NoClassDefFoundError: jdk/net/ExtendedSocketOptions crashes application startup instead of falling back to plain SO_KEEPALIVE

[eikelang-vm]

Bug Report

Current Behavior

When starting a SpringBoot 4.1.0 application that has Redis autoconfigured, it crashes on startup with an exception originating from lettuce:

Stack trace

``[org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory]: Factory method 'redisConnectionFactory' threw exception with message: jdk/net/ExtendedSocketOptions at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:201) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:977) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:621) at org.springframework.boot.web.server.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:756) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:445) at org.springframework.boot.SpringApplication.run(SpringApplication.java:321) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1365) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1354) at com.vw.mbbc.cdpsync.Application.main(Application.java:23) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at org.springframework.boot.loader.launch.Launcher.launch(Launcher.java:106) at org.springframework.boot.loader.launch.Launcher.launch(Launcher.java:64) at org.springframework.boot.loader.launch.JarLauncher.main(JarLauncher.java:40) Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cacheManager' defined in class path resource [org/springframework/boot/cache/autoconfigure/RedisCacheConfiguration.class]: Unsatisfied dependency expressed through method 'cacheManager' parameter 4: Error creating bean with name 'redisConnectionFactory' defined in class path resource [org/springframework/boot/data/redis/autoconfigure/LettuceConnectionConfiguration.class]: Failed to instantiate [org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory]: Factory method 'redisConnectionFactory' threw exception with message: jdk/net/ExtendedSocketOptions at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:804) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:546) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1360) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1192) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:565) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:525) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:333) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:371) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:331) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:309) ... 15 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'redisConnectionFactory' defined in class path resource [org/springframework/boot/data/redis/autoconfigure/LettuceConnectionConfiguration.class]: Failed to instantiate [org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory]: Factory method 'redisConnectionFactory' threw exception with message: jdk/net/ExtendedSocketOptions at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:657) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:645) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1360) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1192) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:565) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:525) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:333) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:371) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:331) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:201) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveBean(DefaultListableBeanFactory.java:1232) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1711) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1658) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:912) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791) ... 25 more Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory]: Factory method 'redisConnectionFactory' threw exception with message: jdk/net/ExtendedSocketOptions at org.springframework.beans.factory.support.SimpleInstantiationStrategy.lambda$instantiate$0(SimpleInstantiationStrategy.java:183) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiateWithFactoryMethod(SimpleInstantiationStrategy.java:72) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:152) at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ... 39 more Caused by: java.lang.NoClassDefFoundError: jdk/net/ExtendedSocketOptions at io.lettuce.core.resource.ExtendedKeepAliveSupport$ExtendedNioSocketOptions.(ExtendedKeepAliveSupport.java:110) at io.lettuce.core.resource.ExtendedKeepAliveSupport.(ExtendedKeepAliveSupport.java:45) at io.lettuce.core.SocketOptions$Builder.(SocketOptions.java:118) at io.lettuce.core.SocketOptions$Builder.(SocketOptions.java:107) at io.lettuce.core.SocketOptions.builder(SocketOptions.java:92) at io.lettuce.core.SocketOptions.create(SocketOptions.java:101) at io.lettuce.core.ClientOptions.(ClientOptions.java:79) at org.springframework.data.redis.connection.lettuce.LettuceClientConfiguration$LettuceClientConfigurationBuilder.(LettuceClientConfiguration.java:182) at org.springframework.data.redis.connection.lettuce.LettuceClientConfiguration.builder(LettuceClientConfiguration.java:138) at org.springframework.boot.data.redis.autoconfigure.LettuceConnectionConfiguration.createBuilder(LettuceConnectionConfiguration.java:166) at org.springframework.boot.data.redis.autoconfigure.LettuceConnectionConfiguration.getLettuceClientConfiguration(LettuceConnectionConfiguration.java:149) at org.springframework.boot.data.redis.autoconfigure.LettuceConnectionConfiguration.createConnectionFactory(LettuceConnectionConfiguration.java:122) at org.springframework.boot.data.redis.autoconfigure.LettuceConnectionConfiguration.redisConnectionFactory(LettuceConnectionConfiguration.java:99) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.lambda$instantiate$0(SimpleInstantiationStrategy.java:155) ... 42 more Caused by: java.lang.ClassNotFoundException: jdk.net.ExtendedSocketOptions at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:445) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:593) at org.springframework.boot.loader.net.protocol.jar.JarUrlClassLoader.loadClass(JarUrlClassLoader.java:107) at org.springframework.boot.loader.launch.LaunchedClassLoader.loadClass(LaunchedClassLoader.java:91) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ... 58 more" ``

Input Code

No specific code, attempting to start a SpringBoot application with redis configured in will lead to this error under the conditions specified in "Environment".

Expected behavior/code

Fall back to plain SO_KEEPALIVE (was made default in 7.5.0) and continue running with reduced keepalive granularity. I.e. graceful degradation rather than full application crash. In other words: pre-7.5.0 behaviour.

Environment

• lettuce-core: 7.5.2.RELEASE (via spring-boot-starter-data-redis, Spring Boot 4.1.0)
• Previously working: lettuce-core 6.8.2.RELEASE (via Spring Boot 4.0.6), no crash
• JDK: 21, running as a custom jlink-built runtime image that does not include the jdk.net module, inside a docker container. Unfortunately we don't control the process the creation of that image, otherwise adding jdk.net to the list of modules would've been the path of least resistance.

Possible Solution

Making keepalive behaviour configurable would do in a pinch, defensively guarding against non-availability of jdk.netExtendedSocketOptions would probably be the more sustainable (and elegant) solution. For the purposes of what I'm trying to achieve (being able to closely keep tracking springboot releases), either is fine.

Regression note

This did not occur with lettuce-core 6.8.2.RELEASE (Spring Boot 4.0.6), where extended keepalive was opt-in. It became a startup-blocking issue specifically because #3669 made the capability probe run unconditionally as part of a static default.

[a-TODO-rov]

Hey @eikelang-vm
Thanks for your report. Indeed - the problem is that we are relying that jdk.net.ExtendedSocketOptions is on the classpath, which is obviously not your case.
The PR you are mentioning made the ExtendedKeepalive enabled by default and this is why you are hitting this problem now, but even before if you decided to enable it by yourself you would get the same problem.
We currently want to support this option enabled by default, so the fix would be to check if jdk.net.ExtendedSocketOptions is on the classpath.

[meteaksoyy]

Hi @a-TODO-rov, I'd like to pick this up. Based on your comment, my plan: guard the jdk.net.ExtendedSocketOptions usage in ExtendedKeepAliveSupport with a classpath availability check, so that when the module is absent (e.g. jlink images without jdk.net) Lettuce logs a note and falls back to plain SO_KEEPALIVE instead of throwing NoClassDefFoundError from the static initializer. I'll add a test and open a PR shortly.