Revert "Support accessing underlying attributes in RayTaskErrors (#9210)" (#9263)

This reverts commit 21cad5250a.

python/ray/_raylet.pyx

@@ -486,10 +486,10 @@ cdef execute_task(
             if isinstance(error, RayTaskError):
                 # Avoid recursive nesting of RayTaskError.
                 failure_object = RayTaskError(function_name, backtrace,
-                                              error.cause, proctitle=title)
+                                              error.cause_cls, proctitle=title)
             else:
                 failure_object = RayTaskError(function_name, backtrace,
-                                              error, proctitle=title)
+                                              error.__class__, proctitle=title)
             errors = []
             for _ in range(c_return_ids.size()):
                 errors.append(failure_object)

python/ray/exceptions.py

@@ -41,12 +41,17 @@ class RayTaskError(RayError):
     retrieved from the object store, the Python method that retrieved it checks
     to see if the object is a RayTaskError and if it is then an exception is
     thrown propagating the error message.
+
+    Attributes:
+        function_name (str): The name of the function that failed and produced
+            the RayTaskError.
+        traceback_str (str): The traceback from the exception.
     """
 
     def __init__(self,
                  function_name,
                  traceback_str,
-                 cause,
+                 cause_cls,
                  proctitle=None,
                  pid=None,
                  ip=None):
@@ -59,43 +64,34 @@ class RayTaskError(RayError):
         self.ip = ip or ray.services.get_node_ip_address()
         self.function_name = function_name
         self.traceback_str = traceback_str
-        # TODO(edoakes): should we handle non-serializable exception objects?
-        self.cause = cause
+        self.cause_cls = cause_cls
         assert traceback_str is not None
 
     def as_instanceof_cause(self):
-        """Returns an exception that is an instance of the cause's class.
+        """Returns copy that is an instance of the cause's Python class.
 
         The returned exception will inherit from both RayTaskError and the
-        cause class and will contain all of the attributes of the cause
-        exception.
+        cause class.
         """
 
-        cause_cls = self.cause.__class__
-        if issubclass(RayTaskError, cause_cls):
+        if issubclass(RayTaskError, self.cause_cls):
             return self  # already satisfied
 
-        if issubclass(cause_cls, RayError):
+        if issubclass(self.cause_cls, RayError):
             return self  # don't try to wrap ray internal errors
 
-        cause = self.cause
-        error_msg = str(self)
+        class cls(RayTaskError, self.cause_cls):
+            def __init__(self, function_name, traceback_str, cause_cls,
+                         proctitle, pid, ip):
+                RayTaskError.__init__(self, function_name, traceback_str,
+                                      cause_cls, proctitle, pid, ip)
 
-        class cls(RayTaskError, cause_cls):
-            def __init__(self):
-                pass
-
-            def __getattr__(self, name):
-                return getattr(cause, name)
-
-            def __str__(self):
-                return error_msg
-
-        name = "RayTaskError({})".format(cause_cls.__name__)
+        name = "RayTaskError({})".format(self.cause_cls.__name__)
         cls.__name__ = name
         cls.__qualname__ = name
 
-        return cls()
+        return cls(self.function_name, self.traceback_str, self.cause_cls,
+                   self.proctitle, self.pid, self.ip)
 
     def __str__(self):
         """Format a RayTaskError as a string."""

python/ray/tests/test_failure.py

@@ -63,12 +63,7 @@ def test_failed_task(ray_start_regular):
             assert False
 
     class CustomException(ValueError):
-        def __init__(self, msg):
-            super().__init__(msg)
-            self.field = 1
-
-        def f(self):
-            return 2
+        pass
 
     @ray.remote
     def f():
@@ -78,12 +73,9 @@ def test_failed_task(ray_start_regular):
         ray.get(f.remote())
     except Exception as e:
         assert "This function failed." in str(e)
-        assert isinstance(e, ValueError)
         assert isinstance(e, CustomException)
         assert isinstance(e, ray.exceptions.RayTaskError)
         assert "RayTaskError(CustomException)" in repr(e)
-        assert e.field == 1
-        assert e.f() == 2
     else:
         # ray.get should throw an exception.
         assert False