Fix process pool fallback on Python 3.10 (GH-2631)

In Python 3.10 the exception generated by creating a process pool on
a Python build that doesn't support this is now `NotImplementedError`

Commit history before merge:

* Fix process pool fallback on Python 3.10
* Update CHANGES.md
* Update CHANGES.md

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

diff --git a/CHANGES.md b/CHANGES.md
index 35024de724d4adfd0121b8f0da9289570475711e..db519ac6bbc9a636fc1dd90de43f04f53c5f1ee5 100644 (file)
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,11 @@
 # Change Log
 
 # Change Log
 

+## Unreleased
+
+### _Black_
+
+- Fixed Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
+

 ## 21.11b1
 
 ### _Black_
 ## 21.11b1
 
 ### _Black_

diff --git a/src/black/__init__.py b/src/black/__init__.py
index a5ddec9122105cae9393d126c92f3c3c5bfb3ec3..aa7970cfd6c443e90375e6c342185f74174dec4d 100644 (file)
--- a/src/black/__init__.py
+++ b/src/black/__init__.py
@@ -687,7 +687,7 @@ def reformat_many(
         worker_count = min(worker_count, 60)
     try:
         executor = ProcessPoolExecutor(max_workers=worker_count)
         worker_count = min(worker_count, 60)
     try:
         executor = ProcessPoolExecutor(max_workers=worker_count)

-    except (ImportError, OSError):
+    except (ImportError, NotImplementedError, OSError):

         # we arrive here if the underlying system does not support multi-processing
         # like in AWS Lambda or Termux, in which case we gracefully fallback to
         # a ThreadPoolExecutor with just a single worker (more workers would not do us
         # we arrive here if the underlying system does not support multi-processing
         # like in AWS Lambda or Termux, in which case we gracefully fallback to
         # a ThreadPoolExecutor with just a single worker (more workers would not do us