add exception traceback of remote function calling (#79)

* add traceback of remote function calling

* assert traceback information

parl/remote/remote_decorator.py

@@ -16,6 +16,7 @@ import numpy as np
 import pyarrow
 import threading
 import time
+import traceback
 import zmq
 from parl.remote import remote_constants
 from parl.utils import get_ip_address, logger, to_str, to_byte
@@ -179,7 +180,7 @@ def remote_class(cls):
 
                 except Exception as e:
                     error_str = str(e)
-                    logger.error(e)
+                    logger.error(error_str)
 
                     if type(e) == AttributeError:
                         self.reply_socket.send_multipart([
@@ -197,9 +198,12 @@ def remote_class(cls):
                             to_byte(error_str)
                         ])
                     else:
+                        traceback_str = str(traceback.format_exc())
+                        logger.error('traceback:\n{}'.format(traceback_str))
                         self.reply_socket.send_multipart([
                             remote_constants.EXCEPTION_TAG,
-                            to_byte(error_str)
+                            to_byte(error_str + '\ntraceback:\n' +
+                                    traceback_str)
                         ])
 
                     continue

parl/remote/tests/remote_test.py

@@ -50,6 +50,9 @@ class Simulator:
         value += 1
         return value
 
+    def will_raise_exeception_func(self):
+        x = 1 / 0
+
 
 class TestRemote(unittest.TestCase):
     def _setUp(self, server_port):
@@ -91,7 +94,8 @@ class TestRemote(unittest.TestCase):
 
         try:
             remote_sim.get_arg3()
-        except RemoteAttributeError:
+        except RemoteAttributeError as e:
+            logger.info('Expected exception: {}'.format(e))
             # expected
             return
 
@@ -105,7 +109,8 @@ class TestRemote(unittest.TestCase):
 
         try:
             remote_sim.set_arg3(3)
-        except RemoteAttributeError:
+        except RemoteAttributeError as e:
+            logger.info('Expected exception: {}'.format(e))
             # expected
             return
 
@@ -119,7 +124,8 @@ class TestRemote(unittest.TestCase):
 
         try:
             remote_sim.set_arg1(wrong_arg=1)
-        except RemoteError:
+        except RemoteError as e:
+            logger.info('Expected exception: {}'.format(e))
             # expected
             return
 
@@ -277,6 +283,22 @@ class TestRemote(unittest.TestCase):
         for t in threads:
             t.join()
 
+    def test_remote_object_with_call_raise_exception_function(self):
+        server_port = 17781
+        self._setUp(server_port)
+
+        remote_sim = self.remote_manager.get_remote()
+
+        try:
+            remote_sim.will_raise_exeception_func()
+        except RemoteError as e:
+            assert 'Traceback (most recent call last)' in str(e)
+            logger.info('Expected exception: {}'.format(e))
+            # expected
+            return
+
+        assert False
+
     def _run_remote_add(self, remote_sim):
         value = 0
         for i in range(1000):