gh-111968: Introduce _PyFreeListState and _PyFreeListState_GET API (gh-113584)

1 files changed, 32 insertions, 0 deletions

diff --git a/Python/gc_free_threading.c b/Python/gc_free_threading.c
new file mode 100644
index 00000000000..aea272840f9
--- /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