Update app.py

app.py

@@ -96,7 +96,7 @@ def evaluate(
     subset: str,
     samples: str,
     pass_k: str="1,5,10",
-    parallel: int = None,
+    parallel: int = -1,
     min_time_limit: float = 1,
     max_as_limit: int = 30 * 1024,
     max_data_limit: int = 30 * 1024,
@@ -105,7 +105,7 @@ def evaluate(
     no_gt: bool = False,
 ):
     pass_k = [int(k.strip()) for k in pass_k.split(',') if k.strip().isdigit()]
-    if parallel is None:
+    if not parallel:
         n_workers = max(1, multiprocessing.cpu_count() // 2)
     else:
         n_workers = parallel