多Ignite客户端创建集群单例服务，远程服务器序列化发现数据失败

Hey there, let's break down your Ignite issue step by step. First, let's clarify your understanding about cluster singleton services—you're partially right, but there's a key detail you might be missing that's leading to this error.

When you call the method to create a cluster singleton service from a second client, Ignite does check if the service already exists in the cluster. However, the client still sends the service's metadata (like class definitions, configuration) to the cluster for validation during the discovery process. The Failed to marshal discovery data error isn't about Ignite trying to re-create the service—it's a serialization failure happening while transmitting that metadata between nodes.

Here are the most likely reasons for this error and how to fix them:

• Missing Serializable Interface: Ensure your cluster singleton service class, and any objects it references in its configuration, implement the java.io.Serializable interface. Ignite needs to serialize this data to pass it between nodes during discovery. If even one dependent class isn't serializable, you'll hit this marshaling error.
• Classpath Mismatch: All Ignite servers and clients must have the exact same version of your service class (and its dependencies) in their classpaths. If one server has a different version or missing class, it can't deserialize the discovery data sent by the client.
• Custom Serializer Issues: If you're using a custom serializer like Kryo (instead of the default JDK serializer), make sure your service class is explicitly registered with the serializer. Ignite won't automatically know how to serialize custom classes with non-default serializers.
• Optimize Client Logic (Optional but Helpful): While Ignite should handle duplicate service creation requests gracefully, you can add a check before calling the create method to avoid unnecessary metadata transmission. Use:

  if (ignite.services().serviceDescriptor("your-service-name") == null) {
      // Create and deploy the cluster singleton service
  }
  

• Check Full Error Stack: The Failed to marshal discovery data error usually has a nested exception (like NotSerializableException) that points to the exact class causing the problem. Look at the full server log to pinpoint the issue quickly.

The error isn't because Ignite is trying to re-create the singleton service—it's a serialization failure during the discovery data exchange. Fixing the serialization issue (either via Serializable implementation, classpath alignment, or serializer configuration) will resolve the problem.

内容的提问来源于stack exchange，提问作者dvlcis