Class loading fails on an interrupted thread causing com.mongodb.event.ServerClosedEvent to fail to load when Mongo detects a cluster change

[manjian14]

We've encountered a connectivity problem after migrating from Spring Boot 3.1.5/3.1.6 to 3.2.0. The error log points to a missing class:

java.lang.ClassNotFoundException: com.mongodb.event.ServerClosedEvent

This is affecting our connection to MongoDB "AWS DocumentDB." Any guidance or resolution on this matter would be greatly appreciated.

[mhalbritter]

Hello!

I can't see any code from Boot in the stacktrace, besides the JAR loader. I'm not sure if this has something to do with the Uber JAR rewrite. Can you please try with the classic loader implementation and report back if that fixes the issue?

See here for details: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-3.2-Release-Notes#nested-jar-support

[manjian14]

The connectivity issue with MongoDB "AWS DocumentDB" appears resolved after implementing the classic loader in Spring Boot 3.2.0:

bootJar {
    archiveFileName = "${rootProject.name}.${archiveExtension.get()}"
    loaderImplementation = LoaderImplementation.CLASSIC
}

Any additional insights or recommendations moving forward would be appreciated.

[mhalbritter]

cc @philwebb

[wilkinsona]

@manjian14 The stack trace would suggest that the problem occurs when there's a change in the topology of the cluster but I haven't been able to reproduce it. Can you please provide a minimal sample and the steps to follow to cause the failure?

[manjian14]

I've configured my application to connect to an AWS DocDB cluster using the standard driver configuration. Below is a snippet from my MongoDbConfiguration class:

@Slf4j
@Configuration
@EnableMongoRepositories(value = "com.????")
@ConditionalOnProperty(prefix = "mongo.connection", value = "string")
public class MongoDbConfiguration extends AbstractMongoClientConfiguration {

    @Value("${mongo.connection.string}")
    private String connectionString;

    @Override
    @Primary
    @Bean
    public @NonNull MongoClient mongoClient() {
        return MongoClients.create(connectionString);
    }

    @Override
    protected @NonNull String getDatabaseName() {
        return "???";
    }
}

In this setup, I've embedded the username and password within the cluster URL. The cluster has two replica sets, one for reading and one for writing. Additionally, the database is not accessible from outside; access is restricted either by whitelisted IP addresses or by project roles within the ECS cluster.

The AWS DocDB version is 5.0.0, the latest version as per AWS recommendations. The project is using Gradle version 8.5 and Java version 17. The base image is amazoncorretto:17-al2023-headful, and during the image build process, I've imported the SSL certificate using the keytool tool.

If you have any specific questions or if there's anything else you'd like to know, feel free to ask!

[philwebb]

@manjian14 Is there any chance you could switch back to the DEFAULT loader implementation and try 3.2.1-SNAPSHOT? We've fixed a few bugs with the nested loader. I'm doubtful that we've caught this one, but I'd like to check since it seems hard for us to replicate the problem locally.