Eager initialization of `LettuceConnectionFactory` configured for Redis Cluster causes `ClassCastException`

[sangeethaPrem]

Hi,

 

When I try to call the initConnection() on my clustered redis, i get the error java.lang.ClassCastException: io.lettuce.core.cluster.StatefulRedisClusterConnectionImpl cannot be cast to io.lettuce.core.api.StatefulRedisConnection

                at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory.getSharedConnection(LettuceConnectionFactory.java:975)

 

looking at the code it seems like the class cast is only for the StatefulRedisConnection, where as the validateConnection() supports both StatefulRedisConnection and StatefulRedisClusterConnection.

 

any one faced this before? on how to achieve this?
We are doing lazy initialisation to the redis cluster.
Please help.
 

Thanks.

[mp911de]

If you would like us to spend some time helping you to diagnose the problem, please spend some time describing it and, ideally, providing a minimal sample that reproduces the problem.

[aronica]

@mp911de
I encounter this issue here, you only need to enable eagerInitialization while configure Bean LettuceConnectionFactory with Redis cluster mode,
I made a sample project here. https://github.com/aronica/demo.
The stacktrace of my application is like below,

        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1804) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.12.jar!/:5.3.12]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.12.jar!/:5.3.12]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.5.6.jar!/:2.5.6]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) [spring-boot-2.5.6.jar!/:2.5.6]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:434) [spring-boot-2.5.6.jar!/:2.5.6]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:338) [spring-boot-2.5.6.jar!/:2.5.6]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1343) [spring-boot-2.5.6.jar!/:2.5.6]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1332) [spring-boot-2.5.6.jar!/:2.5.6]
        at com.example.demo.DemoApplication.main(DemoApplication.java:10) [classes!/:0.0.1-SNAPSHOT]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_292]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_292]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_292]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_292]
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49) [demo-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:108) [demo-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:58) [demo-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:88) [demo-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
Caused by: java.lang.ClassCastException: io.lettuce.core.cluster.StatefulRedisClusterConnectionImpl cannot be cast to io.lettuce.core.api.StatefulRedisConnection
        at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory.getSharedConnection(LettuceConnectionFactory.java:1089) ~[spring-data-redis-2.5.6.jar!/:2.5.6]
        at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory.initConnection(LettuceConnectionFactory.java:543) ~[spring-data-redis-2.5.6.jar!/:2.5.6]
        at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory.afterPropertiesSet(LettuceConnectionFactory.java:355) ~[spring-data-redis-2.5.6.jar!/:2.5.6]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) ~[spring-beans-5.3.12.jar!/:5.3.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.12.jar!/:5.3.12]
        ... 24 common frames omitted

The line throws exception is as below:

         @Nullable
	protected StatefulRedisConnection<byte[], byte[]> getSharedConnection() {
		return shareNativeConnection ? (StatefulRedisConnection) getOrCreateSharedConnection().getConnection() : null;
	}

when we are in cluster mode, getOrCreateSharedConnection().getConnection() will return io.lettuce.core.cluster.StatefulRedisClusterConnectionImpl instead of instance of io.lettuce.core.api.StatefulRedisConnection

[mp911de]

That is expected. When configuring to run with Redis Cluster, you will receive a StatefulRedisClusterConnection object (instead of StatefulRedisConnection) because Redis Cluster works differently from standalone Redis.

[aronica]

That is expected. When configuring to run with Redis Cluster, you will receive a StatefulRedisClusterConnection object (instead of StatefulRedisConnection) because Redis Cluster works differently from standalone Redis.

So we could not use eagerInitialization with redis cluster mode? but we don't have a cluster mode LettuceConnectionFactory

[aronica]

That is expected. When configuring to run with Redis Cluster, you will receive a StatefulRedisClusterConnection object (instead of StatefulRedisConnection) because Redis Cluster works differently from standalone Redis.

@mp911de please take a review again, I do not quite understand the reason on it, the workflow is when I enabled eagerInitialization in LettuceConnectionFactory, the call stack is (all code is in LettuceConnectionFactory.java)

afterPropertiesSet()->initConnection()->getSharedConnection()->getOrCreateSharedConnection().getConnection() 

as you said, getSharedConnection() always tried to cast StatefulRedisClusterConnection to StatefulRedisConnection when we are in redis cluster mode, if you think that's expected, then we should clarify it that eagerInitialization only works with none redis cluster mode in javadoc.

[mp911de]

Thanks for elaborating more. Initially, the ticket description was confusing so the fact that Spring Data Redis has a bug went unnoticed. I can confirm that there's a bug and we need to fix it.