From 0355bea8c6fa5ba392ec8a1c6cce51f2e3a8d32e Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 13 Jun 2022 16:52:03 +0200
Subject: [PATCH 1/3] gh-93353: Add test.support.late_deletion()
---
Lib/test/support/__init__.py | 35 +++++++++++++++++++++++++++++++++++
Lib/test/test_gc.py | 14 ++++----------
2 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 780d04b020da49..64be60a51c2184 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -2213,3 +2213,38 @@ def requires_venv_with_pip():
# True if Python is built with the Py_DEBUG macro defined: if
# Python is built in debug mode (./configure --with-pydebug).
Py_DEBUG = hasattr(sys, 'gettotalrefcount')
+
+
+def late_deletion(obj):
+ """
+ Keep a Python alive as long as possible.
+
+ Create a reference cycle and store the cycle in an object deleted late in
+ Python finalization. Try to keep the object alive until the very last
+ garbage collection.
+
+ The function keeps a strong reference by design. It should be called in a
+ subprocess to not mark a test as "leaking a reference".
+ """
+
+ # Late CPython finalization:
+ # - finalize_interp_clear()
+ # - _PyInterpreterState_Clear()
+ # - clear os.register_at_fork() callbacks
+ # - clear codecs.register() callbacks
+
+ ref_cycle = [obj]
+ ref_cycle.append(ref_cycle)
+
+ # PyInterpreterState.codec_search_path
+ import codecs
+ def search_func(encoding):
+ return None
+ search_func.reference = ref_cycle
+ codecs.register(search_func)
+
+ # PyInterpreterState.before_forkers
+ def atfork_func():
+ pass
+ atfork_func.reference = ref_cycle
+ os.register_at_fork(before=atfork_func)
diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index dbbd67b4fc88a1..087f72768fa4bf 100644
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -1440,19 +1440,13 @@ def test_ast_fini(self):
code = textwrap.dedent("""
import ast
import codecs
+ from test import support
# Small AST tree to keep their AST types alive
tree = ast.parse("def f(x, y): return 2*x-y")
- x = [tree]
- x.append(x)
-
- # Put the cycle somewhere to survive until the last GC collection.
- # Codec search functions are only cleared at the end of
- # interpreter_clear().
- def search_func(encoding):
- return None
- search_func.a = x
- codecs.register(search_func)
+
+ # Store the tree somewhere to survive until the last GC collection
+ support.late_deletion(tree)
""")
assert_python_ok("-c", code)
From 84eb078604fecda942a74482f83960bcb9c45f78 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 13 Jun 2022 20:05:47 +0200
Subject: [PATCH 2/3] Rephrase the documentation
---
Lib/test/support/__init__.py | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 64be60a51c2184..e0fdffe9d3bc98 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -2229,21 +2229,22 @@ def late_deletion(obj):
# Late CPython finalization:
# - finalize_interp_clear()
- # - _PyInterpreterState_Clear()
+ # - _PyInterpreterState_Clear(): Clear PyInterpreterState members
+ # (ex: codec_search_path, before_forkers)
# - clear os.register_at_fork() callbacks
# - clear codecs.register() callbacks
ref_cycle = [obj]
ref_cycle.append(ref_cycle)
- # PyInterpreterState.codec_search_path
+ # Store a reference in PyInterpreterState.codec_search_path
import codecs
def search_func(encoding):
return None
search_func.reference = ref_cycle
codecs.register(search_func)
- # PyInterpreterState.before_forkers
+ # Store a reference in PyInterpreterState.before_forkers
def atfork_func():
pass
atfork_func.reference = ref_cycle
From 148bcff880a11c3713778f11021cf0429c6ca40d Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 13 Jun 2022 21:54:49 +0200
Subject: [PATCH 3/3] Fix Windows support
---
Lib/test/support/__init__.py | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index e0fdffe9d3bc98..4baaeb766317f1 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -2244,8 +2244,9 @@ def search_func(encoding):
search_func.reference = ref_cycle
codecs.register(search_func)
- # Store a reference in PyInterpreterState.before_forkers
- def atfork_func():
- pass
- atfork_func.reference = ref_cycle
- os.register_at_fork(before=atfork_func)
+ if hasattr(os, 'register_at_fork'):
+ # Store a reference in PyInterpreterState.before_forkers
+ def atfork_func():
+ pass
+ atfork_func.reference = ref_cycle
+ os.register_at_fork(before=atfork_func)