[HADOOP-18814] Direct class cast causes ClassCastException in TestRPC#testReaderExceptions - ASF JIRA

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Details

Type: Bug
Status: Open
Priority: Critical
Resolution: Unresolved
Affects Version/s: None
Fix Version/s: None
Component/s: conf, ipc
Labels:
- pull-request-available

Description

What happened:

Test TestRPC#testReaderExceptions assumes there is a RemoteException has been thrown and directly cast the root cause of ServiceException to RemoteException. But this cast may lead to ClassCastException when the root cause exception is not RemoteException.

Buggy code:

@Test (timeout=30000)
public void testReaderExceptions() throws Exception {
      ...
      try {
        FakeRequestClass.exception = doDisconnect ? rseFatal : rseError;
        proxy.ping(null, newEmptyRequest());
        fail(reqName + " didn't fail");
      } catch (ServiceException e) {
        RemoteException re = (RemoteException)e.getCause();       // <--- Here the test assumes the root cause is RemoteException
        assertEquals(reqName, expectedIOE, re.unwrapRemoteException());
      }

How to reproduce:

(1) Set hadoop.security.authentication to kerberos
(2) Run test TestRPC#testReaderExceptions

Stack trace:

java.lang.ClassCastException: class java.io.IOException cannot be cast to class org.apache.hadoop.ipc.RemoteException (java.io.IOException is in module java.base of loader 'bootstrap'; org.apache.had
oop.ipc.RemoteException is in unnamed module of loader 'app')                  
        at org.apache.hadoop.ipc.TestRPC.testReaderExceptions(TestRPC.java:1742)                                                                                                                       
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)                              
        at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
        at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)     
        at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
        at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
        at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:299)
        at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:293)                                                                                          
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)                      
        at java.base/java.lang.Thread.run(Thread.java:829)

Fix:

A better way to do is to firstly check whether the root cause is RemoteException, if not, fail the test rather than causing the CastClassException:

  try {
    FakeRequestClass.exception = doDisconnect ? rseFatal : rseError;
    proxy.ping(null, newEmptyRequest());
    fail(reqName + " didn't fail");
  } catch (ServiceException e) {
    if (e.getCause() instanceof RemoteException) {
      RemoteException re = (RemoteException)e.getCause();
      assertEquals(reqName, expectedIOE, re.unwrapRemoteException());
    } else {
      fail(reqName + " didn't fail with RemoteException");
    }
  }