Hazelcast: LinkageError "尝试重复定义名称的类"

问题描述 投票：0回答：1

我在我们的hazelcast集群中看到了这个错误。

代码试图在IMap上调用executeOnKey()，例如：.

    IMap<MyKey, MyCachedClass> myMap = hz.getMap("my-map");
    myMap.executeOnKey(myKey, new EntryProcessor() {
        @Override
        public Object process(Map.Entry entry) {
            return entry.getValue().setItem(item);
        }

        @Override
        public EntryBackupProcessor getBackupProcessor() {
            return null;
        }
    });

...并得到这个异常。

Exception in thread "MYTHREAD" java.lang.LinkageError: loader (instance of com/hazelcast/internal/usercodedeployment/impl/ClassSource): attempted duplicate class definition for name: "com/mycompany/model/Item$ItemEnum"
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.lang.ClassLoader.defineClass(ClassLoader.java:642)
at com.hazelcast.internal.usercodedeployment.impl.ClassSource.define(ClassSource.java:50)
at com.hazelcast.internal.usercodedeployment.impl.ClassLocator.tryToGetClassFromRemote(ClassLocator.java:163)
at com.hazelcast.internal.usercodedeployment.impl.ClassLocator.handleClassNotFoundException(ClassLocator.java:95)
at com.hazelcast.internal.usercodedeployment.impl.ClassSource.loadClass(ClassSource.java:65)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.lang.ClassLoader.defineClass(ClassLoader.java:642)
at com.hazelcast.internal.usercodedeployment.impl.ClassSource.define(ClassSource.java:50)
at com.hazelcast.internal.usercodedeployment.impl.ClassLocator.tryToGetClassFromRemote(ClassLocator.java:161)
at com.hazelcast.internal.usercodedeployment.impl.ClassLocator.handleClassNotFoundException(ClassLocator.java:95)
at com.hazelcast.internal.usercodedeployment.UserCodeDeploymentService.handleClassNotFoundException(UserCodeDeploymentService.java:89)
at com.hazelcast.internal.usercodedeployment.UserCodeDeploymentClassLoader.loadClass(UserCodeDeploymentClassLoader.java:57)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at com.hazelcast.nio.ClassLoaderUtil.tryLoadClass(ClassLoaderUtil.java:288)
at com.hazelcast.nio.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:237)
at com.hazelcast.nio.IOUtil$ClassLoaderAwareObjectInputStream.resolveClass(IOUtil.java:646)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1868)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1751)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2042)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
at java.util.ArrayList.readObject(ArrayList.java:797)
at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1170)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2178)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
at com.hazelcast.internal.serialization.impl.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:82)
at com.hazelcast.internal.serialization.impl.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:75)
at com.hazelcast.internal.serialization.impl.StreamSerializerAdapter.read(StreamSerializerAdapter.java:48)
at com.hazelcast.internal.serialization.impl.AbstractSerializationService.readObject(AbstractSerializationService.java:269)
at com.hazelcast.internal.serialization.impl.ByteArrayObjectDataInput.readObject(ByteArrayObjectDataInput.java:574)
at com.hazelcast.map.impl.operation.EntryOperation.readInternal(EntryOperation.java:263)
at com.hazelcast.spi.Operation.readData(Operation.java:728)
at com.hazelcast.internal.serialization.impl.DataSerializableSerializer.readInternal(DataSerializableSerializer.java:160)
at com.hazelcast.internal.serialization.impl.DataSerializableSerializer.read(DataSerializableSerializer.java:106)
at com.hazelcast.internal.serialization.impl.DataSerializableSerializer.read(DataSerializableSerializer.java:51)
at com.hazelcast.internal.serialization.impl.StreamSerializerAdapter.read(StreamSerializerAdapter.java:48)
at com.hazelcast.internal.serialization.impl.AbstractSerializationService.toObject(AbstractSerializationService.java:187)
at com.hazelcast.spi.impl.NodeEngineImpl.toObject(NodeEngineImpl.java:323)
at com.hazelcast.spi.impl.operationservice.impl.OperationRunnerImpl.run(OperationRunnerImpl.java:398)
at com.hazelcast.spi.impl.operationexecutor.impl.OperationThread.process(OperationThread.java:153)
at com.hazelcast.spi.impl.operationexecutor.impl.OperationThread.process(OperationThread.java:123)
at com.hazelcast.spi.impl.operationexecutor.impl.OperationThread.run(OperationThread.java:110)
at ------ submitted from ------.(Unknown Source)
at com.hazelcast.spi.impl.operationservice.impl.InvocationFuture.resolve(InvocationFuture.java:127)
at com.hazelcast.spi.impl.operationservice.impl.InvocationFuture.resolveAndThrowIfException(InvocationFuture.java:79)
at com.hazelcast.spi.impl.AbstractInvocationFuture.get(AbstractInvocationFuture.java:162)
at com.hazelcast.map.impl.proxy.MapProxySupport.executeOnKeyInternal(MapProxySupport.java:1099)
at com.hazelcast.map.impl.proxy.MapProxyImpl.executeOnKeyInternal(MapProxyImpl.java:109)
at com.hazelcast.map.impl.proxy.MapProxyImpl.executeOnKey(MapProxyImpl.java:757)
at com.mycompany.Processor.java

所以在我看来，这似乎是：

  • 'executeOnKey(item)'命令被发送到数据所在集群的'其他'节点。
  • 其他节点正在尝试反序列化'item'。
  • 其他节点找不到内部枚举'Item$ItemEnum'的类。
  • 另一个节点向UserCodeDeploymentService发出请求，以获取类定义。
  • 一旦取到类定义，它试图创建新的类，就会出现LinkageError。

我就不明白了，为什么它第一次声称找不到类，却得到了一个重复的类异常。 而且这个错误被证明很难复制。

我们确实设置了'userCodeDeployment'，允许加载远程类定义。 我们的配置是这样的。

UserCodeDeploymentConfig ucdConfig = new UserCodeDeploymentConfig();
ucdConfig.setEnabled(true);
ucdConfig.setClassCacheMode(UserCodeDeploymentConfig.ClassCacheMode.ETERNAL);
ucdConfig.setProviderMode(UserCodeDeploymentConfig.ProviderMode.LOCAL_AND_CACHED_CLASSES);
config.setUserCodeDeploymentConfig(ucdConfig);

所以它看起来像是在做我所期望的事情，即获取一个远程类定义 因为它在本地找不到它。 只是不知道为什么会出现异常。

hazelcast hazelcast-imap
1个回答
1
投票

最终解决了这个问题。

一个简单的例子。

  • 假设有两个Hazelcast节点。 两个节点都开启了userCodeDeployment。(能够通过线缆共享类定义。)
  • 节点1在它的classpath上有MyClass，节点2有 不.
  • MyClass的定义，注意内部枚举（我认为内部枚举可以换成内部类，会发生同样的事情）。
public class MyClass implements Serializable {

    private final InnerEnum enumVal;

    public MyClass(InnerEnum enumVal) {
        this.enumVal = enumVal;
    }

    public enum InnerEnum {
        ONE, TWO, THREE;
    }
}

在节点1上，运行以下代码。

hz.getMap("myClassMap").put("myClassKey", new MyClass(MyClass.InnerEnum.ONE));
hz.getMap("myInnerEnumMap").put("myInnerEnumKey", MyClass.InnerEnum.TWO);

然后，在节点2上，运行以下代码。

System.out.println(hz.getMap("myInnerEnumMap").get("myInnerEnumKey"));
System.out.println(hz.getMap("myClassMap").get("myClassKey"));

在Node 2上，我看到了以下的记录：

[TRACE] ClassLocator Loaded class com.mycompany.MyClass$InnerEnum from Member [myhost]:5701 - cc0b2872-7f5b-484b-a40f-7c7ba1fdc165
TWO
[TRACE] ClassLocator Loaded class com.mycompany.MyClass from Member [myhost]:5701 - cc0b2872-7f5b-484b-a40f-7c7ba1fdc165

Exception in thread "main" java.lang.LinkageError: loader (instance of  com/hazelcast/internal/usercodedeployment/impl/ClassSource): attempted  duplicate class definition for name: "com/mycompany/MyClass$InnerEnum"
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:642)
    at com.hazelcast.internal.usercodedeployment.impl.ClassSource.define(ClassSource.java:50)
    at com.hazelcast.internal.usercodedeployment.impl.ClassLocator.tryToGetClassFromRemote(ClassLocator.java:163)
    at com.hazelcast.internal.usercodedeployment.impl.ClassLocator.handleClassNotFoundException(ClassLocator.java:95)
    at com.hazelcast.internal.usercodedeployment.UserCodeDeploymentService.handleClassNotFoundException(UserCodeDeploymentService.java:89)
    at com.hazelcast.internal.usercodedeployment.UserCodeDeploymentClassLoader.loadClass(UserCodeDeploymentClassLoader.java:57)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at com.hazelcast.nio.ClassLoaderUtil.tryLoadClass(ClassLoaderUtil.java:288)
    at com.hazelcast.nio.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:237)
    at com.hazelcast.nio.IOUtil$ClassLoaderAwareObjectInputStream.resolveClass(IOUtil.java:646)
    at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1868)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1751)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2042)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
    at com.hazelcast.internal.serialization.impl.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:82)
    at com.hazelcast.internal.serialization.impl.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:75)
    at com.hazelcast.internal.serialization.impl.StreamSerializerAdapter.read(StreamSerializerAdapter.java:48)
    at com.hazelcast.internal.serialization.impl.AbstractSerializationService.toObject(AbstractSerializationService.java:187)
    at com.hazelcast.map.impl.proxy.MapProxySupport.toObject(MapProxySupport.java:1245)
    at com.hazelcast.map.impl.proxy.MapProxyImpl.get(MapProxyImpl.java:120)
    at com.mycompany.main(Node2.java:74)

所以..:

  1. 节点2首先试图获取并显示MyClass$InnerEnum的实例。 它通过 hazelcast 从 Node 1 获取 InnerEnum 类定义。
  2. 节点2然后试图获取并显示MyClass的实例。 它从节点1获取MyClass类的定义。
  3. 然后，Hazelcast循环浏览MyClass的内部类（其中只包含InnerEnum），并要求类加载器定义它们，而不检查它们是否已经存在。

参见（来自Hazelcast 3.11.1）com.hazelcast.internal.usercodedeployment.impl.ClassLocator:160。

Map<String, byte[]> innerClassDefinitions = classData.getInnerClassDefinitions();
classSource.define(name, classData.getMainClassDefinition());
for (Map.Entry<String, byte[]> entry : innerClassDefinitions.entrySet()) {
    classSource.define(entry.getKey(), entry.getValue());
}

在我们的案例中，最简单的解决方案是将InnerEnum作为一个顶层Enum拉出来。

0
投票

试着将EntryProcessor创建为一个静态类或顶层类，并通过 项 在其构造函数中明确表示。希望这能解决这个问题。

JVM对动态类的加载可能会有点棘手，这就是UserCodeDeployment所做的事情。

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