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I saw this error both on the build server and in the IDE: java.lang.NullPointerException at java.util.LinkedList.writeObject(LinkedList.java:755) 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:585) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:917) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1339) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1290) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1079) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1375) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1347) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1290) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1079) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1375) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1347) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1290) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1079) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:302) at org.eclipse.rap.rwt.testfixture.Fixture.serialize(Fixture.java:482) at org.eclipse.rap.rwt.testfixture.Fixture.serializeAndDeserialize(Fixture.java:494) at org.eclipse.swt.widgets.DisplaySerialization_Test.serializeAndDeserialize(DisplaySerialization_Test.java:248) at org.eclipse.swt.widgets.DisplaySerialization_Test.testTimerExecIsSerializable(DisplaySerialization_Test.java:218) 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:585) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:243) at junit.framework.TestSuite.run(TestSuite.java:238) at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
I tweaked the timing of the test participants. Changes are in CVS HEAD. Please reopen if the problem reappears.
The test still fails on the build server when checking out from HEAD. I'm positive that the build gets the current version.
Created attachment 204383 [details] Proposed fix and test
The exception was caused by concurrent access to the 'tasks' list from the main thread (the one doing the serialization) and the timer thread. The fix was to synchronize access to the 'tasks' list during seriaization. Changes are in CVS HEAD.
