5 files changed, 71 insertions, 17 deletions

diff --git a/Python/gc.c b/Python/gc.c
index f47c74f..9f9a755 100644
--- a/Python/gc.c
+++ b/Python/gc.c
@@ -1019,21 +1019,6 @@ delete_garbage(PyThreadState *tstate, GCState *gcstate,
     }
 }
 
-/* Clear all free lists
- * All free lists are cleared during the collection of the highest generation.
- * Allocated items in the free list may keep a pymalloc arena occupied.
- * Clearing the free lists may give back memory to the OS earlier.
- */
-static void
-clear_freelists(PyInterpreterState *interp)
-{
-    _PyTuple_ClearFreeList(interp);
-    _PyFloat_ClearFreeList(interp);
-    _PyList_ClearFreeList(interp);
-    _PyDict_ClearFreeList(interp);
-    _PyAsyncGen_ClearFreeLists(interp);
-    _PyContext_ClearFreeList(interp);
-}
 
 // Show stats for objects in each generations
 static void
@@ -1449,7 +1434,7 @@ gc_collect_main(PyThreadState *tstate, int generation, _PyGC_Reason reason)
     /* Clear free list only during the collection of the highest
      * generation */
     if (generation == NUM_GENERATIONS-1) {
-        clear_freelists(tstate->interp);
+        _PyGC_ClearAllFreeLists(tstate->interp);
     }
 
     if (_PyErr_Occurred(tstate)) {
diff --git a/Python/gc_free_threading.c b/Python/gc_free_threading.c
new file mode 100644
index 0000000..aea2728
--- /dev/null
+++ b/Python/gc_free_threading.c
@@ -0,0 +1,32 @@
+#include "Python.h"
+#include "pycore_pystate.h"   // _PyFreeListState_GET()
+#include "pycore_tstate.h"    // _PyThreadStateImpl
+
+#ifdef Py_GIL_DISABLED
+
+/* Clear all free lists
+ * All free lists are cleared during the collection of the highest generation.
+ * Allocated items in the free list may keep a pymalloc arena occupied.
+ * Clearing the free lists may give back memory to the OS earlier.
+ * Free-threading version: Since freelists are managed per thread,
+ * GC should clear all freelists by traversing all threads.
+ */
+void
+_PyGC_ClearAllFreeLists(PyInterpreterState *interp)
+{
+    _PyTuple_ClearFreeList(interp);
+    _PyFloat_ClearFreeList(interp);
+    _PyDict_ClearFreeList(interp);
+    _PyAsyncGen_ClearFreeLists(interp);
+    _PyContext_ClearFreeList(interp);
+
+    HEAD_LOCK(&_PyRuntime);
+    _PyThreadStateImpl *tstate = (_PyThreadStateImpl *)interp->threads.head;
+    while (tstate != NULL) {
+        _Py_ClearFreeLists(&tstate->freelist_state, 0);
+        tstate = (_PyThreadStateImpl *)tstate->base.next;
+    }
+    HEAD_UNLOCK(&_PyRuntime);
+}
+
+#endif
diff --git a/Python/gc_gil.c b/Python/gc_gil.c
new file mode 100644
index 0000000..b0961cd
--- /dev/null
+++ b/Python/gc_gil.c
@@ -0,0 +1,23 @@
+#include "Python.h"
+#include "pycore_pystate.h"   // _Py_ClearFreeLists()
+
+#ifndef Py_GIL_DISABLED
+
+/* Clear all free lists
+ * All free lists are cleared during the collection of the highest generation.
+ * Allocated items in the free list may keep a pymalloc arena occupied.
+ * Clearing the free lists may give back memory to the OS earlier.
+ */
+void
+_PyGC_ClearAllFreeLists(PyInterpreterState *interp)
+{
+    _PyTuple_ClearFreeList(interp);
+    _PyFloat_ClearFreeList(interp);
+    _PyDict_ClearFreeList(interp);
+    _PyAsyncGen_ClearFreeLists(interp);
+    _PyContext_ClearFreeList(interp);
+
+    _Py_ClearFreeLists(&interp->freelist_state, 0);
+}
+
+#endif
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 1d8af26..bd6475f 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1752,13 +1752,16 @@ finalize_interp_types(PyInterpreterState *interp)
     _PyUnicode_ClearInterned(interp);
 
     _PyDict_Fini(interp);
-    _PyList_Fini(interp);
     _PyTuple_Fini(interp);
 
     _PySlice_Fini(interp);
 
     _PyUnicode_Fini(interp);
     _PyFloat_Fini(interp);
+
+    _PyFreeListState *state = _PyFreeListState_GET();
+    _PyList_Fini(state);
+
 #ifdef Py_DEBUG
     _PyStaticObjects_CheckRefcnt(interp);
 #endif
diff --git a/Python/pystate.c b/Python/pystate.c
index 21f16b7..ddd57f7 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -1456,6 +1456,12 @@ clear_datastack(PyThreadState *tstate)
 }
 
 void
+_Py_ClearFreeLists(_PyFreeListState *state, int is_finalization)
+{
+    _PyList_ClearFreeList(state, is_finalization);
+}
+
+void
 PyThreadState_Clear(PyThreadState *tstate)
 {
     assert(tstate->_status.initialized && !tstate->_status.cleared);
@@ -1537,6 +1543,11 @@ PyThreadState_Clear(PyThreadState *tstate)
         // don't call _PyInterpreterState_SetNotRunningMain() yet.
         tstate->on_delete(tstate->on_delete_data);
     }
+#ifdef Py_GIL_DISABLED
+    // Each thread should clear own freelists in free-threading builds.
+    _PyFreeListState *freelist_state = &((_PyThreadStateImpl*)tstate)->freelist_state;
+    _Py_ClearFreeLists(freelist_state, 0);
+#endif
 
     _PyThreadState_ClearMimallocHeaps(tstate);