我正在使用版本为Edgware.SR3的Spring Cloud。我已经使用Spring Caching Abstraction实现了Caffine缓存。我们也在使用Hystrix。对于Hystrix，我们没有使用基于注释的方法。
以下是所需的代码。
UserRepositoryImpl.Java
//.. code
@Override
public Observable<Optional<List<User>>> getUserList(final String status) {
return new HystrixObservableCommand<Optional<List<User>>>(
HystrixObservableCommand.Setter.withGroupKey(
hystrixCommandGroupKey).andCommandKey(
HystrixCommandKey.Factory.asKey("getUserList"))) {
@Override
protected Observable<Optional<List<User>>> construct() {
return Observable.create((Subscriber<? super Optional<List<User>>> subscriber) -> {
try {
if (!subscriber.isUnsubscribed()) {
System.out.println("##############Database Call getUserList");
//.. Database call or http call
}
} catch (Exception ex) {
//.. Some exception Handling
} finally {
if (!subscriber.isUnsubscribed()) {
subscriber.onCompleted();
}
}
});
}
@Override
protected Observable<Optional<List<User>>> resumeWithFallback() {
return Observable.create((Subscriber<? super Optional<List<User>>> subscriber) -> {
try {
if (!subscriber.isUnsubscribed()) {
System.out.println("##############Database Call getUserList");
//.. Database call or http call
}
} catch (Exception ex) {
//.. Some exception Handling
} finally {
if (!subscriber.isUnsubscribed()) {
subscriber.onCompleted();
}
}
});
}
}.toObservable();
}
//.. code
UserService.java
//.. code
@Cacheable(cacheNames = "UserListCache", key = "#status")
public Observable<Optional<List<User>>> listUsersAsync(final String status){
return userRepository.getUserList(status);
}
//.. code
获得以下异常。
com.netflix.hystrix.exception.HystrixRuntimeException: getUserList command executed multiple times - this is not permitted.
at com.netflix.hystrix.AbstractCommand$7.call(AbstractCommand.java:461) ~[hystrix-core-1.5.12.jar:1.5.12]
at com.netflix.hystrix.AbstractCommand$7.call(AbstractCommand.java:454) ~[hystrix-core-1.5.12.jar:1.5.12]
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46) [rxjava-1.2.0.jar:1.2.0]
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35) [rxjava-1.2.0.jar:1.2.0]
at rx.Observable.subscribe(Observable.java:10247) ~[rxjava-1.2.0.jar:1.2.0]
at rx.Observable.subscribe(Observable.java:10214) ~[rxjava-1.2.0.jar:1.2.0]
at rx.Observable.subscribe(Observable.java:10054) ~[rxjava-1.2.0.jar:1.2.0]
at com.j2.billing.mvc.controller.AdminController.listUsers(AdminController.java:68) ~[main/:na]
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:205) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at com.j2.billing.mvc.filter.AuthenticationFilter.doFilter(AuthenticationFilter.java:110) ~[main/:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110) ~[spring-boot-actuator-1.5.6.RELEASE.jar:1.5.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:96) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:106) ~[spring-boot-actuator-1.5.6.RELEASE.jar:1.5.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.10.RELEASE.jar:4.3.10.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) ~[na:1.8.0_65]
at java.util.concurrent.ThreadPoolExecutor$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-8.5.6.jar:8.5.6]
at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_65]
Caused by: java.lang.IllegalStateException: This instance can only be executed once. Please instantiate a new instance.
at com.netflix.hystrix.AbstractCommand$7.call(AbstractCommand.java:459) ~[hystrix-core-1.5.12.jar:1.5.12]
... 80 common frames omitted
我有一些使用Observable（没有HystrixObservableCommand）的其他缓存方法没有任何问题。
有人可以帮我解决这个问题吗？
答案 0 :(得分：0)
您正在缓存Observable创建的HystrixObservableCommand对象。这个observable执行它在订阅时包含的HystrixCommand。
因此，如果您缓存Observable并在以后重复使用它，将导致多次使用相同的HystrixCommand，并且不允许这样做。
您需要缓存的内容是Optional<List<User>>，而不是Observable<Optional<List<User>>>。