Added default number of max workers for Python < 3.5

rollbar/lib/thread_pool.py

@@ -1,4 +1,6 @@
 import logging
+import os
+import sys
 from concurrent.futures import ThreadPoolExecutor
 
 _pool = None  # type: ThreadPoolExecutor|None
@@ -10,8 +12,13 @@ def init_pool(max_workers):
     """
     Creates the thread pool with the max workers.
 
-    :type max_workers: int
+    :type max_workers: int|None
+    :param max_workers: If max_workers is None it will use the logic from the standard library to calculate the number
+                        of threads. However, we ported the logic from Python 3.5 to earlier versions.
     """
+    if max_workers is None and sys.version_info < (3, 5):
+        max_workers = (os.cpu_count() or 1) * 5
+
     global _pool
     _pool = ThreadPoolExecutor(max_workers)