Issue #23530: Improve os.cpu_count() description.
Patch by Julian Taylor.
diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 8703f8f..e74430d 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -869,8 +869,13 @@
.. function:: cpu_count()
- Return the number of CPUs in the system. May raise
- :exc:`NotImplementedError`.
+ Return the number of CPUs in the system.
+
+ This number is not equivalent to the number of CPUs the current process can
+ use. The number of usable CPUs can be obtained with
+ ``len(os.sched_getaffinity(0))``
+
+ May raise :exc:`NotImplementedError`.
.. seealso::
:func:`os.cpu_count`
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 16e5019..0acb8a5 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -3596,6 +3596,11 @@
Return the number of CPUs in the system. Returns None if undetermined.
+ This number is not equivalent to the number of CPUs the current process can
+ use. The number of usable CPUs can be obtained with
+ ``len(os.sched_getaffinity(0))``
+
+
.. versionadded:: 3.4
diff --git a/Misc/ACKS b/Misc/ACKS
index 8a007ea..e4ba783 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1385,6 +1385,7 @@
Christian Tanzer
Steven Taschuk
Amy Taylor
+Julian Taylor
Monty Taylor
Anatoly Techtonik
Gustavo Temple
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index ec8c526..23d74a3 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -5760,7 +5760,7 @@
pid: pid_t
/
-Return the affinity of the process identified by pid.
+Return the affinity of the process identified by pid (or the current process if zero).
The affinity is returned as a set of CPU identifiers.
[clinic start generated code]*/
@@ -11201,7 +11201,9 @@
/*[clinic input]
os.cpu_count
-Return the number of CPUs in the system; return None if indeterminable.
+Return the number of CPUs in the system; return None if indeterminable. This
+number is not equivalent to the number of CPUs the current process can use.
+The number of usable CPUs can be obtained with ``len(os.sched_getaffinity(0))``
[clinic start generated code]*/
static PyObject *