diff --git a/Include/internal/pycore_pymem.h b/Include/internal/pycore_pymem.h
index 02537bdfef8598..3e12084b82ab26 100644
--- a/Include/internal/pycore_pymem.h
+++ b/Include/internal/pycore_pymem.h
@@ -88,7 +88,7 @@ extern wchar_t *_PyMem_DefaultRawWcsdup(const wchar_t *str);
extern int _PyMem_DebugEnabled(void);
// Enqueue a pointer to be freed possibly after some delay.
-extern void _PyMem_FreeDelayed(void *ptr);
+extern void _PyMem_FreeDelayed(void *ptr, size_t size);
// Enqueue an object to be freed possibly after some delay
#ifdef Py_GIL_DISABLED
diff --git a/Include/internal/pycore_qsbr.h b/Include/internal/pycore_qsbr.h
index b835c3abaf5d0b..e839427ddf45db 100644
--- a/Include/internal/pycore_qsbr.h
+++ b/Include/internal/pycore_qsbr.h
@@ -51,6 +51,10 @@ struct _qsbr_thread_state {
// Used to defer advancing write sequence a fixed number of times
int deferrals;
+ // Estimate for the amount of memory that is held by this thread since
+ // the last non-deferred advance.
+ size_t memory_deferred;
+
// Is this thread state allocated?
bool allocated;
struct _qsbr_thread_state *freelist_next;
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-06-03-21-06-22.gh-issue-133136.Usnvri.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-03-21-06-22.gh-issue-133136.Usnvri.rst
new file mode 100644
index 00000000000000..a9501c13c95b3a
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-03-21-06-22.gh-issue-133136.Usnvri.rst
@@ -0,0 +1,2 @@
+Limit excess memory usage in the :term:`free threading` build when a
+large dictionary or list is resized and accessed by multiple threads.
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index ee869d991d93cd..d0ce49d9d14ef6 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -3350,7 +3350,7 @@ create_tlbc_lock_held(PyCodeObject *co, Py_ssize_t idx)
}
memcpy(new_tlbc->entries, tlbc->entries, tlbc->size * sizeof(void *));
_Py_atomic_store_ptr_release(&co->co_tlbc, new_tlbc);
- _PyMem_FreeDelayed(tlbc);
+ _PyMem_FreeDelayed(tlbc, tlbc->size * sizeof(void *));
tlbc = new_tlbc;
}
char *bc = PyMem_Calloc(1, _PyCode_NBYTES(co));
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index fd8ccf56324207..6ff97cd67111a4 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -813,7 +813,7 @@ free_keys_object(PyDictKeysObject *keys, bool use_qsbr)
{
#ifdef Py_GIL_DISABLED
if (use_qsbr) {
- _PyMem_FreeDelayed(keys);
+ _PyMem_FreeDelayed(keys, _PyDict_KeysSize(keys));
return;
}
#endif
@@ -858,7 +858,7 @@ free_values(PyDictValues *values, bool use_qsbr)
assert(values->embedded == 0);
#ifdef Py_GIL_DISABLED
if (use_qsbr) {
- _PyMem_FreeDelayed(values);
+ _PyMem_FreeDelayed(values, values_size_from_count(values->capacity));
return;
}
#endif
diff --git a/Objects/listobject.c b/Objects/listobject.c
index c5895645a2dd12..23d3472b6d4153 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -61,7 +61,8 @@ free_list_items(PyObject** items, bool use_qsbr)
#ifdef Py_GIL_DISABLED
_PyListArray *array = _Py_CONTAINER_OF(items, _PyListArray, ob_item);
if (use_qsbr) {
- _PyMem_FreeDelayed(array);
+ size_t size = sizeof(_PyListArray) + array->allocated * sizeof(PyObject *);
+ _PyMem_FreeDelayed(array, size);
}
else {
PyMem_Free(array);
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index d3931aab623b70..5af2ed5a21afa9 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -1141,8 +1141,29 @@ free_work_item(uintptr_t ptr, delayed_dealloc_cb cb, void *state)
}
}
+#ifdef Py_GIL_DISABLED
+static int
+should_advance_qsbr(_PyThreadStateImpl *tstate, size_t size)
+{
+ // If the deferred memory exceeds 1 MiB, we force an advance in the
+ // shared QSBR sequence number to limit excess memory usage.
+ static const size_t QSBR_DEFERRED_LIMIT = 1024 * 1024;
+ if (size > QSBR_DEFERRED_LIMIT) {
+ tstate->qsbr->memory_deferred = 0;
+ return 1;
+ }
+
+ tstate->qsbr->memory_deferred += size;
+ if (tstate->qsbr->memory_deferred > QSBR_DEFERRED_LIMIT) {
+ tstate->qsbr->memory_deferred = 0;
+ return 1;
+ }
+ return 0;
+}
+#endif
+
static void
-free_delayed(uintptr_t ptr)
+free_delayed(uintptr_t ptr, size_t size)
{
#ifndef Py_GIL_DISABLED
free_work_item(ptr, NULL, NULL);
@@ -1200,23 +1221,29 @@ free_delayed(uintptr_t ptr)
}
assert(buf != NULL && buf->wr_idx < WORK_ITEMS_PER_CHUNK);
- uint64_t seq = _Py_qsbr_deferred_advance(tstate->qsbr);
+ uint64_t seq;
+ int force_advance = should_advance_qsbr(tstate, size);
+ if (force_advance) {
+ seq = _Py_qsbr_advance(tstate->qsbr->shared);
+ }
+ else {
+ seq = _Py_qsbr_deferred_advance(tstate->qsbr);
+ }
buf->array[buf->wr_idx].ptr = ptr;
buf->array[buf->wr_idx].qsbr_goal = seq;
buf->wr_idx++;
-
- if (buf->wr_idx == WORK_ITEMS_PER_CHUNK) {
+ if (buf->wr_idx == WORK_ITEMS_PER_CHUNK || force_advance) {
_PyMem_ProcessDelayed((PyThreadState *)tstate);
}
#endif
}
void
-_PyMem_FreeDelayed(void *ptr)
+_PyMem_FreeDelayed(void *ptr, size_t size)
{
assert(!((uintptr_t)ptr & 0x01));
if (ptr != NULL) {
- free_delayed((uintptr_t)ptr);
+ free_delayed((uintptr_t)ptr, size);
}
}
@@ -1226,7 +1253,7 @@ _PyObject_XDecRefDelayed(PyObject *ptr)
{
assert(!((uintptr_t)ptr & 0x01));
if (ptr != NULL) {
- free_delayed(((uintptr_t)ptr)|0x01);
+ free_delayed(((uintptr_t)ptr)|0x01, 64);
}
}
#endif
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