bpo-31558: Add gc.freeze() (#3705)

Freeze all the objects tracked by gc - move them to a permanent generation
and ignore all the future collections. This can be used before a POSIX
fork() call to make the gc copy-on-write friendly or to speed up collection.

1 files changed, 6 insertions, 0 deletions

diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index 914efec3d3..904fc7d88c 100644
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -734,6 +734,12 @@ class GCTests(unittest.TestCase):
         self.assertEqual(new[1]["collections"], old[1]["collections"])
         self.assertEqual(new[2]["collections"], old[2]["collections"] + 1)
 
+    def test_freeze(self):
+        gc.freeze()
+        self.assertGreater(gc.get_freeze_count(), 0)
+        gc.unfreeze()
+        self.assertEqual(gc.get_freeze_count(), 0)
+
 
 class GCCallbackTests(unittest.TestCase):
     def setUp(self):