8000 gh-118527: Intern code consts in free-threaded build (#118667) · python/cpython@723d4d2 · GitHub < 8000 meta property="og:updated_time" content="1715040759" />
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gh-118527: Intern code consts in free-threaded build (#118667)
We already intern and immortalize most string constants. In the free-threaded build, other constants can be a source of reference count contention because they are shared by all threads running the same code objects.
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14 files changed

+375
-18
lines changed

14 files changed

+375
-18
lines changed

‎Include/internal/pycore_code.h

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Original file line numberDiff line numberDiff line change
@@ -8,6 +8,8 @@ extern "C" {
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#include "pycore_lock.h" // PyMutex
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// We hide some of the newer PyCodeObject fields behind macros.
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// This helps with backporting certain changes to 3.12.
@@ -16,6 +18,14 @@ extern "C" {
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#define _PyCode_HAS_INSTRUMENTATION(CODE) \
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(CODE->_co_instrumentation_version > 0)
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struct _py_code_state {
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PyMutex mutex;
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// Interned constants from code objects. Used by the free-threaded build.
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struct _Py_hashtable_t *constants;
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};
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extern PyStatus _PyCode_Init(PyInterpreterState *interp);
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extern void _PyCode_Fini(PyInterpreterState *interp);
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#define CODE_MAX_WATCHERS 8
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‎Include/internal/pycore_interp.h

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@@ -245,6 +245,7 @@ struct _is {
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struct _Py_long_state long_state;
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struct _dtoa_state dtoa;
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struct _py_func_state func_state;
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struct _py_code_state code_state;
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struct _Py_dict_state dict_state;
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struct _Py_exc_state exc_state;

‎Include/internal/pycore_setobject.h

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Original file line numberDiff line numberDiff line change
@@ -30,6 +30,9 @@ PyAPI_DATA(PyObject *) _PySet_Dummy;
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PyAPI_FUNC(int) _PySet_Contains(PySetObject *so, PyObject *key);
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// Clears the set without acquiring locks. Used by _PyCode_Fini.
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extern void _PySet_ClearInternal(PySetObject *so);
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#ifdef __cplusplus
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}
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#endif

‎Lib/test/support/__init__.py

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Original file line numberDiff line numberDiff line change
@@ -535,6 +535,15 @@ def suppress_immortalization(suppress=True):
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finally:
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_testinternalcapi.set_immortalize_deferred(*old_values)
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538+
def skip_if_suppress_immortalization():
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try:
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import _testinternalcapi
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except ImportError:
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return
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return unittest.skipUnless(_testinternalcapi.get_immortalize_deferred(),
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"requires immortalization of deferred objects")
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MS_WINDOWS = (sys.platform == 'win32')
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# Is not actually used in tests, but is kept for compatibility.

‎Lib/test/test_code.py

Lines changed: 22 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -142,7 +142,8 @@
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from test.support import (cpython_only,
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check_impl_detail, requires_debug_ranges,
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gc_collect, Py_GIL_DISABLED,
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suppress_immortalization)
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suppress_immortalization,
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skip_if_suppress_immortalization)
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from test.support.script_helper import assert_python_ok
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from test.support import threading_helper, import_helper
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from test.support.bytecode_helper import instructions_with_positions
@@ -570,11 +571,31 @@ def f(a='str_value'):
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self.assertIsInterned(f())
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@cpython_only
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@unittest.skipIf(Py_GIL_DISABLED, "free-threaded build interns all string constants")
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def test_interned_string_with_null(self):
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co = compile(r'res = "str\0value!"', '?', 'exec')
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v = self.find_const(co.co_consts, 'str\0value!')
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self.assertIsNotInterned(v)
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580+
@cpython_only
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@unittest.skipUnless(Py_GIL_DISABLED, "does not intern all constants")
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@skip_if_suppress_immortalization()
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def test_interned_constants(self):
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# compile separately to avoid compile time de-duping
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globals = {}
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exec(textwrap.dedent("""
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def func1():
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return (0.0, (1, 2, "hello"))
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"""), globals)
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exec(textwrap.dedent("""
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def func2():
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return (0.0, (1, 2, "hello"))
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"""), globals)
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self.assertTrue(globals["func1"]() is globals["func2"]())
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class CodeWeakRefTest(unittest.TestCase):
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‎Lib/test/test_ctypes/test_internals.py

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Original file line numberDiff line numberDiff line change
@@ -28,7 +28,7 @@ def test_ints(self):
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self.assertEqual(ci._objects, None)
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def test_c_char_p(self):
31-
s = b"Hello, World"
31+
s = "Hello, World".encode("ascii")
3232
refcnt = sys.getrefcount(s)
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cs = c_char_p(s)
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self.assertEqual(refcnt + 1, sys.getrefcount(s))

‎Lib/test/test_ctypes/test_python_api.py

Lines changed: 1 addition & 1 deletion
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@@ -47,7 +47,7 @@ def test_PyLong_Long(self):
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4848
@support.refcount_test
4949
def test_PyObj_FromPtr(self):
50-
s = "abc def ghi jkl"
50+
s = object()
5151
ref = sys.getrefcount(s)
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# id(python-object) is the address
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pyobj = _ctypes.PyObj_FromPtr(id(s))

‎Lib/test/test_memoryio.py

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@@ -801,7 +801,7 @@ def test_sizeof(self):
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802802
def _test_cow_mutation(self, mutation):
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# Common code for all BytesIO copy-on-write mutation tests.
804-
imm = b' ' * 1024
804+
imm = (' ' * 1024).encode("ascii")
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old_rc = sys.getrefcount(imm)
806806
memio = self.ioclass(imm)
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self.assertEqual(sys.getrefcount(imm), old_rc + 1)

‎Modules/_testinternalcapi.c

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Original file line numberDiff line numberDiff line change
@@ -1985,6 +1985,17 @@ set_immortalize_deferred(PyObject *self, PyObject *value)
19851985
#endif
19861986
}
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1988+
static PyObject *
1989+
get_immortalize_deferred(PyObject *self, PyObject *Py_UNUSED(ignored))
1990+
{
1991+
#ifdef Py_GIL_DISABLED
1992+
PyInterpreterState *interp = PyInterpreterState_Get();
1993+
return PyBool_FromLong(interp->gc.immortalize.enable_on_thread_created);
1994+
#else
1995+
Py_RETURN_FALSE;
1996+
#endif
1997+
}
1998+
19881999
static PyObject *
19892000
has_inline_values(PyObject *self, PyObject *obj)
19902001
{
@@ -2081,6 +2092,7 @@ static PyMethodDef module_functions[] = {
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{"py_thread_id", get_py_thread_id, METH_NOARGS},
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#endif
20832094
{"set_immortalize_deferred", set_immortalize_deferred, METH_VARARGS},
2095+
{"get_immortalize_deferred", get_immortalize_deferred, METH_NOARGS},
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#ifdef _Py_TIER2
20852097
{"uop_symbols_test", _Py_uop_symbols_test, METH_NOARGS},
20862098
#endif

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