Issue #11569: use absolute path to the sysctl command in multiprocessing to

ensure that it will be found regardless of the shell PATH. This ensures
that multiprocessing.cpu_count works on default installs of MacOSX.

Lib/multiprocessing/__init__.py

@@ -115,8 +115,11 @@ def cpu_count():
         except (ValueError, KeyError):
             num = 0
     elif 'bsd' in sys.platform or sys.platform == 'darwin':
+        comm = '/sbin/sysctl -n hw.ncpu'
+        if sys.platform == 'darwin':
+            comm = '/usr' + comm
         try:
-            with os.popen('sysctl -n hw.ncpu') as p:
+            with os.popen(comm) as p:
                 num = int(p.read())
         except ValueError:
             num = 0

Misc/ACKS

@@ -583,6 +583,7 @@ Tim Northover
 Joe Norton
 Neal Norwitz
 Michal Nowikowski
+Steffen Daode Nurpmeso
 Nigel O'Brian
 Kevin O'Connor
 Tim O'Malley

Misc/NEWS

@@ -40,6 +40,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #11569: use absolute path to the sysctl command in multiprocessing to
+  ensure that it will be found regardless of the shell PATH. This ensures
+  that multiprocessing.cpu_count works on default installs of MacOSX.
+
 - Issue #11501: disutils.archive_utils.make_zipfile no longer fails if zlib is
   not installed. Instead, the zipfile.ZIP_STORED compression is used to create
   the ZipFile. Patch by Natalia B. Bidart.