fix for issue #9047

pypa · Oct 25, 2020 · cf7e150 · cf7e150
1 parent 08c99b6
commit cf7e150
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diff --git a/news/9047.bugfix.rst b/news/9047.bugfix.rst
@@ -0,0 +1 @@
+Check for operativeness of multiprocessing. This takes care of systems where multiprocessing seems available but really is not.
diff --git a/src/pip/_internal/utils/parallel.py b/src/pip/_internal/utils/parallel.py
@@ -43,7 +43,12 @@
 except ImportError:
     LACK_SEM_OPEN = True
 else:
-    LACK_SEM_OPEN = False
+    try:
+        ProcessPool()
+    except OSError:
+        LACK_SEM_OPEN = True
+    else:
+        LACK_SEM_OPEN = False
 
 # Incredibly large timeout to work around bpo-8296 on Python 2.
 TIMEOUT = 2000000