Use support.gc_collect in test_descr + heap dump on support.gc_collect failure

Author: steve-s

ci/AGENTS.md

@@ -16,3 +16,4 @@ Jsonnet/libsonnet CI definitions consumed by GitHub Actions matrix generation.
 ## ANTI-PATTERNS
 - Don’t encode secrets or environment-specific paths here.
 - Keep changes compatible with matrix generation (small diffs, deterministic output).
+- NEVER edit CI files in `./graal`

ci/python-gate.libsonnet

@@ -408,6 +408,10 @@
         python_version: "3.8",
         targets: [self.target],
         logs+: $.logs(self.os, self.arch),
+        catch_files+: [
+            // generated by patch in CPython test support
+            "HEAP DUMP: (?P<filename>.+\\.hprof)",
+        ],
         // all gates share the same base set of downloads
         downloads+: $.downloads(self.os, self.arch),
         // all gates share the same base environment

graalpython/lib-python/3/test/support/__init__.py

@@ -793,6 +793,9 @@ def gc_collect(until = None):
             i += 1
             if i > 1000:
                 print("WARNING: timeout while waiting for GC")
+                if is_graalpy and hasattr(__graalpython__, 'dump_heap'):
+                    dump_path = __graalpython__.dump_heap()
+                    print(f"HEAP DUMP: {dump_path}")
                 break
 
 @contextlib.contextmanager

graalpython/lib-python/3/test/test_descr.py

@@ -5016,7 +5016,7 @@ class Child(Parent):
         self.assertEqual(Parent.__subclasses__(), [Child])
 
         del Child
-        gc.collect()
+        support.gc_collect(lambda: len(Parent.__subclasses__()) > 0)
         self.assertEqual(Parent.__subclasses__(), [])
 
     def test_attr_raise_through_property(self):