improved error handling in perf test framework

Signed-off-by: George Pisaltu <gpl@amazon.com>

tests/framework/matrix.py

@@ -7,6 +7,8 @@
 """
 
 import os
+import sys
+import traceback
 from framework.artifacts import ARTIFACTS_LOCAL_ROOT
 from framework.utils import ExceptionAggregator
 
@@ -115,8 +117,10 @@ def _backtrack(self, test_fn, cartesian_product):
         if len(self._sets) == len(cartesian_product):
             try:
                 self._run_test_fn(cartesian_product, test_fn)
-            except Exception as err:  # pylint: disable=W0703
-                self._failure_aggregator.add_row(err)
+            except Exception as _err:  # pylint: disable=W0703
+                self._failure_aggregator.add_row(
+                    "".join(traceback.format_exception(*sys.exc_info()))
+                )
             return
 
         current_set = self._sets[self._set_index]

tests/framework/utils.py

@@ -11,6 +11,7 @@
 import threading
 import typing
 import time
+
 from collections import namedtuple, defaultdict
 import psutil
 from retry import retry
@@ -287,7 +288,7 @@ def has_any(self) -> bool:
 
     def __str__(self):
         """Return custom as string implementation."""
-        return "\n".join(self.failures)
+        return "\n\n".join(self.failures)
 
 
 def search_output_from_cmd(cmd: str,