jdk.internal.reflect.GeneratedMethodAccessor77.invoke(Unknown Source) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:?]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:?]
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readSerialData(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readArray(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.defaultReadFields(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readSerialData(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject(Unknown Source) ~[?:?]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:576) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:562) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:550) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.readObjectFromConfig(InstantiationUtil.java:511) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.api.graph.StreamConfig.getTypeSerializerOut(StreamConfig.java:214) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
... 8 more
Caused by: java.lang.ClassNotFoundException: __wrapper$1$7aa8fcbe22114421a688e120fcde1df7.__wrapper$1$7aa8fcbe22114421a688e120fcde1df7$
at scala.reflect.internal.util.AbstractFileClassLoader.findClass(AbstractFileClassLoader.scala:64) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:?]
at java.lang.Class.forName0(Native Method) ~[?:?]
at java.lang.Class.forName(Unknown Source) ~[?:?]
at scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$ToolBoxGlobal.compile(ToolBoxFactory.scala:261) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at scala.tools.reflect.ToolBoxFactory$ToolBoxImpl.$anonfun$compile$13(ToolBoxFactory.scala:433) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at scala.tools.reflect.ToolBoxFactory$ToolBoxImpl$withCompilerApi$.apply(ToolBoxFactory.scala:359) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at scala.tools.reflect.ToolBoxFactory$ToolBoxImpl.compile(ToolBoxFactory.scala:426) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer$LazyRuntimeCompiler.compileCbfInternal(TraversableSerializer.scala:230) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer$LazyRuntimeCompiler.call(TraversableSerializer.scala:220) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer$LazyRuntimeCompiler.call(TraversableSerializer.scala:216) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$LocalManualCache$1.load(LocalCache.java:4742) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3527) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2319) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2282) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2197) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache.get(LocalCache.java:3937) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.shaded.guava18.com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4739) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer$.compileCbf(TraversableSerializer.scala:184) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer.compileCbf(TraversableSerializer.scala:51) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.api.scala.typeutils.TraversableSerializer.readObject(TraversableSerializer.scala:72) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at jdk.internal.reflect.GeneratedMethodAccessor77.invoke(Unknown Source) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:?]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:?]
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readSerialData(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readArray(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.defaultReadFields(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readSerialData(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject0(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject(Unknown Source) ~[?:?]
at java.io.ObjectInputStream.readObject(Unknown Source) ~[?:?]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:576) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:562) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:550) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.util.InstantiationUtil.readObjectFromConfig(InstantiationUtil.java:511) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
at org.apache.flink.streaming.api.graph.StreamConfig.getTypeSerializerOut(StreamConfig.java:214) ~[flink-dist_2.12-1.12-SNAPSHOT.jar:1.12-SNAPSHOT]
... 8 more```


My guess was the problem was with order of classloading.
I was trying to deploying in application mode. Before I had my user code jar and dependent libs in /opt/flink/usrlib.
I tried to follow this guide
https://ci.apache.org/projects/flink/flink-docs-release-1.13/docs/deployment/resource-providers/native_kubernetes/#application-mode
and used /usrlib to put it in the jars. I was seeing the error above.
Now I changed to /opt/flink/lib and user code and dependencies with flink libs are in the same dir inside the docker image.
Changed
COPY .dist/poc-flink-0.0.1.jar $FLINK_HOME/usrlib/poc-flink.jar
to
COPY .dist/poc-flink-0.0.1.jar $FLINK_HOME/lib/poc-flink.jar
So the same classloader is used.
And it solved the problem.

Related

ConcurrentModificationException when serializing a page in Wicket

In my application, a ConcurrentModificationException is sporadically thrown by Wicket when serializing a page. Unfortunately, I can't see what is causing it. Does anyone have an idea or how can I find the cause? I use Wicket 8.8.0. I don't use any maps in the MyPage page.
JavaSerializer (Wicket-AsyncPageStore-PageSavingThread) > error writing object [Page class = MyPage, id = 38, render count = 1822]: null
java.util.ConcurrentModificationException: null
at org.apache.commons.collections4.map.AbstractLinkedMap$LinkIterator.nextEntry(AbstractLinkedMap.java:574) ~[commons-collections4-4.4.jar:4.4]
at org.apache.commons.collections4.map.AbstractLinkedMap$LinkMapIterator.next(AbstractLinkedMap.java:369) ~[commons-collections4-4.4.jar:4.4]
at org.apache.commons.collections4.map.AbstractHashedMap.doWriteObject(AbstractHashedMap.java:1245) ~[commons-collections4-4.4.jar:4.4]
at org.apache.commons.collections4.map.LinkedMap.writeObject(LinkedMap.java:134) ~[commons-collections4-4.4.jar:4.4]
at jdk.internal.reflect.GeneratedMethodAccessor1223.invoke(Unknown Source) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1016) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1487) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1543) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1500) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345) ~[?:?]
at java.util.ArrayList.writeObject(ArrayList.java:897) ~[?:?]
at jdk.internal.reflect.GeneratedMethodAccessor86.invoke(Unknown Source) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1016) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1487) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1543) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1500) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345) ~[?:?]
at java.util.ArrayList.writeObject(ArrayList.java:897) ~[?:?]
at jdk.internal.reflect.GeneratedMethodAccessor86.invoke(Unknown Source) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1016) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1487) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1543) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1500) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1543) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1500) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345) ~[?:?]
at java.util.ArrayList.writeObject(ArrayList.java:897) ~[?:?]
at jdk.internal.reflect.GeneratedMethodAccessor86.invoke(Unknown Source) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1016) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1487) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1369) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1165) ~[?:?]
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1543) ~[?:?]
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1500) ~[?:?]
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1423) ~[?:?]
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1169) ~[?:?]
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345) ~[?:?]
at org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:368) ~[wicket-core-8.8.0.jar:8.8.0]
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:341) ~[?:?]
at org.apache.wicket.serialize.java.JavaSerializer.serialize(JavaSerializer.java:82) ~[wicket-core-8.8.0.jar:8.8.0]
at org.apache.wicket.pageStore.AbstractPageStore.serializePage(AbstractPageStore.java:133) ~[wicket-core-8.8.0.jar:8.8.0]
at org.apache.wicket.pageStore.DefaultPageStore.createSerializedPage(DefaultPageStore.java:281) ~[wicket-core-8.8.0.jar:8.8.0]
at org.apache.wicket.pageStore.DefaultPageStore.storePage(DefaultPageStore.java:61) ~[wicket-core-8.8.0.jar:8.8.0]
at org.apache.wicket.pageStore.AsynchronousPageStore$PageSavingRunnable.run(AsynchronousPageStore.java:208) ~[wicket-core-8.8.0.jar:8.8.0]
at java.lang.Thread.run(Thread.java:829) ~[?:?]

Firstly update to Wicket 8.14.0, there have been fixes for page serialization.

.mexa64 file doesn't execute

I have created a mex file but when I try to execute it I get this error in the command line:
java.lang.UnsatisfiedLinkError: no nativeservices in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at com.mathworks.services.Prefs.<clinit>(Prefs.java:167)
at com.mathworks.fatalexit.FatalExitFrame.<init>(FatalExitFrame.java:137)
at com.mathworks.fatalexit.FatalExitFrame$13.run(FatalExitFrame.java:770)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkError: com.mathworks.services.Prefs.nativeGetPreferencesDirectory()Ljava/lang/String;
at com.mathworks.services.Prefs.nativeGetPreferencesDirectory(Native Method)
at com.mathworks.services.Prefs.getPropertyDirectory(Prefs.java:198)
at com.mathworks.services.Prefs.load(Prefs.java:254)
at com.mathworks.services.Prefs.<clinit>(Prefs.java:174)
at com.mathworks.fatalexit.FatalExitFrame.<init>(FatalExitFrame.java:137)
at com.mathworks.fatalexit.FatalExitFrame$13.run(FatalExitFrame.java:770)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Killed
I am using Ubuntu 16.04 and MatlabR2016b with an official license. I am new to ubuntu and to .mex files so I don't really know what's going on.

This thread looks similar. From what it seems to me, your path doesn't have the required classfile nativeservices.

Pong game with graphics class and inheritance issue

I've got this lab for a class that creates a pong-like game and I've put the .java files for this lab accordingly on pastebin at the following links:
Ball.java: http://pastebin.com/VMg75i8U
Block.java: http://pastebin.com/T7GCTh4z
BallTestTwo.java: http://pastebin.com/gZgR8d2J
Tester.java: http://pastebin.com/fG5f5zZR
Locatable.java: http://pastebin.com/GE77PLJk
My issue is that I've got the blocks working just fine, as in I can run Tester.java with the ball line commented out and get my desired result. However, when I run it with the ball line uncommented, I get errors and just a blank white canvas.
Here are links to word docs of the lab descriptions if you need clarification on what the end result should be. https://docs.google.com/file/d/0B_ifaCiEZgtcTVFPX0t2Mzhzczg/edit?usp=sharing
https://docs.google.com/file/d/0B_ifaCiEZgtcMFVWYXIxdjZsdDQ/edit?usp=sharing
EDIT
The errors I'm receiving are these forever repeated until I force terminate the program:
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at BallTestTwo.paint(BallTestTwo.java:42)
at BallTestTwo.update(BallTestTwo.java:37)
at sun.awt.RepaintArea.updateComponent(Unknown Source)
at sun.awt.RepaintArea.paint(Unknown Source)
at sun.awt.windows.WComponentPeer.handleEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

GWT Deploying to Google has encountered a fault

Got an error I can't fix. Looks like a memory issue but the stack trace is kind of looping as if the is an infinite loop in the compilation?
Running Eclipse Juno
Working with Google App engine.
I get an error when I try to deploy one app to GAE however another Google App Engine app works.
Errors I see:
GWT compilation failed
The site.xml file downloaded from the update site does not contain any elements with an id of 'com.google.appengine.eclipse.sdkbundle.e42.feature'. Unable to determine if there are updates available.
eclipse.buildId=M20120914-1800
java.version=1.7.0_01
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments: -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product
Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product -data C:\Users\myuser\workspacejuno -product org.eclipse.epp.package.jee.product
[ERROR] Failure in unit cache map load.
And the complete stack dump/trace:
[ERROR] Failure in unit cache map load.
java.util.concurrent.ExecutionException: java.lang.StackOverflowError
at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)
at com.google.gwt.dev.javac.PersistentUnitCache.awaitUnitCacheMapLoad(PersistentUnitCache.java:466)
at com.google.gwt.dev.javac.PersistentUnitCache.find(PersistentUnitCache.java:391)
at com.google.gwt.dev.javac.CompilationStateBuilder.addArchive(CompilationStateBuilder.java:365)
at com.google.gwt.dev.ArchivePreloader.preloadArchives(ArchivePreloader.java:65)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:243)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:229)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:141)
at com.google.gwt.dev.Compiler.run(Compiler.java:232)
at com.google.gwt.dev.Compiler.run(Compiler.java:198)
at com.google.gwt.dev.Compiler$1.run(Compiler.java:170)
at com.google.gwt.dev.CompileTaskRunner.doRun(CompileTaskRunner.java:88)
at com.google.gwt.dev.CompileTaskRunner.runWithAppropriateLogger(CompileTaskRunner.java:82)
at com.google.gwt.dev.Compiler.main(Compiler.java:177)
Caused by: java.lang.StackOverflowError
at java.io.ObjectInputStream$PeekInputStream.peek(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.readBlockHeader(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.refill(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.read(Unknown Source)
at java.io.ObjectInputStream.read(Unknown Source)
at java.io.InputStream.read(Unknown Source)
at com.google.gwt.dev.util.DiskCache.transferFromStream(DiskCache.java:159)
at com.google.gwt.dev.util.DiskCacheToken.readObject(DiskCacheToken.java:87)
at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
[loops this a few time, sorry could not post it all, its too long.
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.skipCustomData(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.defaultReadObject(Unknown Source)
at com.google.gwt.dev.javac.CachedCompilationUnit.readObject(CachedCompilationUnit.java:204)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
onStateBuilder.java:466)
at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:388)
at com.google.gwt.dev.cfg.ModuleDef.getCompilationState(ModuleDef.java:373)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:246)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:229)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:141)
at com.google.gwt.dev.Compiler.run(Compiler.java:232)
at com.google.gwt.dev.Compiler.run(Compiler.java:198)
at com.google.gwt.dev.Compiler$1.run(Compiler.java:170)
at com.google.gwt.dev.CompileTaskRunner.doRun(CompileTaskRunner.java:88)
at com.google.gwt.dev.CompileTaskRunner.runWithAppropriateLogger(CompileTaskRunner.java:82)
at com.google.gwt.dev.Compiler.main(Compiler.java:177)

It's possibly related to a corrupted cache. Delete your gwt-UnitCache folder. If that doesn't work, delete your AppData\Local\Temp files as well (if under Windows) since there are many gwt-generated files there.

Forgive if it is too obvious or out of topic, but did you try to set or modify compiler directive: jvmarg -Xss ?
Something like <jvmarg value="-Xss16M"/> in your build.xml file may help here.

I am trying to send object of custom class through sockets, but It throws the "java.io.NotSerializableException"

The following is the custom class, whose object I am trying to pass:
package dataEx;
import java.io.Serializable;
import java.util.*;
public class dataToExchange implements Serializable
{
public Integer frameIndex;
public Integer xOffsetTank;
}
The relevant client code, where the data is an object I am trying to pass,through writeObject method:
dataToExchange data=new dataToExchange() ;
data.frameIndex=2;
data.xOffsetTank=23;
output.writeObject(data);
The server receiving the object and printing
data_recv=(dataToExchange)input.readObject();
System.out.println(data_recv.xOffsetTank);
The stacktrace:
java.io.NotSerializableException: dataEx.proclient$dataToExchange
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at dataEx.proclient.SendTheChange(proclient.java:283)
at dataEx.proclient.keyDown(proclient.java:256)
at java.awt.Component.handleEvent(Unknown Source)
at java.awt.Component.postEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(Unknown Source)
at java.net.SocketOutputStream.write(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.drain(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(Unknown Source)
at java.io.ObjectOutputStream.writeFatalException(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at dataEx.proclient.SendTheChange(proclient.java:283)
at dataEx.proclient.keyDown(proclient.java:256)
at java.awt.Component.handleEvent(Unknown Source)
at java.awt.Component.postEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(Unknown Source)
at java.net.SocketOutputStream.write(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.drain(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(Unknown Source)
at java.io.ObjectOutputStream.writeNonProxyDesc(Unknown Source)
at java.io.ObjectOutputStream.writeClassDesc(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeFatalException(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at dataEx.proclient.SendTheChange(proclient.java:283)
at dataEx.proclient.keyDown(proclient.java:256)
at java.awt.Component.handleEvent(Unknown Source)
at java.awt.Component.postEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Wrong class. Check the exception again. You are trying to serialize a class called 'dataToExchange' whose definition is nested inside the class 'proclient', and which isn't Serializable. You have overlooked that you have two classes with the same name, which is hereby demonstrated to be a bad idea.