What is the cause of this null pointer in the framework code? I recently started migrating some of our application stack from ehcache with JGroups to Redis. As part of this, we are maintaining the use of ehcache as a second level cache for some functionality. I am getting consistent NullPointerExceptions in the connection code of the client libraries (Jedis or Lettuce) during some of the integration tests (~900 of them). However, the caching mechanism does work during normal application running, and the caching works properly during some of the integration tests. The existing application code makes use of @Cacheable which works well for me. I did the integration by using the following gradle dependencies and cache configuration:
compile 'org.springframework.data:spring-data-redis:1.6.0.RELEASE'
compile 'biz.paluch.redis:lettuce:'3.3.Final'
redisContext.xml
<bean id="lettucePool" class="org.springframework.data.redis.connection.lettuce.DefaultLettucePool">
<property name="hostName" value="${redis.host}" />
<property name="port" value="${redis.port}" />
<property name="poolConfig" ref="lettucePoolConfiguration" />
</bean>
<bean id="lettucePoolConfiguration" class="org.springframework.data.redis.connection.PoolConfig">
<property name="maxIdle" value="900"/>
<property name="maxActive" value="1000" />
<property name="maxTotal" value="1200" />
<property name="testOnBorrow" value="true" />
<property name="testOnReturn" value="true" />
</bean>
<bean id="lettuceConnectionFactory" class="org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory" p:host-name="${redis.host}" p:port="${redis.port}">
<constructor-arg index="0" ref="lettucePool"/>
<property name="validateConnection" value="true"></property>
<property name="shareNativeConnection" value="true"></property>
</bean>
<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate" p:connection-factory-ref="lettuceConnectionFactory">
<property name="keySerializer">
<bean class="c.h.c.c.util.MultiKeySerializer"/> <!-- Used to translate SPeL array to key String -->
</property>
<property name="hashKeySerializer">
<bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/>
</property>
</bean>
<bean id="redisCacheManager" class="org.springframework.data.redis.cache.RedisCacheManager">
<constructor-arg index="0" ref="redisTemplate"></constructor-arg>
<property name="cacheNames">
<set>
<value>cachenames......</value>
</set>
</property>
<property name="expires">
<map>
<entry key="cachenames......" value="times...."/>
</map>
</property>
</bean>
cacheContext.xml
<cache:annotation-driven cache-manager="ehcacheManager"/>
<cache:annotation-driven cache-manager="redisCacheManager"/>
<bean id="ehcacheManager" class="org.springframework.cache.ehcache.EhCacheCacheManager">
<property name="cacheManager" ref="ehcache" />
</bean>
<bean id="ehcache" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
<property name="configLocation" value="classpath:ehcache.xml" />
<property name="acceptExisting" value="true" />
</bean>
<bean id="userCacheInstance" factory-bean="ehcacheManager" factory-method="getCache">
<constructor-arg value="user" />
</bean>
<import resource="classpath:redisContext.xml />
Exception:
org.springframework.data.redis.RedisSystemException: Unknown redis exception; nested exception is java.lang.NullPointerException
at org.springframework.data.redis.FallbackExceptionTranslationStrategy.getFallback(FallbackExceptionTranslationStrategy.java:48)
at org.springframework.data.redis.FallbackExceptionTranslationStrategy.translate(FallbackExceptionTranslationStrategy.java:38)
at org.springframework.data.redis.connection.lettuce.LettuceConnection.convertLettuceAccessException(LettuceConnection.java:305)
at org.springframework.data.redis.connection.lettuce.LettuceConnection.get(LettuceConnection.java:1175)
at sun.reflect.GeneratedMethodAccessor353.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.data.redis.core.CloseSuppressingInvocationHandler.invoke(CloseSuppressingInvocationHandler.java:57)
at com.sun.proxy.$Proxy137.get(Unknown Source)
at org.springframework.data.redis.cache.RedisCache$1.doInRedis(RedisCache.java:110)
at org.springframework.data.redis.cache.RedisCache$1.doInRedis(RedisCache.java:106)
at org.springframework.data.redis.cache.RedisCache$AbstractRedisCacheCallback.doInRedis(RedisCache.java:424)
at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:191)
at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:153)
at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:141)
at org.springframework.data.redis.cache.RedisCache.get(RedisCache.java:105)
at org.springframework.data.redis.cache.RedisCache.get(RedisCache.java:90)
at org.springframework.cache.interceptor.AbstractCacheInvoker.doGet(AbstractCacheInvoker.java:68)
at org.springframework.cache.interceptor.CacheAspectSupport.findInCaches(CacheAspectSupport.java:466)
at org.springframework.cache.interceptor.CacheAspectSupport.findCachedItem(CacheAspectSupport.java:432)
at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:336)
at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:302)
at org.springframework.cache.interceptor.CacheInterceptor.invoke(CacheInterceptor.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
at com.sun.proxy.$Proxy93.getMasterAttributeValues(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.cache.interceptor.CacheInterceptor$1.invoke(CacheInterceptor.java:52)
at org.springframework.cache.interceptor.CacheAspectSupport.invokeOperation(CacheAspectSupport.java:320)
at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:353)
at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:302)
at org.springframework.cache.interceptor.CacheInterceptor.invoke(CacheInterceptor.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
at com.sun.proxy.$Proxy95.search(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
at com.sun.proxy.$Proxy96.search(Unknown Source)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:155)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:254)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:193)
at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecuter.runTestClass(JUnitTestClassExecuter.java:114)
at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecuter.execute(JUnitTestClassExecuter.java:57)
at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassProcessor.processTestClass(JUnitTestClassProcessor.java:66)
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:32)
at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:93)
at com.sun.proxy.$Proxy3.processTestClass(Unknown Source)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.processTestClass(TestWorker.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:147)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:129)
at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:404)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:46)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at com.lambdaworks.redis.protocol.CommandArgs.write(CommandArgs.java:121)
at com.lambdaworks.redis.protocol.CommandArgs.addKey(CommandArgs.java:54)
at com.lambdaworks.redis.BaseRedisCommandBuilder.createCommand(BaseRedisCommandBuilder.java:26)
at com.lambdaworks.redis.RedisCommandBuilder.get(RedisCommandBuilder.java:357)
at com.lambdaworks.redis.RedisAsyncConnectionImpl.get(RedisAsyncConnectionImpl.java:354)
at sun.reflect.GeneratedMethodAccessor354.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.lambdaworks.redis.FutureSyncInvocationHandler.handleInvocation(FutureSyncInvocationHandler.java:63)
at com.google.common.reflect.AbstractInvocationHandler.invoke(AbstractInvocationHandler.java:87)
at com.sun.proxy.$Proxy136.get(Unknown Source)
at org.springframework.data.redis.connection.lettuce.LettuceConnection.get(LettuceConnection.java:1173)
... 139 more
Ok, there were many problems here. None of them with Spring-Data-Redis or the connection client libraries. The first one belongs to how we are generating our keys. If you use:
@Cacheable(....., key={#key1,#key2})
Then Spring will treat the generated key as an ArrayList. I could not get the default org.springframework.data.redis.serializer.StringRedisSerializer to work with that as it will run into a ClassCastException due to ArrayList != String. As a result of that, I created the MultiKeySerializer to loop through the ArrayList when it gets an instance of one to generate the key from.
public class MultiKeySerializer implements RedisSerializer<Object>{
private final Charset charset;
public MultiKeySerializer() {
this(Charset.forName("UTF8"));
}
public MultiKeySerializer(Charset charset) {
Assert.notNull(charset);
this.charset = charset;
}
@Override
public byte[] serialize(Object t) throws SerializationException {
if(t instanceof ArrayList){
StringBuilder sb = new StringBuilder();
ArrayList tList = (ArrayList) t;
for(Object o: tList){
sb.append(o == null ? null: o.toString());
}
String string = sb.toString();
return (string == null ? null : string.getBytes(charset));
}
// return null - used to return null. Root cause.
return t == null ? null : t.toString().getBytes(charset);
}
@Override
public String deserialize(byte[] bytes) throws SerializationException {
return (bytes == null ? null : new String(bytes, charset));
}
}
The issue was that some of the code used @Cacheable and didn't specify the key attribute. This caused Spring to treat it as a SimpleKey and thus fall through the key gen logic. While Spring-Data-Redis was not the culprit, it would be nice if they gave a more descriptive exception when the key is null.