Spring Boot ClassCastException on composite micro service, after some time - OK - spring

Question

I have strange behavior of my composite microservice (API gateway) of 2 microservices. On first HTTP request it returns the ClassCastException, but after some time it returns normal JSON. How can I set the application to return normal JSON right on the first HTTP request?
Configuration for all 3 services is similar: spring.application.name, server port, Eureka registration address.
There are 2 microservices: car-service (annotated with #Controller) and truck-service (annotated with #RestController), the methods which return List<Car> and List<Truck> are correspondingly:
#HystrixCommand(commandKey = "getCars", groupKey = "Cars")
#RequestMapping(value = "/cars", method = RequestMethod.GET)
public List<Car> getCars() {
return carService.getAllCars();
}
and
#ResponseBody
#RequestMapping(value = "/trucks", method = RequestMethod.GET)
public List<Truck> getTrucks() {
return truckService.getAllTrucks();
}
(setting both services to #Controller or #RestController doesn't affect the behavior)
Composite Vehicle service has 2 interfaces injected with #FeignClient annotation and returns composite object VehicleSummary which has List<Car> and List<Truck> fields with standard getters and setters:
#Component
public class VehicleService {
#Inject
private CarClient carClient;
#Inject
private TruckClient truckClient;
public VehicleSummary getAllVehicles() {
List<Car> cars = carClient.getAllCars();
List<Truck> trucks = truckClient.getTrucks();
VehicleSummary summary = new VehicleSummary();
summary.setCars(cars);
summary.setTrucks(trucks);
return summary;
}
}
The full source code is available at https://github.com/t3rmin41/simple-microservices-app
The stacktrace of the exception is below :
2015-12-21 21:17:00.560 INFO 26207 --- [nio-8883-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring FrameworkServlet 'dispatcherServlet'
2015-12-21 21:17:00.560 INFO 26207 --- [nio-8883-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started
2015-12-21 21:17:00.612 INFO 26207 --- [nio-8883-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 52 ms
2015-12-21 21:17:00.967 INFO 26207 --- [trix-Vehicles-1] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext#31eb7d: startup date [Mon Dec 21 21:17:00 EET 2015]; parent: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext#2db9fb
2015-12-21 21:17:01.020 INFO 26207 --- [trix-Vehicles-1] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2015-12-21 21:17:01.383 INFO 26207 --- [trix-Vehicles-1] c.netflix.config.ChainedDynamicProperty : Flipping property: car-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2015-12-21 21:17:01.525 INFO 26207 --- [trix-Vehicles-1] c.netflix.loadbalancer.BaseLoadBalancer : Client:car-service instantiated a LoadBalancer:DynamicServerListLoadBalancer:{NFLoadBalancer:name=car-service,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2015-12-21 21:17:01.593 INFO 26207 --- [trix-Vehicles-1] c.netflix.config.ChainedDynamicProperty : Flipping property: car-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2015-12-21 21:17:01.600 INFO 26207 --- [trix-Vehicles-1] c.n.l.DynamicServerListLoadBalancer : DynamicServerListLoadBalancer for client car-service initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=car-service,current list of Servers=[nikzgs-Latitude-E5420:8881],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone; Instance count:1; Active connections count: 0; Circuit breaker tripped count: 0; Active connections per server: 0.0;]
},Server stats: [[Server:nikzgs-Latitude-E5420:8881; Zone:defaultZone; Total Requests:0; Successive connection failure:0; Total blackout seconds:0; Last connection made:Thu Jan 01 03:00:00 EET 1970; First connection made: Thu Jan 01 03:00:00 EET 1970; Active Connections:0; total failure count in last (1000) msecs:0; average resp time:0.0; 90 percentile resp time:0.0; 95 percentile resp time:0.0; min resp time:0.0; max resp time:0.0;stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList#a14ec6
2015-12-21 21:17:02.054 ERROR 26207 --- [nio-8883-exec-1] 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.ClassCastException: java.lang.String cannot be cast to my.vehicle.entity.VehicleSummary] with root cause
java.lang.ClassCastException: java.lang.String cannot be cast to my.vehicle.entity.VehicleSummary
at my.simple.vehicle.VehicleController$$EnhancerBySpringCGLIB$$3b97a077.getAllVehicles(<generated>) ~[composite-vehicle-service-0.0.1-SNAPSHOT.jar!/:0.0.1-SNAPSHOT]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_65]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_65]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_65]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_65]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:242) ~[spring-boot-actuator-1.3.0.RELEASE.jar!/:1.3.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:111) ~[spring-boot-actuator-1.3.0.RELEASE.jar!/:1.3.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.3.0.RELEASE.jar!/:1.3.0.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar!/:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217) ~[tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_65]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_65]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.28.jar!/:8.0.28]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_65]
2015-12-21 21:17:02.535 INFO 26207 --- [ool-10-thread-1] c.netflix.config.ChainedDynamicProperty : Flipping property: car-service.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2015-12-21 21:17:07.778 INFO 26207 --- [pool-6-thread-1] com.netflix.discovery.DiscoveryClient : DiscoveryClient_VEHICLE-SERVICE/nikzgs-Latitude-E5420 - Re-registering apps/VEHICLE-SERVICE
2015-12-21 21:17:07.778 INFO 26207 --- [pool-6-thread-1] com.netflix.discovery.DiscoveryClient : DiscoveryClient_VEHICLE-SERVICE/nikzgs-Latitude-E5420: registering service...
2015-12-21 21:17:07.791 INFO 26207 --- [pool-6-thread-1] com.netflix.discovery.DiscoveryClient : DiscoveryClient_VEHICLE-SERVICE/nikzgs-Latitude-E5420 - registration status: 204

Answer 1

The problem was caused by VehicleController class methods:
#ResponseBody
#HystrixCommand(commandKey = "getAllVehicles", groupKey = "Vehicles", fallbackMethod = "returnErrorMessage")
#RequestMapping(value = "/vehicles", method = RequestMethod.GET)
public VehicleSummary getAllVehicles() {
return vehicleService.getAllVehicles();
}
#HystrixCommand
private String returnErrorMessage() {
return "Fallback error message";
}
The problem was that Hystrix is trying to construct the response with returnErrorMessage() method which returns String and getAllVehicles() returns VehicleSummary class. Hence, it cannot cast String to VehicleSummary.
The correct way is to return the same class on the fallback:
#ResponseBody
#HystrixCommand(commandKey = "getAllVehicles", groupKey = "Vehicles", fallbackMethod = "returnErrorMessage")
#RequestMapping(value = "/vehicles", method = RequestMethod.GET)
public VehicleSummary getAllVehicles() {
return vehicleService.getAllVehicles();
}
#HystrixCommand
private VehicleSummary returnErrorMessage() {
return new VehicleSummary();
}