[jira] [Created] (HADOOP-18814) Direct class cast may cause ClassCastException in TestRPC#testReaderExceptions

["ConfX (Jira)" <ji...@apache.org>]

ConfX created HADOOP-18814:
------------------------------

             Summary: Direct class cast may cause ClassCastException in TestRPC#testReaderExceptions
                 Key: HADOOP-18814
                 URL: https://issues.apache.org/jira/browse/HADOOP-18814
             Project: Hadoop Common
          Issue Type: Bug
          Components: conf, ipc
            Reporter: ConfX
         Attachments: reproduce.sh

h2. 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{}}}.
h2. 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 RemoteExceptionassertEquals(reqName, expectedIOE, re.unwrapRemoteException());
      }
h2. How to reproduce:

(1) Set {{hadoop.security.authentication}} to {{kerberos}}
(2) Run test {{TestRPC#testReaderExceptions}}
{{}}
h2. 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.hadoop.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)                                         
h2. 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");
    }
  }



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