diff --git a/flaml/tune/tune.py b/flaml/tune/tune.py
index 7b5b2a62f..07e29d566 100644
--- a/flaml/tune/tune.py
+++ b/flaml/tune/tune.py
@@ -492,9 +492,7 @@ def run(
 
                 SearchAlgorithm = BlendSearch
                 logger.info(
-                    "Using search algorithm {}.".format(
-                        SearchAlgorithm.__class__.__name__
-                    )
+                    "Using search algorithm {}.".format(SearchAlgorithm.__name__)
                 )
             except ImportError:
                 SearchAlgorithm = CFO
@@ -504,9 +502,7 @@ def run(
             metric = metric or DEFAULT_METRIC
         else:
             SearchAlgorithm = CFO
-            logger.info(
-                "Using search algorithm {}.".format(SearchAlgorithm.__class__.__name__)
-            )
+            logger.info("Using search algorithm {}.".format(SearchAlgorithm.__name__))
             metric = lexico_objectives["metrics"][0] or DEFAULT_METRIC
         search_alg = SearchAlgorithm(
             metric=metric,
@@ -675,14 +671,14 @@ def run(
                     num_trials = 0
                     if time_budget_s is None:
                         time_budget_s = np.inf
-                    fail = 0
-                    ub = (
+                    num_failures = 0
+                    upperbound_num_failures = (
                         len(evaluated_rewards) if evaluated_rewards else 0
                     ) + max_failure
                     while (
                         time.time() - time_start < time_budget_s
                         and (num_samples < 0 or num_trials < num_samples)
-                        and fail < ub
+                        and num_failures < upperbound_num_failures
                     ):
                         while len(_runner.running_trials) < n_concurrent_trials:
                             # suggest trials for spark
@@ -690,9 +686,9 @@ def run(
                             if trial_next:
                                 num_trials += 1
                             else:
-                                fail += 1  # break with ub consecutive failures
-                                logger.debug(f"consecutive failures is {fail}")
-                                if fail >= ub:
+                                num_failures += 1  # break with upperbound_num_failures consecutive failures
+                                logger.debug(f"consecutive failures is {num_failures}")
+                                if num_failures >= upperbound_num_failures:
                                     break
                         trials_to_run = _runner.running_trials
                         if not trials_to_run:
@@ -730,7 +726,7 @@ def run(
                                     )
                                     report(_metric=result)
                             _runner.stop_trial(trial_to_run)
-                        fail = 0
+                        num_failures = 0
                     analysis = ExperimentAnalysis(
                         _runner.get_trials(),
                         metric=metric,
@@ -766,12 +762,14 @@ def run(
         num_trials = 0
         if time_budget_s is None:
             time_budget_s = np.inf
-        fail = 0
-        ub = (len(evaluated_rewards) if evaluated_rewards else 0) + max_failure
+        num_failures = 0
+        upperbound_num_failures = (
+            len(evaluated_rewards) if evaluated_rewards else 0
+        ) + max_failure
         while (
             time.time() - time_start < time_budget_s
             and (num_samples < 0 or num_trials < num_samples)
-            and fail < ub
+            and num_failures < upperbound_num_failures
         ):
             trial_to_run = _runner.step()
             if trial_to_run:
@@ -789,10 +787,11 @@ def run(
                     else:
                         report(_metric=result)
                 _runner.stop_trial(trial_to_run)
-                fail = 0
+                num_failures = 0
             else:
-                fail += 1  # break with ub consecutive failures
-        if fail == ub:
+                # break with upperbound_num_failures consecutive failures
+                num_failures += 1
+        if num_failures == upperbound_num_failures:
             logger.warning(
                 f"fail to sample a trial for {max_failure} times in a row, stopping."
             )