do not add error_summary for debug log messages

We catch exceptions and log debug messages a lot, which results in extra
occurrences of the exception when we don't need them.

Change-Id: I4dd3bf65fb456afc07a8fa7d0c9869bcc266b800
Related-Bug: #1696213
Related-Bug: #1696855
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

oslo_log/formatters.py

@@ -98,11 +98,16 @@ def _get_error_summary(record):
 
     If there is no active exception, return the default.
 
+    If the record is being logged at debug level, return an empty
+    string.
+
     If there is an active exception, format it and return the
     resulting string.
 
     """
     error_summary = ''
+    if record.levelno == logging.DEBUG:
+        return ''
 
     if record.exc_info:
         # Save the exception we were given so we can include the

oslo_log/tests/unit/test_log.py

@@ -577,7 +577,7 @@ class FluentFormatterTestCase(LogTestBase):
         try:
             raise RuntimeError('test_exception')
         except RuntimeError:
-            self.log.debug('testing', context=local_context)
+            self.log.info('testing', context=local_context)
         data = jsonutils.loads(self.stream.getvalue())
         self.assertIn('error_summary', data)
         self.assertEqual('RuntimeError: test_exception',