getMethodParameter(java.lang.String, java.lang.String, java.lang.String)并发修改导致空指针异常

[Holmesus]

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

Environment

• 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

Expected Behavior

正常执行

Actual Behavior

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)

[neighbor-uncleWang]

I think I can solve it.Please assign it to me.

[Holmesus]

I think I can solve it.Please assign it to me.

期待您的回复，隔壁老王同学

[neighbor-uncleWang]

@Holmesus 能不能提供一个可以重现的测试用例呢？？就像MetadataInfoTest里面的方法一样

[neighbor-uncleWang]

@Holmesus 我想用CAS能解决这个问题。或者两个if判断

[Holmesus]

@Holmesus 能不能提供一个可以重现的测试用例呢？？就像MetadataInfoTest里面的方法一样

这个不太好复现，我用多线程只复现了一次，是通过修改MetadataInfo的源码稳定重现的，把MetadataInfo复制一份放在IDE中，用sleep让后来的线程先执行后续的代码

[CrazyHZM]

@neighbor-uncleWang
Any progress ?

[wangchengming666]

@neighbor-uncleWang Any progress ?

@CrazyHZM I can fix it.

[neighbor-uncleWang]

@neighbor-uncleWang 有进展吗？

@CrazyHZM 我可以修复它。
@wangchengming666 哈喽，问题搞定了吗？？前段时间接入内网，一下子不能访问github了。今天才搞定，能登录上来。

[chickenlj]

This issue has been completely fixed in the latest 3.x release.