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>
psf · Nov 20, 2021 · 05954c0 · 05954c0
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,5 +1,11 @@
 # Change Log
 
+## Unreleased
+
+### _Black_
+
+- Fixed Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
+
 ## 21.11b1
 
 ### _Black_

diff --git 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)
-    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