Hazelcast 类在 EntryExpiredListener 上未找到异常

Question

由于使用 EntryExpiredListener 时未找到类，我收到了序列化异常。

我创建了一个测试 jar 并缩小了问题范围。

Test jar 包含 TestService、CacheKey 和 CacheValue。 TestService 将键类型 CacheKey 和值类型 CacheValue 插入到 IMap。 它注册了一个 EntryExpiryListener 来监听插入的条目是否过期。

TestService 代码很简单：

hazelcastService.put(
        new CacheKey("11", "12345",  "678910", 1624174140000L),
        new CacheValue(new HashMap<>())); // ttl is set to 30 sec

Collection<HazelcastInstance> instances = HazelcastClient.getAllHazelcastClients();
Optional<HazelcastInstance> instance = instances.stream().findAny();
if (!instance.isPresent()) {
    throw new IllegalStateException("Can not find Hazelcast instance!");
}
// HazelcastInstance is created by framework component
IMap<CacheKey, CacheValue> cacheMap = instance.get().getMap(cacheName);

cacheMap.addEntryListener((EntryExpiredListener<CacheKey, CacheValue>) event -> {
    CacheKey key = event.getKey();
    CacheValue val = event.getOldValue();
}, true);

public class CacheKey implements Serializable {
    private static final long serialVersionUID = 123412453256L;
    private final String type;
    private final String field1;
    private final String field2;
    private final long timestamp;
    
    // constructor, getters

public class CacheValue implements Serializable {
    private static final long serialVersionUID = 658933453256L;
    private final HashMap<String, Object> recordMap;
    
    // constructor, getters

问题

entry 过期时，由于 CacheKey 的 class not found 异常而引发序列化异常。

Method threw 'com.hazelcast.nio.serialization.HazelcastSerializationException' exception. Cannot evaluate com.hazelcast.map.impl.DataAwareEntryEvent.toString()

2021-10-19 16:41:13,921 ERROR [hz.client_1.event-4] c.h.c.impl.spi.ClientListenerService hz.client_1 [nifi] [4.2] hz.client_1.event-4 caught an exception while processing:com.hazelcast.client.impl.spi.impl.listener.ClientListenerServiceImpl$ClientEventProcessor@782e8844
com.hazelcast.nio.serialization.HazelcastSerializationException: java.lang.ClassNotFoundException: com.myapp.expirytest.CacheKey
        at com.hazelcast.internal.serialization.impl.defaultserializers.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:90)
        at com.hazelcast.internal.serialization.impl.defaultserializers.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:79)
        at com.hazelcast.internal.serialization.impl.StreamSerializerAdapter.read(StreamSerializerAdapter.java:44)
        at com.hazelcast.internal.serialization.impl.AbstractSerializationService.toObject(AbstractSerializationService.java:208)
        at com.hazelcast.map.impl.DataAwareEntryEvent.getKey(DataAwareEntryEvent.java:74)
        at com.ipfli.drs.nifi.processor.hzexpirytest.ExpiryTest.lambda$onScheduled$0(ExpiryTest.java:112)
        at com.hazelcast.map.impl.MapListenerAdaptors.lambda$null$6(MapListenerAdaptors.java:93)
        at com.hazelcast.map.impl.InternalMapListenerAdapter.onEvent(InternalMapListenerAdapter.java:56)
        at com.hazelcast.map.impl.InternalMapListenerAdapter.onEvent(InternalMapListenerAdapter.java:35)
        at com.hazelcast.client.impl.proxy.ClientMapProxy$AbstractClientMapEventHandler.handleEntryEvent(ClientMapProxy.java:2004)
        at com.hazelcast.client.impl.proxy.ClientMapProxy$ClientMapEventHandler$1.handleEntryEvent(ClientMapProxy.java:1981)
        at com.hazelcast.client.impl.protocol.codec.MapAddEntryListenerCodec$AbstractEventHandler.handle(MapAddEntryListenerCodec.java:164)
        at com.hazelcast.client.impl.proxy.ClientMapProxy$ClientMapEventHandler.handle(ClientMapProxy.java:1989)
        at com.hazelcast.client.impl.proxy.ClientMapProxy$ClientMapEventHandler.handle(ClientMapProxy.java:1971)
        at com.hazelcast.client.impl.spi.impl.listener.ClientListenerServiceImpl.handleEventMessageOnCallingThread(ClientListenerServiceImpl.java:189)
        at com.hazelcast.client.impl.spi.impl.listener.ClientListenerServiceImpl$ClientEventProcessor.run(ClientListenerServiceImpl.java:356)
        at com.hazelcast.internal.util.executor.StripedExecutor$Worker.process(StripedExecutor.java:245)
        at com.hazelcast.internal.util.executor.StripedExecutor$Worker.run(StripedExecutor.java:228)
Caused by: java.lang.ClassNotFoundException: com.myapp.expirytest.CacheKey
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        at com.hazelcast.internal.nio.ClassLoaderUtil.tryLoadClass(ClassLoaderUtil.java:289)
        at com.hazelcast.internal.nio.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:249)
        at com.hazelcast.internal.nio.IOUtil$ClassLoaderAwareObjectInputStream.resolveClass(IOUtil.java:910)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1984)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1848)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2158)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1665)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:501)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:459)
        at com.hazelcast.internal.serialization.impl.defaultserializers.JavaDefaultSerializers$JavaSerializer.read(JavaDefaultSerializers.java:86)
        ... 17 common frames omitted

测试 jar 部署到 user-lib 文件夹。 我知道 CacheKey 类已正确部署在服务器端，因为我使用不同的服务来获取它，它可以正常工作。 做了很多其他的测试。唯一的问题是 EntryExpiredListener。

Hazelcast 服务器和 JVM 客户端都在我的本地机器上运行，单节点。 Hazelcast 4.2.1 版

所以一切都在同一个 jar 中，我知道类部署在服务器端。 我错过了什么？

Answer 1

通过为 HazelcastClient 设置类加载器解决了这个问题：

ClientConfig clientConfig = new ClientConfig();
clientConfig.setClassLoader(TestService.class.getClassLoader());

我调试了 Hazelcast 代码并注意到它正在尝试使用 NarClassLoader 来加载类。 NarClassLoader 来自我正在使用的 Apache Nifi 框架。 Nifi 将代码打包成 .nar 文件而不是 .jar 文件。

不知道为什么它会尝试将此类加载器仅用于 EntryExpiredListener。其他服务正在工作，这意味着它正在使用不同的类加载器并成功加载类。