[apache/dubbo]getMethodParameter(java.lang.String, java.lang.String, java.lang.String)并发修改导致空指针异常

• Dubbo version: 2.7.13
• Operating System version: Mac OS、Linux
• Java version: 1.8
• 方法名 org.apache.dubbo.metadata.MetadataInfo.ServiceInfo#getMethodParameter(java.lang.String, java.lang.String, java.lang.String) Steps to reproduce this issue

  出问题的代码 if (methodParams == null) { methodParams = URL.toMethodParameters(params); consumerMethodParams = URL.toMethodParameters(consumerParams); } 修改为 Map<String, Map<String, String>> temp = methodParams; if (methodParams == null) { methodParams = URL.toMethodParameters(params); if(temp == null){ try { Thread.sleep(1000*3); } catch (InterruptedException e) { e.printStackTrace(); } } consumerMethodParams = URL.toMethodParameters(consumerParams); }

  1. 多线程问题较难复现，采用修改代码的形式模拟
  2. 修改代码
  3. 在sleep的时间内进行两次请求，第一个请求进入sleep，第二个请求出现空指针异常

由于methodParams已经不为空，consumerMethodParams没有被初始化，执行到342行代码时发生空指针

Caused by: java.lang.NullPointerException: null
    at org.apache.dubbo.metadata.MetadataInfo$ServiceInfo.getMethodParameter(MetadataInfo.java:353)
    at org.apache.dubbo.metadata.MetadataInfo$ServiceInfo.getMethodParameter(MetadataInfo.java:344)
    at org.apache.dubbo.registry.client.InstanceAddressURL.getServiceMethodParameter(InstanceAddressURL.java:143)
    at org.apache.dubbo.registry.client.InstanceAddressURL.getMethodParameter(InstanceAddressURL.java:156)
    at org.apache.dubbo.common.URL.getMethodParameter(URL.java:881)
    at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.initLoadBalance(AbstractClusterInvoker.java:314)
    at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:263)
    at org.apache.dubbo.rpc.cluster.interceptor.ClusterInterceptor.intercept(ClusterInterceptor.java:47)
    at org.apache.dubbo.rpc.cluster.support.wrapper.AbstractCluster$InterceptorInvokerNode.invoke(AbstractCluster.java:92)
    at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:93)
    at org.apache.dubbo.registry.client.migration.ServiceDiscoveryMigrationInvoker.invoke(ServiceDiscoveryMigrationInvoker.java:59)
    at org.apache.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:96)
    at org.apache.dubbo.common.bytecode.proxy1.sayHello(proxy1.java)