@Retryable with recover method specified broken with NullPointerException

[rohithaksha]

I am trying @retryable with @recover example in a springboot application. When I specify the recover method name in the @retryable parameter, it is failing with NullPointerException (listed below). I have listed the log and sample code with dependencies below.

Here's the exception:

2023-09-10 10:46:20.984 ERROR 22040 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException: Cannot invoke "java.lang.Class.isAssignableFrom(java.lang.Class)" because "meta.type" is null] with root cause

java.lang.NullPointerException: Cannot invoke "java.lang.Class.isAssignableFrom(java.lang.Class)" because "meta.type" is null
	at org.springframework.retry.annotation.RecoverAnnotationRecoveryHandler.findClosestMatch(RecoverAnnotationRecoveryHandler.java:146) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.annotation.RecoverAnnotationRecoveryHandler.recover(RecoverAnnotationRecoveryHandler.java:75) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.interceptor.RetryOperationsInterceptor$ItemRecovererCallback.recover(RetryOperationsInterceptor.java:159) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.support.RetryTemplate.handleRetryExhausted(RetryTemplate.java:543) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:389) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:225) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.interceptor.RetryOperationsInterceptor.invoke(RetryOperationsInterceptor.java:124) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.retry.annotation.AnnotationAwareRetryOperationsInterceptor.invoke(AnnotationAwareRetryOperationsInterceptor.java:160) ~[spring-retry-2.0.2.jar:na]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.29.jar:5.3.29]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.29.jar:5.3.29]
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) ~[spring-aop-5.3.29.jar:5.3.29]
	at com.consumer.retry.service.RetryConsumerService1$$EnhancerBySpringCGLIB$$b63b66c5.getExample1FromProducer(<generated>) ~[classes/:na]
	at com.consumer.retry.controller.RetryConsumerController.getExample1(RetryConsumerController.java:22) ~[classes/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.29.jar:5.3.29]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1072) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:965) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:529) ~[tomcat-embed-core-9.0.79.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.29.jar:5.3.29]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623) ~[tomcat-embed-core-9.0.79.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.29.jar:5.3.29]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.29.jar:5.3.29]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.29.jar:5.3.29]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.29.jar:5.3.29]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.29.jar:5.3.29]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.29.jar:5.3.29]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:390) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:926) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1790) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.79.jar:9.0.79]
	at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]

See the code below.

@SpringBootApplication
@EnableRetry
public class RetryConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(RetryConsumerApplication.class, args);
    }

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder restTemplateBuilder) {
        return restTemplateBuilder
                .setConnectTimeout(Duration.ofMillis(5000))
                .setReadTimeout(Duration.ofMillis(2000))
                .build();
    }

}

@Slf4j
@RestController
public class RetryConsumerController {

    @Autowired
    private RetryConsumerService1 retryConsumerService1;

    @GetMapping(path = "/producer/example1")
    public ResponseEntity<Value1> getExample1() throws RetryConsumerException {
        return ResponseEntity.ok(retryConsumerService1.getExample1FromProducer(new Param1("param 1")));
    }
}

public class RetryConsumerException extends Throwable {
    public RetryConsumerException(String s, Exception e) {
        super(s, e);
    }
}

@Slf4j
@Service
public class RetryConsumerService1 {
    private RestTemplate restTemplate;

    public RetryConsumerService1(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }

    @Retryable(recover = "recover1", retryFor = RetryConsumerException.class, maxAttemptsExpression = "${retry.maxAttempts:2}", backoff = @Backoff(delay = 1000))
    public Value1 getExample1FromProducer(Param1 param1) throws RetryConsumerException {

        String url = "http://localhost:8081/example1";

        try {
            Value1 response = new Value1(restTemplate.exchange(url, HttpMethod.GET, null, String.class).getBody());

            return response;
        } catch (Exception e) {
            throw new RetryConsumerException("1: Caught Exception while calling url: " + url, e);
        }
    }

    @Recover
//    public Value1 recover1(Param1 param1) { // DOESN'T WORK
//    public Value1 recover1(Param1 param1, RetryConsumerException e) { // DOESN'T WORK
    public Value1 recover1(Param1 param1, Throwable t) {
        String response = "ERROR 1: Sorry! Error while getting the requested info. Please try again later!";
        log.error(response);

        return new Value1(response);
    }
}

Here're the dependencies:

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.15</version>
    </parent>

        <dependency>
            <groupId>org.springframework.retry</groupId>
            <artifactId>spring-retry</artifactId>
            <version>2.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>6.0.11</version>
        </dependency>

[artembilan]

According to the @Recover Javadocs your method signature is wrong:

 * Annotation for a method invocation that is a recovery handler. A suitable recovery
 * handler has a first parameter of type Throwable (or a subtype of Throwable) and a
 * return value of the same type as the <code>@Retryable</code> method to recover from.
 * The Throwable first argument is optional (but a method without it will only be called
 * if no others match). Subsequent arguments are populated from the argument list of the
 * failed method in order.

So, it has to be like this:

 public Value1 recover1(RetryConsumerException e, Param1 param1)

Saying that it doesn't mean that this NPE must not be fixed.
Will look into that for upcoming release this week.

Thank you for the report!

[artembilan]

Has been fixed with this: #371.

Will be released in next version this week.

[rohithaksha]

Thank you for the follow-up. I tried that option too, recover method still doesn't get called.
public Value1 recover1(RetryConsumerException ex, Param1 param1) {

Only way it works is by removing recover parameter from @retryable and below listed recover method without Exception in the parameter.
public Value1 recover1(Param1 param1) {

Retryable without recover parameter.
@Retryable(retryFor = RetryConsumerException.class, maxAttemptsExpression = "${retry.maxAttempts:2}", backoff = @Backoff(delay = 1000))