add test for memory leakage during deletion of value

Author: Vizonex

requirements/pytest.txt

@@ -2,3 +2,4 @@ objgraph==3.6.2
 pytest==8.4.0
 pytest-codspeed==3.2.0
 pytest-cov==6.1.0
+psutil==7.0.0

tests/isolated/multidict_pop.py

@@ -0,0 +1,39 @@
+# Test for memory leaks surrounding deletion of values.
+# SEE: https://github.com/aio-libs/multidict/issues/1232
+
+import gc
+import sys
+import psutil
+import os
+from multidict import MultiDict
+
+def get_memory_usage():
+    process = psutil.Process(os.getpid())
+    memory_info = process.memory_info()
+    return memory_info.rss / (1024 * 1024)
+
+keys = [f"X-Any-{i}" for i in range(1000)]
+headers = {key: key * 2 for key in keys}
+
+
+def _run_isolated_case() -> None:
+    for _ in range(10):
+        for _ in range(1000):
+            result = MultiDict()
+            result.update(headers)
+            for k in keys:
+                result.pop(k)
+                # popitem() currently is unaffected but the others all have memory leaks...
+                # result.popone(k)
+                # result.popall(k)
+            del result
+        gc.collect()
+        usage = get_memory_usage()
+        # We should never go over 100MB
+        if usage > 100:
+            sys.exit(1)
+    sys.exit(0)
+
+if __name__ == "__main__":
+    _run_isolated_case()
+

tests/test_leaks.py

@@ -15,6 +15,7 @@
         "multidict_extend_multidict.py",
         "multidict_extend_tuple.py",
         "multidict_update_multidict.py",
+        "multidict_pop.py"
     ),
 )
 @pytest.mark.leaks