Issue 1:
I have searched the issues of this repository and believe that this is not a duplicate.

I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

Dubbo version: 2.7.1

Operating System version: mac 10.14

Java version: 12

Steps to reproduce this issue

Start Dubbo REST service, when request by browser is correct

Start another Dubbo by dubbo protocol, then reference dubbo rest alwasy exception with no provider.

If there is an exception, please attach the exception trace:

org.apache.dubbo.rpc.RpcException: Failed to invoke the method say in the service com.yuxiao.dubbo.demo.service.DemoService. No provider available for the service com.yuxiao.dubbo.demo.service.DemoService:1.0.1 from registry 127.0.0.1:2181 on the consumer 192.168.91.189 using the dubbo version 2.7.1. Please check if the providers have been started and registered.
at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.checkInvokers(AbstractClusterInvoker.java:265) ~[dubbo-2.7.1.jar:2.7.1]
at org.apache.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:57) ~[dubbo-2.7.1.jar:2.7.1]
at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:242) ~[dubbo-2.7.1.jar:2.7.1]
at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:76) ~[dubbo-2.7.1.jar:2.7.1]
at org.apache.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:57) ~[dubbo-2.7.1.jar:2.7.1]
at org.apache.dubbo.common.bytecode.proxy0.say(proxy0.java) ~[dubbo-2.7.1.jar:2.7.1]
at com.yuxiao.dubbo.demo.controller.DemoController.say(DemoController.java:17) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[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:567) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.17.jar:9.0.17]
at java.base/java.lang.Thread.run(Thread.java:835) ~[na:na]

Issue 2:
I have searched the issues of this repository and believe that this is not a duplicate.

I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

Dubbo version: 2.6.2

Operating System version: Win7

Java version: 1.8

Step to reproduce this issue

不支持同时存在一个异步引用和一个同步引用，dubbo注入两个对象的地址都是相同的，第一个如果是异步则两个都是异步。 第一如果是同步则两个都是同步

@Reference(async = true)
private DebugService ansyncDebugService;

@Reference(async = false)
private DebugService debugService;