[SPARK-19505][PYTHON] AttributeError on Exception.message in Python3

## What changes were proposed in this pull request?

Added `util._message_exception` helper to use `str(e)` when `e.message` is unavailable (Python3).  Grepped for all occurrences of `.message` in `pyspark/` and these were the only occurrences.

## How was this patch tested?

- Doctests for helper function

## Legal

This is my original work and I license the work to the project under the project’s open source license.

Author: David Gingrich <david@textio.com>

Closes #16845 from dgingrich/topic-spark-19505-py3-exceptions.

1 files changed, 3 insertions, 1 deletions

diff --git a/python/pyspark/broadcast.py b/python/pyspark/broadcast.py
index 74dee14207..b1b59f73d6 100644
--- a/python/pyspark/broadcast.py
+++ b/python/pyspark/broadcast.py
@@ -21,6 +21,7 @@ import gc
 from tempfile import NamedTemporaryFile
 
 from pyspark.cloudpickle import print_exec
+from pyspark.util import _exception_message
 
 if sys.version < '3':
     import cPickle as pickle
@@ -82,7 +83,8 @@ class Broadcast(object):
         except pickle.PickleError:
             raise
         except Exception as e:
-            msg = "Could not serialize broadcast: " + e.__class__.__name__ + ": " + e.message
+            msg = "Could not serialize broadcast: %s: %s" \
+                  % (e.__class__.__name__, _exception_message(e))
             print_exec(sys.stderr)
             raise pickle.PicklingError(msg)
         f.close()