3 files changed, 15 insertions, 6 deletions
diff --git a/Lib/concurrent/futures/_base.py b/Lib/concurrent/futures/_base.py
index acd05d0..c13b3b6 100644
--- a/Lib/concurrent/futures/_base.py
+++ b/Lib/concurrent/futures/_base.py
@@ -302,17 +302,20 @@ class Future(object):
         with self._condition:
             if self._state == FINISHED:
                 if self._exception:
-                    return '<Future at %s state=%s raised %s>' % (
-                        hex(id(self)),
+                    return '<%s at %#x state=%s raised %s>' % (
+                        self.__class__.__name__,
+                        id(self),
                         _STATE_TO_DESCRIPTION_MAP[self._state],
                         self._exception.__class__.__name__)
                 else:
-                    return '<Future at %s state=%s returned %s>' % (
-                        hex(id(self)),
+                    return '<%s at %#x state=%s returned %s>' % (
+                        self.__class__.__name__,
+                        id(self),
                         _STATE_TO_DESCRIPTION_MAP[self._state],
                         self._result.__class__.__name__)
-            return '<Future at %s state=%s>' % (
-                    hex(id(self)),
+            return '<%s at %#x state=%s>' % (
+                    self.__class__.__name__,
+                    id(self),
                    _STATE_TO_DESCRIPTION_MAP[self._state])
 
     def cancel(self):
diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
index 07b5225..1299390 100644
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -334,6 +334,9 @@ class ProcessPoolExecutor(_base.Executor):
         if max_workers is None:
             self._max_workers = os.cpu_count() or 1
         else:
+            if max_workers <= 0:
+                raise ValueError("max_workers must be greater than 0")
+
             self._max_workers = max_workers
 
         # Make the call queue slightly larger than the number of processes to
diff --git a/Lib/concurrent/futures/thread.py b/Lib/concurrent/futures/thread.py
index f9beb0f..8d6081c 100644
--- a/Lib/concurrent/futures/thread.py
+++ b/Lib/concurrent/futures/thread.py
@@ -87,6 +87,9 @@ class ThreadPoolExecutor(_base.Executor):
             max_workers: The maximum number of threads that can be used to
                 execute the given calls.
         """
+        if max_workers <= 0:
+            raise ValueError("max_workers must be greater than 0")
+
         self._max_workers = max_workers
         self._work_queue = queue.Queue()
         self._threads = set()