Improve CPython's gc_collect to accept optional condition for repeated GC runs; update tests to use it

steve-s · steve-s · commit bed5ded12f40 · 2026-02-24T14:55:01.000+01:00
Update relevant tests to use this conditional form for more reliable collection
of weakly-referenced objects.
diff --git a/graalpython/lib-python/3/test/_test_multiprocessing.py b/graalpython/lib-python/3/test/_test_multiprocessing.py
@@ -5851,7 +5851,7 @@ def check_resource_tracker_death(self, signum, should_die):
             # ensure `sem` gets collected, which triggers communication with
             # the semaphore tracker
             del sem
-            gc_collect()
+            gc_collect(lambda: wr())
             self.assertIsNone(wr())
             if should_die:
                 self.assertEqual(len(all_warn), 1)
diff --git a/graalpython/lib-python/3/test/support/__init__.py b/graalpython/lib-python/3/test/support/__init__.py
@@ -769,7 +769,7 @@ def captured_stdin():
     return captured_output("stdin")
 
 
-def gc_collect():
+def gc_collect(until = None):
     """Force as many objects as possible to be collected.
 
     In non-CPython implementations of Python, this is needed because timely
@@ -784,9 +784,16 @@ def gc_collect():
     if is_graalpy:
         time.sleep(0.1)
     gc.collect()
-    if is_graalpy:
-        time.sleep(0.1)
-    gc.collect()
+    if until:
+        i = 0
+        while until():
+            if is_graalpy:
+                time.sleep(0.1)
+            gc.collect()
+            i += 1
+            if i > 1000:
+                print("WARNING: timeout while waiting for GC")
+                break
 
 @contextlib.contextmanager
 def disable_gc():
diff --git a/graalpython/lib-python/3/test/test_ast/test_ast.py b/graalpython/lib-python/3/test/test_ast/test_ast.py
@@ -92,7 +92,7 @@ class X:
         a.x.a = a
         ref = weakref.ref(a.x)
         del a
-        support.gc_collect()
+        support.gc_collect(lambda: ref())
         self.assertIsNone(ref())
 
     def test_snippets(self):
diff --git a/graalpython/lib-python/3/test/test_concurrent_futures/executor.py b/graalpython/lib-python/3/test/test_concurrent_futures/executor.py
@@ -106,5 +106,5 @@ def test_free_reference(self):
         for obj in self.executor.map(make_dummy_object, range(10)):
             wr = weakref.ref(obj)
             del obj
-            support.gc_collect()  # For PyPy or other GCs.
+            support.gc_collect(wr())  # For PyPy or other GCs.
             self.assertIsNone(wr())
diff --git a/graalpython/lib-python/3/test/test_concurrent_futures/test_as_completed.py b/graalpython/lib-python/3/test/test_concurrent_futures/test_as_completed.py
@@ -84,15 +84,15 @@ def test_free_reference_yielded_future(self):
                 futures_list.remove(future)
                 wr = weakref.ref(future)
                 del future
-                support.gc_collect()  # For PyPy or other GCs.
+                support.gc_collect(wr())  # For PyPy or other GCs.
                 self.assertIsNone(wr())
 
         futures_list[0].set_result("test")
         for future in futures.as_completed(futures_list):
             futures_list.remove(future)
             wr = weakref.ref(future)
             del future
-            support.gc_collect()  # For PyPy or other GCs.
+            support.gc_collect(wr())  # For PyPy or other GCs.
             self.assertIsNone(wr())
             if futures_list:
                 futures_list[0].set_result("test")
diff --git a/graalpython/lib-python/3/test/test_contextlib.py b/graalpython/lib-python/3/test/test_contextlib.py
@@ -342,7 +342,7 @@ def woohoo(a, b):
             a = weakref.ref(a)
             b = weakref.ref(b)
             # Allow test to work with a non-refcounted GC
-            support.gc_collect()
+            support.gc_collect(lambda: a() or b())
             self.assertIsNone(a())
             self.assertIsNone(b())
             yield
diff --git a/graalpython/lib-python/3/test/test_descr.py b/graalpython/lib-python/3/test/test_descr.py
@@ -4898,7 +4898,7 @@ def __init__(self):
         x.attr = 42
         wr = weakref.ref(x)
         del x
-        support.gc_collect()
+        support.gc_collect(lambda: wr())
         self.assertIsNone(wr())
         for o in gc.get_objects():
             self.assertIsNot(type(o), X)
diff --git a/graalpython/lib-python/3/test/test_functools.py b/graalpython/lib-python/3/test/test_functools.py
@@ -1872,7 +1872,7 @@ def test_staticmethod(x):
 
         del A
         del test_function
-        support.gc_collect()
+        support.gc_collect(lambda: any([ref() for ref in refs]))
 
         for ref in refs:
             self.assertIsNone(ref())
diff --git a/graalpython/lib-python/3/test/test_importlib/test_locks.py b/graalpython/lib-python/3/test/test_importlib/test_locks.py
@@ -136,7 +136,7 @@ def test_lock_lifetime(self):
         self.assertIn(name, self.bootstrap._module_locks)
         wr = weakref.ref(lock)
         del lock
-        support.gc_collect()
+        support.gc_collect(lambda: wr() or name in self.bootstrap._module_locks)
         self.assertNotIn(name, self.bootstrap._module_locks)
         self.assertIsNone(wr())
 
diff --git a/graalpython/lib-python/3/test/test_memoryview.py b/graalpython/lib-python/3/test/test_memoryview.py
@@ -17,6 +17,7 @@
 import struct
 
 from test.support import import_helper
+from test.support import gc_collect
 
 
 class MyObject:
@@ -688,7 +689,7 @@ def test_buffer_reference_loop(self):
         o.o = o
         wr = weakref.ref(o)
         del m, o
-        gc.collect()
+        gc_collect(lambda: wr())
         self.assertIsNone(wr())
 
     def test_picklebuffer_reference_loop(self):
@@ -698,7 +699,7 @@ def test_picklebuffer_reference_loop(self):
         o.o = o
         wr = weakref.ref(o)
         del pb, o
-        gc.collect()
+        gc_collect(lambda: wr())
         self.assertIsNone(wr())
 
 
diff --git a/graalpython/lib-python/3/test/test_unittest/test_assertions.py b/graalpython/lib-python/3/test/test_unittest/test_assertions.py
@@ -125,10 +125,10 @@ def test_with(self):
                     self.foo()
 
         Foo("test_functional").run()
-        gc_collect()  # For PyPy or other GCs.
+        gc_collect(lambda: wr())  # For PyPy or other GCs.
         self.assertIsNone(wr())
         Foo("test_with").run()
-        gc_collect()  # For PyPy or other GCs.
+        gc_collect(lambda: wr())  # For PyPy or other GCs.
         self.assertIsNone(wr())
 
     def testAssertNotRegex(self):
