Issue #12655: Instead of requiring a custom type, os.sched_getaffinity and

os.sched_setaffinity now use regular sets of integers to represent the
CPUs a process is restricted to.

Doc/library/os.rst

@@ -3141,47 +3141,17 @@ operating system.
    Voluntarily relinquish the CPU.
 
 
-.. class:: cpu_set(ncpus)
-
-   :class:`cpu_set` represents a set of CPUs on which a process is eligible to
-   run. *ncpus* is the number of CPUs the set should describe. Methods on
-   :class:`cpu_set` allow CPUs to be add or removed.
-
-   :class:`cpu_set` supports the AND, OR, and XOR bitwise operations. For
-   example, given two cpu_sets, ``one`` and ``two``, ``one | two`` returns a
-   :class:`cpu_set` containing the cpus enabled both in ``one`` and ``two``.
-
-   .. method:: set(i)
-
-      Enable CPU *i*.
-
-   .. method:: clear(i)
-
-      Remove CPU *i*.
-
-   .. method:: isset(i)
-
-      Return ``True`` if CPU *i* is enabled in the set.
-
-   .. method:: count()
-
-      Return the number of enabled CPUs in the set.
-
-   .. method:: zero()
-
-      Clear the set completely.
-
-
 .. function:: sched_setaffinity(pid, mask)
 
-   Restrict the process with PID *pid* to a set of CPUs. *mask* is a
-   :class:`cpu_set` instance.
+   Restrict the process with PID *pid* (or the current process if zero) to a
+   set of CPUs.  *mask* is an iterable of integers representing the set of
+   CPUs to which the process should be restricted.
 
 
-.. function:: sched_getaffinity(pid, size)
+.. function:: sched_getaffinity(pid)
 
-   Return the :class:`cpu_set` the process with PID *pid* is restricted to. The
-   result will contain *size* CPUs.
+   Return the set of CPUs the process with PID *pid* (or the current process
+   if zero) is restricted to.
 
 
 .. _os-path:

Lib/test/test_posix.py

@@ -855,7 +855,7 @@ class PosixTester(unittest.TestCase):
 
     requires_sched_h = unittest.skipUnless(hasattr(posix, 'sched_yield'),
                                            "don't have scheduling support")
-    requires_sched_affinity = unittest.skipUnless(hasattr(posix, 'cpu_set'),
+    requires_sched_affinity = unittest.skipUnless(hasattr(posix, 'sched_setaffinity'),
                                                   "don't have sched affinity support")
 
     @requires_sched_h
@@ -936,83 +936,28 @@ class PosixTester(unittest.TestCase):
         self.assertLess(interval, 1.)
 
     @requires_sched_affinity
-    def test_sched_affinity(self):
-        mask = posix.sched_getaffinity(0, 1024)
-        self.assertGreaterEqual(mask.count(), 1)
-        self.assertIsInstance(mask, posix.cpu_set)
-        self.assertRaises(OSError, posix.sched_getaffinity, -1, 1024)
-        empty = posix.cpu_set(10)
-        posix.sched_setaffinity(0, mask)
-        self.assertRaises(OSError, posix.sched_setaffinity, 0, empty)
-        self.assertRaises(OSError, posix.sched_setaffinity, -1, mask)
-
-    @requires_sched_affinity
-    def test_cpu_set_basic(self):
-        s = posix.cpu_set(10)
-        self.assertEqual(len(s), 10)
-        self.assertEqual(s.count(), 0)
-        s.set(0)
-        s.set(9)
-        self.assertTrue(s.isset(0))
-        self.assertTrue(s.isset(9))
-        self.assertFalse(s.isset(5))
-        self.assertEqual(s.count(), 2)
-        s.clear(0)
-        self.assertFalse(s.isset(0))
-        self.assertEqual(s.count(), 1)
-        s.zero()
-        self.assertFalse(s.isset(0))
-        self.assertFalse(s.isset(9))
-        self.assertEqual(s.count(), 0)
-        self.assertRaises(ValueError, s.set, -1)
-        self.assertRaises(ValueError, s.set, 10)
-        self.assertRaises(ValueError, s.clear, -1)
-        self.assertRaises(ValueError, s.clear, 10)
-        self.assertRaises(ValueError, s.isset, -1)
-        self.assertRaises(ValueError, s.isset, 10)
-
-    @requires_sched_affinity
-    def test_cpu_set_cmp(self):
-        self.assertNotEqual(posix.cpu_set(11), posix.cpu_set(12))
-        l = posix.cpu_set(10)
-        r = posix.cpu_set(10)
-        self.assertEqual(l, r)
-        l.set(1)
-        self.assertNotEqual(l, r)
-        r.set(1)
-        self.assertEqual(l, r)
-
-    @requires_sched_affinity
-    def test_cpu_set_bitwise(self):
-        l = posix.cpu_set(5)
-        l.set(0)
-        l.set(1)
-        r = posix.cpu_set(5)
-        r.set(1)
-        r.set(2)
-        b = l & r
-        self.assertEqual(b.count(), 1)
-        self.assertTrue(b.isset(1))
-        b = l | r
-        self.assertEqual(b.count(), 3)
-        self.assertTrue(b.isset(0))
-        self.assertTrue(b.isset(1))
-        self.assertTrue(b.isset(2))
-        b = l ^ r
-        self.assertEqual(b.count(), 2)
-        self.assertTrue(b.isset(0))
-        self.assertFalse(b.isset(1))
-        self.assertTrue(b.isset(2))
-        b = l
-        b |= r
-        self.assertIs(b, l)
-        self.assertEqual(l.count(), 3)
+    def test_sched_getaffinity(self):
+        mask = posix.sched_getaffinity(0)
+        self.assertIsInstance(mask, set)
+        self.assertGreaterEqual(len(mask), 1)
+        self.assertRaises(OSError, posix.sched_getaffinity, -1)
+        for cpu in mask:
+            self.assertIsInstance(cpu, int)
+            self.assertGreaterEqual(cpu, 0)
+            self.assertLess(cpu, 1 << 32)
 
     @requires_sched_affinity
-    @support.cpython_only
-    def test_cpu_set_sizeof(self):
-        self.assertGreater(sys.getsizeof(posix.cpu_set(1000)),
-                           sys.getsizeof(posix.cpu_set(1)))
+    def test_sched_setaffinity(self):
+        mask = posix.sched_getaffinity(0)
+        if len(mask) > 1:
+            # Empty masks are forbidden
+            mask.pop()
+        posix.sched_setaffinity(0, mask)
+        self.assertEqual(posix.sched_getaffinity(0), mask)
+        self.assertRaises(OSError, posix.sched_setaffinity, 0, [])
+        self.assertRaises(ValueError, posix.sched_setaffinity, 0, [-10])
+        self.assertRaises(OverflowError, posix.sched_setaffinity, 0, [1<<128])
+        self.assertRaises(OSError, posix.sched_setaffinity, -1, mask)
 
     def test_rtld_constants(self):
         # check presence of major RTLD_* constants

Misc/NEWS

@@ -77,6 +77,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #12655: Instead of requiring a custom type, os.sched_getaffinity and
+  os.sched_setaffinity now use regular sets of integers to represent the CPUs
+  a process is restricted to.
+
 - Issue #15538: Fix compilation of the getnameinfo() / getaddrinfo()
   emulation code.  Patch by Philipp Hagemeister.