ConcurrentModificationException and duplicate class definition

Jiri Vanek jvanek at redhat.com
Tue Feb 16 06:19:24 UTC 2016 

On 02/15/2016 03:30 PM, Robert Marcano wrote:
> On 02/15/2016 09:54 AM, Robert Marcano wrote:


Hello!

I will e happy to help with this..but... although this is error in ITW's classlaoder - how is ITW 
involved?

It do not run JNLP file, right? How can I reproduce it?

Also - that linkage error, is it fatal? I guess so...

J.
>> Greetings. I am trying to narrow down a bug I experience only when using
>> icedtea-web JNLP implementation. It doesn't happen with closed source
>> Oracle implementation. I am using Weld (CDI on a SE environment). When
>> using default Weld configuration it do concurrent bean deployment and I
>> get:
>
> I forgot to say that this doesn't happen every time. It is reported by a few users randomly,
> apparently when the application is updated. On a developer machine it happens randomly like 1 in 20
> startups with forced updates.
>
>>
>> java.lang.LinkageError: loader (instance of
>> net/sourceforge/jnlp/runtime/JNLPClassLoader): attempted  duplicate
>> class definition for name: "com/...../ClassName" [1]
>>
>> At first I thought it was some kind on Weld bug with concurrency. I
>> disabled concurrent deployment with a Weld configuration property. Then
>> I get java.util.ConcurrentModificationException [2] inside
>> JNLPClassLoader. Weld without concurrency doesn't mean the applications
>> is not concurrent. I start Weld initialization on a separate thread
>> meanwhile the login screen is shown and the user is typing the
>> credentials, This reduce the startup time of the application for a few
>> seconds.
>>
>> I have seen a few concurrency related old fixed bugs for icedtea-web. It
>> does looks to me like another one. Any hints?
>>
>>
>> [1] When Weld concurrency is enabled
>>
>>> org.jboss.weld.exceptions.DeploymentException: loader (instance of
>>> net/sourceforge/jnlp/runtime/JNLPClassLoader): attempted  duplicate
>>> class definition for name: "com/.../Classname"
>>>     at
>>> org.jboss.weld.executor.AbstractExecutorServices.checkForExceptions(AbstractExecutorServices.java:66)
>>>
>>>
>>>     at
>>> org.jboss.weld.executor.AbstractExecutorServices.invokeAllAndCheckForExceptions(AbstractExecutorServices.java:43)
>>>
>>>
>>>     at
>>> org.jboss.weld.executor.AbstractExecutorServices.invokeAllAndCheckForExceptions(AbstractExecutorServices.java:51)
>>>
>>>
>>>     at
>>> org.jboss.weld.bootstrap.ConcurrentBeanDeployer.addClasses(ConcurrentBeanDeployer.java:62)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.BeanDeployment.createClasses(BeanDeployment.java:209)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.WeldStartup.startInitialization(WeldStartup.java:366)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.WeldBootstrap.startInitialization(WeldBootstrap.java:76)
>>>
>>>     at org.jboss.weld.environment.se.Weld.initialize(Weld.java:149)
>>>     at com.....WeldInitializer.run(Unknown Source)
>>> Caused by: java.lang.LinkageError: loader (instance of
>>> net/sourceforge/jnlp/runtime/JNLPClassLoader): attempted  duplicate
>>> class definition for name: "com/.../Classname"
>>>     at java.lang.ClassLoader.defineClass1(Native Method)
>>>     at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
>>>     at
>>> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
>>>     at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
>>>     at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
>>>     at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
>>>     at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
>>>     at java.security.AccessController.doPrivileged(Native Method)
>>>     at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.access$1601(JNLPClassLoader.java:106)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader$5.run(JNLPClassLoader.java:1800)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader$5.run(JNLPClassLoader.java:1798)
>>>
>>>     at java.security.AccessController.doPrivileged(Native Method)
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.findClass(JNLPClassLoader.java:1797)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.loadClassExt(JNLPClassLoader.java:1834)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.loadClass(JNLPClassLoader.java:1624)
>>>
>>>     at
>>> org.jboss.weld.environment.deployment.discovery.jandex.JandexClassFileInfo.loadClass(JandexClassFileInfo.java:281)
>>>
>>>
>>>     at
>>> org.jboss.weld.environment.deployment.discovery.jandex.JandexClassFileInfo.isAssignableTo(JandexClassFileInfo.java:225)
>>>
>>>
>>>     at
>>> org.jboss.weld.environment.deployment.discovery.jandex.JandexClassFileInfo.isAssignableTo(JandexClassFileInfo.java:231)
>>>
>>>
>>>     at
>>> org.jboss.weld.environment.deployment.discovery.jandex.JandexClassFileInfo.isAssignableTo(JandexClassFileInfo.java:101)
>>>
>>>
>>>     at
>>> org.jboss.weld.util.Beans.isTypeManagedBeanOrDecoratorOrInterceptor(Beans.java:519)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.FastAnnotatedTypeLoader.loadAnnotatedType(FastAnnotatedTypeLoader.java:83)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.BeanDeployer.addClass(BeanDeployer.java:97)
>>>     at
>>> org.jboss.weld.bootstrap.ConcurrentBeanDeployer$1.doWork(ConcurrentBeanDeployer.java:65)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.ConcurrentBeanDeployer$1.doWork(ConcurrentBeanDeployer.java:62)
>>>
>>>     at
>>> org.jboss.weld.executor.IterativeWorkerTaskFactory$1.call(IterativeWorkerTaskFactory.java:60)
>>>
>>>     at
>>> org.jboss.weld.executor.IterativeWorkerTaskFactory$1.call(IterativeWorkerTaskFactory.java:53)
>>>
>>>     at java.util.concurrent.FutureTask.run(FutureTask.java:262)
>>>     at
>>> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>>>
>>>     at
>>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>>>
>>>     at java.lang.Thread.run(Thread.java:744)
>>
>>
>>
>>
>> [2] when Weld concurrency is disabled
>>
>>> Caused by: java.util.ConcurrentModificationException
>>>     at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
>>>     at java.util.ArrayList$Itr.next(ArrayList.java:851)
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.getPermissions(JNLPClassLoader.java:1180)
>>>
>>>     at
>>> java.security.SecureClassLoader.getProtectionDomain(SecureClassLoader.java:206)
>>>
>>>     at
>>> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
>>>     at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
>>>     at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
>>>     at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
>>>     at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
>>>     at java.security.AccessController.doPrivileged(Native Method)
>>>     at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.access$1701(JNLPClassLoader.java:103)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader$5.run(JNLPClassLoader.java:1666)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader$5.run(JNLPClassLoader.java:1663)
>>>
>>>     at java.security.AccessController.doPrivileged(Native Method)
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.findClass(JNLPClassLoader.java:1662)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.loadClassExt(JNLPClassLoader.java:1699)
>>>
>>>     at
>>> net.sourceforge.jnlp.runtime.JNLPClassLoader.loadClass(JNLPClassLoader.java:1498)
>>>
>>>     at java.lang.Class.getDeclaredFields0(Native Method)
>>>     at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
>>>     at java.lang.Class.getDeclaredFields(Class.java:1916)
>>>     at
>>> org.jboss.weld.security.GetDeclaredFieldsAction.run(GetDeclaredFieldsAction.java:30)
>>>
>>>     at
>>> org.jboss.weld.security.GetDeclaredFieldsAction.run(GetDeclaredFieldsAction.java:22)
>>>
>>>     at java.security.AccessController.doPrivileged(Native Method)
>>>     at
>>> org.jboss.weld.annotated.slim.backed.SecurityActions.getDeclaredFields(SecurityActions.java:47)
>>>
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType$BackedAnnotatedFields.computeValue(BackedAnnotatedType.java:179)
>>>
>>>
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType$BackedAnnotatedFields.computeValue(BackedAnnotatedType.java:173)
>>>
>>>
>>>     at org.jboss.weld.util.LazyValueHolder.get(LazyValueHolder.java:35)
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType$EagerlyInitializedLazyValueHolder.<init>(BackedAnnotatedType.java:156)
>>>
>>>
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType$BackedAnnotatedFields.<init>(BackedAnnotatedType.java:173)
>>>
>>>
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType$BackedAnnotatedFields.<init>(BackedAnnotatedType.java:173)
>>>
>>>
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType.<init>(BackedAnnotatedType.java:62)
>>>
>>>     at
>>> org.jboss.weld.annotated.slim.backed.BackedAnnotatedType.of(BackedAnnotatedType.java:44)
>>>
>>>     at
>>> org.jboss.weld.resources.ClassTransformer$TransformClassToBackedAnnotatedType.load(ClassTransformer.java:83)
>>>
>>>
>>>     at
>>> org.jboss.weld.resources.ClassTransformer$TransformClassToBackedAnnotatedType.load(ClassTransformer.java:80)
>>>
>>>
>>>     at
>>> com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3527)
>>>
>>>     at
>>> com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2319)
>>>     at
>>> com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2282)
>>>
>>>     at
>>> com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2197)
>>>     at com.google.common.cache.LocalCache.get(LocalCache.java:3937)
>>>     at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3941)
>>>     at
>>> com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4824)
>>>
>>>     at
>>> org.jboss.weld.util.cache.LoadingCacheUtils.getCacheValue(LoadingCacheUtils.java:49)
>>>
>>>     at
>>> org.jboss.weld.util.cache.LoadingCacheUtils.getCastCacheValue(LoadingCacheUtils.java:74)
>>>
>>>     at
>>> org.jboss.weld.resources.ClassTransformer.getBackedAnnotatedType(ClassTransformer.java:175)
>>>
>>>     at
>>> org.jboss.weld.resources.ClassTransformer.getBackedAnnotatedType(ClassTransformer.java:194)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.FastAnnotatedTypeLoader.loadAnnotatedType(FastAnnotatedTypeLoader.java:109)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.FastAnnotatedTypeLoader.createContext(FastAnnotatedTypeLoader.java:98)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.FastAnnotatedTypeLoader.loadAnnotatedType(FastAnnotatedTypeLoader.java:87)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.BeanDeployer.addClass(BeanDeployer.java:97)
>>>     at
>>> org.jboss.weld.bootstrap.BeanDeployer.addClasses(BeanDeployer.java:135)
>>>     at
>>> org.jboss.weld.bootstrap.BeanDeployment.createClasses(BeanDeployment.java:203)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.WeldStartup.startInitialization(WeldStartup.java:375)
>>>
>>>     at
>>> org.jboss.weld.bootstrap.WeldBootstrap.startInitialization(WeldBootstrap.java:76)
>>>
>>>     at org.jboss.weld.environment.se.Weld.initialize(Weld.java:556)
>>
>

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