[Python-checkins] cpython: Issue #17914: Use os.cpu_count() instead of multiprocessing.cpu_count() where

[charles-francois.natali]

http://hg.python.org/cpython/rev/6a0437adafbd
changeset:   84355:6a0437adafbd
user:        Charles-François Natali <cf.natali at gmail.com>
date:        Fri Jun 28 19:25:45 2013 +0200
summary:
  Issue #17914: Use os.cpu_count() instead of multiprocessing.cpu_count() where
applicable.

files:
  Doc/library/multiprocessing.rst   |  2 +-
  Lib/concurrent/futures/process.py |  2 +-
  Lib/multiprocessing/pool.py       |  8 +++-----
  Lib/test/regrtest.py              |  8 ++------
  4 files changed, 7 insertions(+), 13 deletions(-)


diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -1664,7 +1664,7 @@
    callbacks and has a parallel map implementation.
 
    *processes* is the number of worker processes to use.  If *processes* is
-   ``None`` then the number returned by :func:`cpu_count` is used.  If
+   ``None`` then the number returned by :func:`os.cpu_count` is used.  If
    *initializer* is not ``None`` then each worker process will call
    ``initializer(*initargs)`` when it starts.
 
diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
--- a/Lib/concurrent/futures/process.py
+++ b/Lib/concurrent/futures/process.py
@@ -331,7 +331,7 @@
         _check_system_limits()
 
         if max_workers is None:
-            self._max_workers = multiprocessing.cpu_count()
+            self._max_workers = os.cpu_count() or 1
         else:
             self._max_workers = max_workers
 
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -17,10 +17,11 @@
 import queue
 import itertools
 import collections
+import os
 import time
 import traceback
 
-from multiprocessing import Process, cpu_count, TimeoutError
+from multiprocessing import Process, TimeoutError
 from multiprocessing.util import Finalize, debug
 
 #
@@ -147,10 +148,7 @@
         self._initargs = initargs
 
         if processes is None:
-            try:
-                processes = cpu_count()
-            except NotImplementedError:
-                processes = 1
+            processes = os.cpu_count() or 1
         if processes < 1:
             raise ValueError("Number of processes must be at least 1")
 
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -508,12 +508,8 @@
         elif o in ('-j', '--multiprocess'):
             use_mp = int(a)
             if use_mp <= 0:
-                try:
-                    import multiprocessing
-                    # Use all cores + extras for tests that like to sleep
-                    use_mp = 2 + multiprocessing.cpu_count()
-                except (ImportError, NotImplementedError):
-                    use_mp = 3
+                # Use all cores + extras for tests that like to sleep
+                use_mp = 2 + (os.cpu_count() or 1)
             if use_mp == 1:
                 use_mp = None
         elif o == '--header':

-- 
Repository URL: http://hg.python.org/cpython