bpo-39489: Remove COUNT_ALLOCS special build (pythonGH-18259)

Remove:

* COUNT_ALLOCS macro
* sys.getcounts() function
* SHOW_ALLOC_COUNT code in listobject.c
* SHOW_TRACK_COUNT code in tupleobject.c
* PyConfig.show_alloc_count field
* -X showalloccount command line option
* @test.support.requires_type_collecting decorator

Author: vstinner

Doc/c-api/init_config.rst

@@ -627,14 +627,6 @@ PyConfig
 
       ``python3 -m MODULE`` argument. Used by :c:func:`Py_RunMain`.
 
-   .. c:member:: int show_alloc_count
-
-      Show allocation counts at exit?
-
-      Set to 1 by :option:`-X showalloccount <-X>` command line option.
-
-      Need a special Python build with ``COUNT_ALLOCS`` macro defined.
-
    .. c:member:: int show_ref_count
 
       Show total reference count at exit?
@@ -702,6 +694,10 @@ arguments are stripped from ``argv``: see :ref:`Command Line Arguments
 The ``xoptions`` options are parsed to set other options: see :option:`-X`
 option.
 
+.. versionchanged:: 3.9
+
+   The ``show_alloc_count`` field has been removed.
+
 
 Initialization with PyConfig
 ----------------------------

Doc/c-api/typeobj.rst

@@ -148,15 +148,6 @@ Quick Reference
    | :c:member:`~PyTypeObject.tp_vectorcall`        | :c:type:`vectorcallfunc`          |                   |   |   |   |   |
    +------------------------------------------------+-----------------------------------+-------------------+---+---+---+---+
 
-If :const:`COUNT_ALLOCS` is defined then the following (internal-only)
-fields exist as well:
-
-* :c:member:`~PyTypeObject.tp_allocs`
-* :c:member:`~PyTypeObject.tp_frees`
-* :c:member:`~PyTypeObject.tp_maxalloc`
-* :c:member:`~PyTypeObject.tp_prev`
-* :c:member:`~PyTypeObject.tp_next`
-
 .. [#slots]
    A slot name in parentheses indicates it is (effectively) deprecated.
    Names in angle brackets should be treated as read-only.
@@ -1904,31 +1895,6 @@ and :c:type:`PyType_Type` effectively act as defaults.)
    .. versionadded:: 3.9 (the field exists since 3.8 but it's only used since 3.9)
 
 
-The remaining fields are only defined if the feature test macro
-:const:`COUNT_ALLOCS` is defined, and are for internal use only. They are
-documented here for completeness.  None of these fields are inherited by
-subtypes.
-
-.. c:member:: Py_ssize_t PyTypeObject.tp_allocs
-
-   Number of allocations.
-
-.. c:member:: Py_ssize_t PyTypeObject.tp_frees
-
-   Number of frees.
-
-.. c:member:: Py_ssize_t PyTypeObject.tp_maxalloc
-
-   Maximum simultaneously allocated objects.
-
-.. c:member:: PyTypeObject* PyTypeObject.tp_prev
-
-   Pointer to the previous type object with a non-zero :c:member:`~PyTypeObject.tp_allocs` field.
-
-.. c:member:: PyTypeObject* PyTypeObject.tp_next
-
-   Pointer to the next type object with a non-zero :c:member:`~PyTypeObject.tp_allocs` field.
-
 Also, note that, in a garbage collected Python, :c:member:`~PyTypeObject.tp_dealloc` may be called from
 any Python thread, not just the thread which created the object (if the object
 becomes part of a refcount cycle, that cycle might be collected by a garbage

Doc/using/cmdline.rst

@@ -434,9 +434,6 @@ Miscellaneous options
      stored in a traceback of a trace. Use ``-X tracemalloc=NFRAME`` to start
      tracing with a traceback limit of *NFRAME* frames. See the
      :func:`tracemalloc.start` for more information.
-   * ``-X showalloccount`` to output the total count of allocated objects for
-     each type when the program finishes. This only works when Python was built with
-     ``COUNT_ALLOCS`` defined.
    * ``-X importtime`` to show how long each import takes. It shows module
      name, cumulative time (including nested imports) and self time (excluding
      nested imports).  Note that its output may be broken in multi-threaded
@@ -479,6 +476,8 @@ Miscellaneous options
       Using ``-X dev`` option, check *encoding* and *errors* arguments on
       string encoding and decoding operations.
 
+      The ``-X showalloccount`` option has been removed.
+
 
 Options you shouldn't use
 ~~~~~~~~~~~~~~~~~~~~~~~~~

Doc/whatsnew/3.9.rst

@@ -348,6 +348,9 @@ Build and C API Changes
   functions are now required to build Python.
   (Contributed by Victor Stinner in :issue:`39395`.)
 
+* The ``COUNT_ALLOCS`` special build macro has been removed.
+  (Contributed by Victor Stinner in :issue:`39489`.)
+
 
 Deprecated
 ==========
@@ -484,6 +487,12 @@ Removed
   ``asyncio.Condition`` and ``asyncio.Semaphore``.
   (Contributed by Andrew Svetlov in :issue:`34793`.)
 
+* The :func:`sys.getcounts` function, the ``-X showalloccount`` command line
+  option and the ``show_alloc_count`` field of the C structure
+  :c:type:`PyConfig` have been removed. They required a special Python build by
+  defining ``COUNT_ALLOCS`` macro.
+  (Contributed by Victor Stinner in :issue:`39489`.)
+
 
 Porting to Python 3.9
 =====================

Include/cpython/initconfig.h

@@ -153,7 +153,6 @@ typedef struct {
 
     int import_time;        /* PYTHONPROFILEIMPORTTIME, -X importtime */
     int show_ref_count;     /* -X showrefcount */
-    int show_alloc_count;   /* -X showalloccount */
     int dump_refs;          /* PYTHONDUMPREFS */
     int malloc_stats;       /* PYTHONMALLOCSTATS */
 

Include/cpython/object.h

@@ -255,15 +255,6 @@ typedef struct _typeobject {
 
     destructor tp_finalize;
     vectorcallfunc tp_vectorcall;
-
-#ifdef COUNT_ALLOCS
-    /* these must be last and never explicitly initialized */
-    Py_ssize_t tp_allocs;
-    Py_ssize_t tp_frees;
-    Py_ssize_t tp_maxalloc;
-    struct _typeobject *tp_prev;
-    struct _typeobject *tp_next;
-#endif
 } PyTypeObject;
 
 /* The *real* layout of a type object when allocated on the heap */
@@ -341,8 +332,6 @@ static inline void _Py_Dealloc_inline(PyObject *op)
     destructor dealloc = Py_TYPE(op)->tp_dealloc;
 #ifdef Py_TRACE_REFS
     _Py_ForgetReference(op);
-#else
-    _Py_INC_TPFREES(op);
 #endif
     (*dealloc)(op);
 }

Include/object.h

@@ -405,20 +405,6 @@ PyAPI_FUNC(void) _PyDebug_PrintTotalRefs(void);
 #define _Py_DEC_REFTOTAL
 #endif /* Py_REF_DEBUG */
 
-#ifdef COUNT_ALLOCS
-PyAPI_FUNC(void) _Py_inc_count(struct _typeobject *);
-PyAPI_FUNC(void) _Py_dec_count(struct _typeobject *);
-#define _Py_INC_TPALLOCS(OP)    _Py_inc_count(Py_TYPE(OP))
-#define _Py_INC_TPFREES(OP)     _Py_dec_count(Py_TYPE(OP))
-#define _Py_DEC_TPFREES(OP)     Py_TYPE(OP)->tp_frees--
-#define _Py_COUNT_ALLOCS_COMMA  ,
-#else
-#define _Py_INC_TPALLOCS(OP)
-#define _Py_INC_TPFREES(OP)
-#define _Py_DEC_TPFREES(OP)
-#define _Py_COUNT_ALLOCS_COMMA
-#endif /* COUNT_ALLOCS */
-
 /* Update the Python traceback of an object. This function must be called
    when a memory block is reused from a free list. */
 PyAPI_FUNC(int) _PyTraceMalloc_NewReference(PyObject *op);
@@ -438,15 +424,13 @@ static inline void _Py_NewReference(PyObject *op)
     if (_Py_tracemalloc_config.tracing) {
         _PyTraceMalloc_NewReference(op);
     }
-    _Py_INC_TPALLOCS(op);
     _Py_INC_REFTOTAL;
     Py_REFCNT(op) = 1;
 }
 
-static inline void _Py_ForgetReference(PyObject *op)
+static inline void _Py_ForgetReference(PyObject *Py_UNUSED(op))
 {
-    (void)op; /* may be unused, shut up -Wunused-parameter */
-    _Py_INC_TPFREES(op);
+    /* nothing to do */
 }
 #endif /* !Py_TRACE_REFS */
 

Lib/subprocess.py

@@ -325,7 +325,7 @@ def _args_from_interpreter_flags():
     if dev_mode:
         args.extend(('-X', 'dev'))
     for opt in ('faulthandler', 'tracemalloc', 'importtime',
-                'showalloccount', 'showrefcount', 'utf8'):
+                'showrefcount', 'utf8'):
         if opt in xoptions:
             value = xoptions[opt]
             if value is True:

Lib/test/support/__init__.py

@@ -2512,9 +2512,6 @@ def swap_item(obj, item, new_val):
             if item in obj:
                 del obj[item]
 
-requires_type_collecting = unittest.skipIf(hasattr(sys, 'getcounts'),
-                        'types are immortal if COUNT_ALLOCS is defined')
-
 def args_from_interpreter_flags():
     """Return a list of command-line arguments reproducing the current
     settings in sys.flags and sys.warnoptions."""

Lib/test/test_embed.py

@@ -356,7 +356,6 @@ class InitConfigTests(EmbeddingTestsMixin, unittest.TestCase):
         'tracemalloc': 0,
         'import_time': 0,
         'show_ref_count': 0,
-        'show_alloc_count': 0,
         'dump_refs': 0,
         'malloc_stats': 0,
 
@@ -729,7 +728,6 @@ def test_init_from_config(self):
             'tracemalloc': 2,
             'import_time': 1,
             'show_ref_count': 1,
-            'show_alloc_count': 1,
             'malloc_stats': 1,
 
             'stdio_encoding': 'iso8859-1',

Lib/test/test_gc.py

@@ -2,7 +2,7 @@
 import unittest.mock
 from test.support import (verbose, refcount_test, run_unittest,
                           cpython_only, start_threads,
-                          temp_dir, requires_type_collecting, TESTFN, unlink,
+                          temp_dir, TESTFN, unlink,
                           import_module)
 from test.support.script_helper import assert_python_ok, make_script
 
@@ -131,7 +131,6 @@ class A:
         del a
         self.assertNotEqual(gc.collect(), 0)
 
-    @requires_type_collecting
     def test_newinstance(self):
         class A(object):
             pass
@@ -709,7 +708,6 @@ def run_command(code):
         stderr = run_command(code % "gc.DEBUG_SAVEALL")
         self.assertNotIn(b"uncollectable objects at shutdown", stderr)
 
-    @requires_type_collecting
     def test_gc_main_module_at_shutdown(self):
         # Create a reference cycle through the __main__ module and check
         # it gets collected at interpreter shutdown.
@@ -723,7 +721,6 @@ def __del__(self):
         rc, out, err = assert_python_ok('-c', code)
         self.assertEqual(out.strip(), b'__del__ called')
 
-    @requires_type_collecting
     def test_gc_ordinary_module_at_shutdown(self):
         # Same as above, but with a non-__main__ module.
         with temp_dir() as script_dir:
@@ -743,7 +740,6 @@ def __del__(self):
             rc, out, err = assert_python_ok('-c', code)
             self.assertEqual(out.strip(), b'__del__ called')
 
-    @requires_type_collecting
     def test_global_del_SystemExit(self):
         code = """if 1:
             class ClassWithDel:

Lib/test/test_io.py

@@ -3492,7 +3492,6 @@ def __del__(self):
             """.format(iomod=iomod, kwargs=kwargs)
         return assert_python_ok("-c", code)
 
-    @support.requires_type_collecting
     def test_create_at_shutdown_without_encoding(self):
         rc, out, err = self._check_create_at_shutdown()
         if err:
@@ -3502,7 +3501,6 @@ def test_create_at_shutdown_without_encoding(self):
         else:
             self.assertEqual("ok", out.decode().strip())
 
-    @support.requires_type_collecting
     def test_create_at_shutdown_with_encoding(self):
         rc, out, err = self._check_create_at_shutdown(encoding='utf-8',
                                                       errors='strict')

Lib/test/test_logging.py

@@ -4252,7 +4252,6 @@ def __init__(self, name='MyLogger', level=logging.NOTSET):
             h.close()
             logging.setLoggerClass(logging.Logger)
 
-    @support.requires_type_collecting
     def test_logging_at_shutdown(self):
         # Issue #20037
         code = """if 1:

Lib/test/test_module.py

@@ -1,7 +1,7 @@
 # Test the module type
 import unittest
 import weakref
-from test.support import gc_collect, requires_type_collecting
+from test.support import gc_collect
 from test.support.script_helper import assert_python_ok
 
 import sys
@@ -101,7 +101,6 @@ def f():
         gc_collect()
         self.assertEqual(f().__dict__["bar"], 4)
 
-    @requires_type_collecting
     def test_clear_dict_in_ref_cycle(self):
         destroyed = []
         m = ModuleType("foo")
@@ -266,7 +265,6 @@ def test_module_repr_source(self):
         self.assertEqual(r[-len(ends_with):], ends_with,
                          '{!r} does not end with {!r}'.format(r, ends_with))
 
-    @requires_type_collecting
     def test_module_finalization_at_shutdown(self):
         # Module globals and builtins should still be available during shutdown
         rc, out, err = assert_python_ok("-c", "from test import final_a")

Lib/test/test_support.py

@@ -493,7 +493,6 @@ def test_args_from_interpreter_flags(self):
             ['-Wignore', '-X', 'dev'],
             ['-X', 'faulthandler'],
             ['-X', 'importtime'],
-            ['-X', 'showalloccount'],
             ['-X', 'showrefcount'],
             ['-X', 'tracemalloc'],
             ['-X', 'tracemalloc=3'],

Lib/test/test_sys.py

@@ -819,7 +819,6 @@ def test_getallocatedblocks(self):
         c = sys.getallocatedblocks()
         self.assertIn(c, range(b - 50, b + 50))
 
-    @test.support.requires_type_collecting
     def test_is_finalizing(self):
         self.assertIs(sys.is_finalizing(), False)
         # Don't use the atexit module because _Py_Finalizing is only set
@@ -841,7 +840,6 @@ def __del__(self):
         rc, stdout, stderr = assert_python_ok('-c', code)
         self.assertEqual(stdout.rstrip(), b'True')
 
-    @test.support.requires_type_collecting
     def test_issue20602(self):
         # sys.flags and sys.float_info were wiped during shutdown.
         code = """if 1:
@@ -1295,8 +1293,6 @@ def delx(self): del self.__x
         # type
         # static type: PyTypeObject
         fmt = 'P2nPI13Pl4Pn9Pn11PIPP'
-        if hasattr(sys, 'getcounts'):
-            fmt += '3n2P'
         s = vsize(fmt)
         check(int, s)
         # class

Lib/test/test_threading.py

@@ -3,8 +3,7 @@
 """
 
 import test.support
-from test.support import (verbose, import_module, cpython_only,
-                          requires_type_collecting)
+from test.support import verbose, import_module, cpython_only
 from test.support.script_helper import assert_python_ok, assert_python_failure
 
 import random
@@ -552,7 +551,6 @@ def f():
         self.assertEqual(err, b"")
         self.assertEqual(data, "Thread-1\nTrue\nTrue\n")
 
-    @requires_type_collecting
     def test_main_thread_during_shutdown(self):
         # bpo-31516: current_thread() should still point to the main thread
         # at shutdown
@@ -1113,7 +1111,6 @@ def run():
         self.assertIn("ZeroDivisionError", err)
         self.assertNotIn("Unhandled exception", err)
 
-    @requires_type_collecting
     def test_print_exception_stderr_is_none_1(self):
         script = r"""if True:
             import sys

Lib/test/test_traceback.py

@@ -174,7 +174,6 @@ def do_test(firstlines, message, charset, lineno):
         # Issue #18960: coding spec should have no effect
         do_test("x=0\n# coding: GBK\n", "h\xe9 ho", 'utf-8', 5)
 
-    @support.requires_type_collecting
     def test_print_traceback_at_exit(self):
         # Issue #22599: Ensure that it is possible to use the traceback module
         # to display an exception at Python exit

Lib/test/test_warnings/__init__.py

@@ -1227,7 +1227,6 @@ def test_issue_8766(self):
 
 
 class FinalizationTest(unittest.TestCase):
-    @support.requires_type_collecting
     def test_finalization(self):
         # Issue #19421: warnings.warn() should not crash
         # during Python finalization

Lib/test/test_weakref.py

@@ -649,7 +649,6 @@ class D:
         del c1, c2, C, D
         gc.collect()
 
-    @support.requires_type_collecting
     def test_callback_in_cycle_resurrection(self):
         import gc
 

Misc/NEWS.d/next/Build/2020-01-29-19-17-02.bpo-39489.HKPzv-.rst

@@ -0,0 +1 @@
+Remove ``COUNT_ALLOCS`` special build.