Issue #18214: Improve finalization of Python modules to avoid setting their globals to None, in most cases.
diff --git a/Lib/rlcompleter.py b/Lib/rlcompleter.py
index d3a4437..8775730 100644
--- a/Lib/rlcompleter.py
+++ b/Lib/rlcompleter.py
@@ -29,6 +29,7 @@
"""
+import atexit
import builtins
import __main__
@@ -158,3 +159,8 @@
pass
else:
readline.set_completer(Completer().complete)
+ # Release references early at shutdown (the readline module's
+ # contents are quasi-immortal, and the completer function holds a
+ # reference to globals).
+ atexit.register(lambda: readline.set_completer(None))
+
diff --git a/Lib/site.py b/Lib/site.py
index 96a4bef..08b98eb 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -68,6 +68,7 @@
ImportError exception, it is silently ignored.
"""
+import atexit
import sys
import os
import re
@@ -86,6 +87,25 @@
USER_BASE = None
+_no_builtin = object()
+
+def _patch_builtins(**items):
+ # When patching builtins, we make some objects almost immortal
+ # (builtins are only reclaimed at the very end of the interpreter
+ # shutdown sequence). To avoid keeping to many references alive,
+ # we register callbacks to undo our builtins additions.
+ old_items = {k: getattr(builtins, k, _no_builtin) for k in items}
+ def unpatch(old_items=old_items):
+ for k, v in old_items.items():
+ if v is _no_builtin:
+ delattr(builtins, k)
+ else:
+ setattr(builtins, k, v)
+ for k, v in items.items():
+ setattr(builtins, k, v)
+ atexit.register(unpatch)
+
+
def makepath(*paths):
dir = os.path.join(*paths)
try:
@@ -357,8 +377,7 @@
except:
pass
raise SystemExit(code)
- builtins.quit = Quitter('quit')
- builtins.exit = Quitter('exit')
+ _patch_builtins(quit=Quitter('quit'), exit=Quitter('exit'))
class _Printer(object):
@@ -423,20 +442,20 @@
def setcopyright():
"""Set 'copyright' and 'credits' in builtins"""
- builtins.copyright = _Printer("copyright", sys.copyright)
+ _patch_builtins(copyright=_Printer("copyright", sys.copyright))
if sys.platform[:4] == 'java':
- builtins.credits = _Printer(
+ _patch_builtins(credits=_Printer(
"credits",
- "Jython is maintained by the Jython developers (www.jython.org).")
+ "Jython is maintained by the Jython developers (www.jython.org)."))
else:
- builtins.credits = _Printer("credits", """\
+ _patch_builtins(credits=_Printer("credits", """\
Thanks to CWI, CNRI, BeOpen.com, Zope Corporation and a cast of thousands
- for supporting Python development. See www.python.org for more information.""")
+ for supporting Python development. See www.python.org for more information."""))
here = os.path.dirname(os.__file__)
- builtins.license = _Printer(
+ _patch_builtins(license=_Printer(
"license", "See http://www.python.org/%.3s/license.html" % sys.version,
["LICENSE.txt", "LICENSE"],
- [os.path.join(here, os.pardir), here, os.curdir])
+ [os.path.join(here, os.pardir), here, os.curdir]))
class _Helper(object):
@@ -453,7 +472,7 @@
return pydoc.help(*args, **kwds)
def sethelper():
- builtins.help = _Helper()
+ _patch_builtins(help=_Helper())
def enablerlcompleter():
"""Enable default readline configuration on interactive prompts, by
diff --git a/Lib/test/final_a.py b/Lib/test/final_a.py
new file mode 100644
index 0000000..390ee88
--- /dev/null
+++ b/Lib/test/final_a.py
@@ -0,0 +1,19 @@
+"""
+Fodder for module finalization tests in test_module.
+"""
+
+import shutil
+import test.final_b
+
+x = 'a'
+
+class C:
+ def __del__(self):
+ # Inspect module globals and builtins
+ print("x =", x)
+ print("final_b.x =", test.final_b.x)
+ print("shutil.rmtree =", getattr(shutil.rmtree, '__name__', None))
+ print("len =", getattr(len, '__name__', None))
+
+c = C()
+_underscored = C()
diff --git a/Lib/test/final_b.py b/Lib/test/final_b.py
new file mode 100644
index 0000000..7228d82
--- /dev/null
+++ b/Lib/test/final_b.py
@@ -0,0 +1,19 @@
+"""
+Fodder for module finalization tests in test_module.
+"""
+
+import shutil
+import test.final_a
+
+x = 'b'
+
+class C:
+ def __del__(self):
+ # Inspect module globals and builtins
+ print("x =", x)
+ print("final_a.x =", test.final_a.x)
+ print("shutil.rmtree =", getattr(shutil.rmtree, '__name__', None))
+ print("len =", getattr(len, '__name__', None))
+
+c = C()
+_underscored = C()
diff --git a/Lib/test/test_module.py b/Lib/test/test_module.py
index b34b30f..3000cec 100644
--- a/Lib/test/test_module.py
+++ b/Lib/test/test_module.py
@@ -1,6 +1,7 @@
# Test the module type
import unittest
from test.support import run_unittest, gc_collect
+from test.script_helper import assert_python_ok
import sys
ModuleType = type(sys)
@@ -70,7 +71,6 @@
"__loader__": None, "__package__": None})
self.assertTrue(foo.__dict__ is d)
- @unittest.expectedFailure
def test_dont_clear_dict(self):
# See issue 7140.
def f():
@@ -181,6 +181,19 @@
self.assertEqual(r[:25], "<module 'unittest' from '")
self.assertEqual(r[-13:], "__init__.py'>")
+ 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")
+ self.assertFalse(err)
+ lines = out.splitlines()
+ self.assertEqual(set(lines), {
+ b"x = a",
+ b"x = b",
+ b"final_a.x = a",
+ b"final_b.x = b",
+ b"len = len",
+ b"shutil.rmtree = rmtree"})
+
# frozen and namespace module reprs are tested in importlib.
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 3f093e6..26c7ae7 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -810,7 +810,7 @@
# memoryview
check(memoryview(b''), size('Pnin 2P2n2i5P 3cPn'))
# module
- check(unittest, size('PnP'))
+ check(unittest, size('PnPPP'))
# None
check(None, size(''))
# NotImplementedType