gh-139482: speed up os.environ.clear by 2x

Lib/os.py

@@ -742,6 +742,15 @@ def __repr__(self):
  )
  return f"environ({{{formatted_items}}})"
 
+ def clear(self):
+ while self._data:
+ for key in list(self._data):
+ unsetenv(key)
+ try:
+ del self._data[key]
+ except KeyError:
+ pass
+
  def copy(self):
  return dict(self)
 

Lib/test/test_os/test_os.py

@@ -1494,6 +1494,71 @@ def test_reload_environ(self):
  self.assertNotIn(b'test_env', os.environb)
  self.assertNotIn('test_env', os.environ)
 
+ def test_clear_empties_environ(self):
+ os.environ["test_key_to_clear1"] = "test_value_to_clear1"
+ os.environ["test_key_to_clear2"] = "test_value_to_clear2"
+ os.environ["test_key_to_clear3"] = "test_value_to_clear3"
+
+ # Test environ.clear() removes the environment variables
+ os.environ.clear()
+ self.assertEqual(os.environ, {})
+ if os.supports_bytes_environ:
+ self.assertEqual(os.environb, {})
+
+ # Repeated calls should be idempotent
+ os.environ.clear()
+ self.assertEqual(os.environ, {})
+ if os.supports_bytes_environ:
+ self.assertEqual(os.environb, {})
+
+ @unittest.skipUnless(os.supports_bytes_environ, "os.environb required for this test.")
+ def test_clear_empties_environb(self):
+ os.environb[b"test_key_to_clear1"] = b"test_value_to_clear1"
+ os.environb[b"test_key_to_clear2"] = b"test_value_to_clear2"
+ os.environb[b"test_key_to_clear3"] = b"test_value_to_clear3"
+
+ # Test environ.clear() removes the environment variables
+ os.environb.clear()
+ self.assertEqual(os.environ, {})
+ self.assertEqual(os.environb, {})
+
+ # Repeated calls should be idempotent
+ os.environb.clear()
+ self.assertEqual(os.environ, {})
+ self.assertEqual(os.environb, {})
+
+ def test_clear_empties_process_environment(self):
+ # Determine if on the current platform os.unsetenv()
+ # updates process environment.
+ os.environ['to_remove'] = 'value'
+ os.unsetenv('to_remove')
+ os.reload_environ()
+ if 'to_remove' in os.environ:
+ self.skipTest("os.unsetenv() doesn't update the process environment on this platform.")
+
+ # Set up two environment variables to be cleared
+ os.environ["test_env1"] = "some_value1"
+ os.environ["test_env2"] = "some_value2"
+
+ # Ensure the variables were persisted on process level.
+ os.reload_environ()
+ self.assertEqual(os.getenv("test_env1"), "some_value1")
+ self.assertEqual(os.getenv("test_env2"), "some_value2")
+
+ # Test that os.clear() clears both os.environ and os.environb
+ os.environ.clear()
+ self.assertEqual(os.environ, {})
+ if os.supports_bytes_environ:
+ self.assertEqual(os.environb, {})
+
+ # Test that os.clear() also clears the process environment,
+ # so that after os.reload_environ() environ and environb are still empty.
+ os.reload_environ()
+ self.assertEqual(os.environ, {})
+ if os.supports_bytes_environ:
+ self.assertEqual(os.environb, {})
+
+
 class WalkTests(unittest.TestCase):
  """Tests for os.walk()."""
  is_fwalk = False

Misc/NEWS.d/next/Library/2025-10-01-17-45-27.gh-issue-139482.yDMeEa.rst

@@ -0,0 +1,2 @@
+Ensure that :data:`os.environ.clear() <os.environ>`
+has linear complexity instead of quadratic complexity.