From dbc372c417b55670bbce82c649e108b2a2c63e5c Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Fri, 7 Feb 2025 15:28:44 +0100
Subject: [PATCH 01/13] Create freelist for small lists

---
 Include/internal/pycore_freelist_state.h |  3 +
 Objects/listobject.c                     | 95 ++++++++++++++++++------
 Objects/object.c                         |  5 ++
 3 files changed, 82 insertions(+), 21 deletions(-)

diff --git a/Include/internal/pycore_freelist_state.h b/Include/internal/pycore_freelist_state.h
index 46e2a82ea034560..b185a12ebf7cf71 100644
--- a/Include/internal/pycore_freelist_state.h
+++ b/Include/internal/pycore_freelist_state.h
@@ -10,6 +10,8 @@ extern "C" {
 
 #  define PyTuple_MAXSAVESIZE 20     // Largest tuple to save on freelist
 #  define Py_tuple_MAXFREELIST 2000  // Maximum number of tuples of each size to save
+#  define PyList_MAXSAVESIZE 10     // Largest list size  to save on freelist (minus one)
+#  define Py_small_lists_MAXFREELIST 40
 #  define Py_lists_MAXFREELIST 80
 #  define Py_list_iters_MAXFREELIST 10
 #  define Py_tuple_iters_MAXFREELIST 10
@@ -48,6 +50,7 @@ struct _Py_freelists {
     struct _Py_freelist complexes;
     struct _Py_freelist ints;
     struct _Py_freelist tuples[PyTuple_MAXSAVESIZE];
+    struct _Py_freelist small_lists[PyList_MAXSAVESIZE];
     struct _Py_freelist lists;
     struct _Py_freelist list_iters;
     struct _Py_freelist tuple_iters;
diff --git a/Objects/listobject.c b/Objects/listobject.c
index f9488cc5c384bab..2402c18e78d2e8e 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -258,6 +258,27 @@ _PyList_DebugMallocStats(FILE *out)
                            _PyType_PreHeaderSize(&PyList_Type) + sizeof(PyListObject));
 }
 
+
+static inline int
+maybe_small_list_freelist_push(PyObject *self)
+{
+    assert(PyList_CheckExact(self));
+    assert(0);
+
+    PyListObject *op = (PyListObject *)self;
+    PyObject **ob_item = _Py_atomic_load_ptr(&op->ob_item);
+
+
+    Py_ssize_t cap = op->allocated; // what is the difference between allocated and capacity in the FT build?
+
+    printf("maybe_small_list_freelist_push: cap %d\n", cap);
+    if (cap < PyList_MAXSAVESIZE) {
+        return _Py_FREELIST_PUSH(small_lists[cap], self, Py_small_lists_MAXFREELIST);
+    }
+    return 0;
+}
+
+
 PyObject *
 PyList_New(Py_ssize_t size)
 {
@@ -266,35 +287,49 @@ PyList_New(Py_ssize_t size)
         return NULL;
     }
 
-    PyListObject *op = _Py_FREELIST_POP(PyListObject, lists);
-    if (op == NULL) {
-        op = PyObject_GC_New(PyListObject, &PyList_Type);
-        if (op == NULL) {
-            return NULL;
-        }
+    PyListObject *op;
+
+    if (size < PyList_MAXSAVESIZE ) {
+        op = 0;
+        //op = (PyListObject *)_Py_FREELIST_POP(PyLongObject, small_lists[size]);
     }
-    if (size <= 0) {
-        op->ob_item = NULL;
+    if (op) {
+        // allocated with ob_item still allocated. we do need to set to zero?
+        if ( size>0) {
+        memset(&op->ob_item, 0, size * sizeof(PyObject *));
+        }
     }
     else {
-#ifdef Py_GIL_DISABLED
-        _PyListArray *array = list_allocate_array(size);
-        if (array == NULL) {
-            Py_DECREF(op);
-            return PyErr_NoMemory();
+        op = _Py_FREELIST_POP(PyListObject, lists);
+        if (op == NULL) {
+            op = PyObject_GC_New(PyListObject, &PyList_Type);
+            if (op == NULL) {
+                return NULL;
+            }
         }
-        memset(&array->ob_item, 0, size * sizeof(PyObject *));
-        op->ob_item = array->ob_item;
+        if (size <= 0) {
+            op->ob_item = NULL;
+        }
+        else {
+#ifdef Py_GIL_DISABLED
+            _PyListArray *array = list_allocate_array(size);
+            if (array == NULL) {
+                Py_DECREF(op);
+                return PyErr_NoMemory();
+            }
+            memset(&array->ob_item, 0, size * sizeof(PyObject *));
+            op->ob_item = array->ob_item;
 #else
-        op->ob_item = (PyObject **) PyMem_Calloc(size, sizeof(PyObject *));
+            op->ob_item = (PyObject **) PyMem_Calloc(size, sizeof(PyObject *));
+            if (op->ob_item == NULL) {
+                Py_DECREF(op);
+                return PyErr_NoMemory();
+            }
 #endif
-        if (op->ob_item == NULL) {
-            Py_DECREF(op);
-            return PyErr_NoMemory();
         }
+        Py_SET_SIZE(op, size);
+        op->allocated = size;
     }
-    Py_SET_SIZE(op, size);
-    op->allocated = size;
     _PyObject_GC_TRACK(op);
     return (PyObject *) op;
 }
@@ -606,6 +641,18 @@ PyList_Append(PyObject *op, PyObject *newitem)
 
 /* Methods */
 
+void small_list_freelist_free(PyObject *self)
+{
+    assert(0);
+    printf("small_list_freelist_free\n");
+    assert(PyLong_CheckExact(self));
+    PyListObject *op = (PyListObject *)self;
+    if (op->ob_item != NULL) {
+        free_list_items(op->ob_item, false);
+    }
+    PyObject_GC_Del(op);
+}
+
 static void
 list_dealloc(PyObject *self)
 {
@@ -621,6 +668,12 @@ list_dealloc(PyObject *self)
         while (--i >= 0) {
             Py_XDECREF(op->ob_item[i]);
         }
+    }
+    if (0 && maybe_small_list_freelist_push(self) ) {
+        return;
+    }
+
+    if (op->ob_item != NULL) {
         free_list_items(op->ob_item, false);
         op->ob_item = NULL;
     }
diff --git a/Objects/object.c b/Objects/object.c
index f8206e5d3eca329..505025577ebc7b7 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -923,6 +923,8 @@ free_object(void *obj)
     Py_DECREF(tp);
 }
 
+extern void small_list_freelist_free(PyObject *);
+
 void
 _PyObject_ClearFreeLists(struct _Py_freelists *freelists, int is_finalization)
 {
@@ -933,6 +935,9 @@ _PyObject_ClearFreeLists(struct _Py_freelists *freelists, int is_finalization)
     for (Py_ssize_t i = 0; i < PyTuple_MAXSAVESIZE; i++) {
         clear_freelist(&freelists->tuples[i], is_finalization, free_object);
     }
+    for (Py_ssize_t i = 0; i < PyList_MAXSAVESIZE; i++) {
+        clear_freelist(&freelists->small_lists[i], is_finalization, small_list_freelist_free);
+    }
     clear_freelist(&freelists->lists, is_finalization, free_object);
     clear_freelist(&freelists->list_iters, is_finalization, free_object);
     clear_freelist(&freelists->tuple_iters, is_finalization, free_object);

From 0777dbae620d3a08d9e3604fd278cf6c2ac33f20 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Fri, 7 Feb 2025 21:19:51 +0100
Subject: [PATCH 02/13] working version

---
 Include/internal/pycore_freelist_state.h |  2 +-
 Objects/listobject.c                     | 53 +++++++++++++-----------
 Objects/object.c                         |  2 +-
 3 files changed, 30 insertions(+), 27 deletions(-)

diff --git a/Include/internal/pycore_freelist_state.h b/Include/internal/pycore_freelist_state.h
index b185a12ebf7cf71..9f8a0f4de687eb5 100644
--- a/Include/internal/pycore_freelist_state.h
+++ b/Include/internal/pycore_freelist_state.h
@@ -10,7 +10,7 @@ extern "C" {
 
 #  define PyTuple_MAXSAVESIZE 20     // Largest tuple to save on freelist
 #  define Py_tuple_MAXFREELIST 2000  // Maximum number of tuples of each size to save
-#  define PyList_MAXSAVESIZE 10     // Largest list size  to save on freelist (minus one)
+#  define PyList_MAXSAVESIZE 13     // Largest list size to save on freelist (minus one)
 #  define Py_small_lists_MAXFREELIST 40
 #  define Py_lists_MAXFREELIST 80
 #  define Py_list_iters_MAXFREELIST 10
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 2402c18e78d2e8e..d839b1aea3e7c6c 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -263,17 +263,14 @@ static inline int
 maybe_small_list_freelist_push(PyObject *self)
 {
     assert(PyList_CheckExact(self));
-    assert(0);
 
     PyListObject *op = (PyListObject *)self;
     PyObject **ob_item = _Py_atomic_load_ptr(&op->ob_item);
 
-
-    Py_ssize_t cap = op->allocated; // what is the difference between allocated and capacity in the FT build?
-
-    printf("maybe_small_list_freelist_push: cap %d\n", cap);
-    if (cap < PyList_MAXSAVESIZE) {
-        return _Py_FREELIST_PUSH(small_lists[cap], self, Py_small_lists_MAXFREELIST);
+    Py_ssize_t allocated = op->allocated;
+    if (allocated < PyList_MAXSAVESIZE) {
+        return _Py_FREELIST_PUSH(small_lists[allocated], self, Py_small_lists_MAXFREELIST);
+        //printf("maybe_small_list_freelist_push: allocated %d (mod %d), size %d, id %p\n", (int)allocated, op->allocated, (int)PyList_Size(self), (void *)self);
     }
     return 0;
 }
@@ -287,19 +284,23 @@ PyList_New(Py_ssize_t size)
         return NULL;
     }
 
-    PyListObject *op;
+    PyListObject *op=0;
 
-    if (size < PyList_MAXSAVESIZE ) {
-        op = 0;
-        //op = (PyListObject *)_Py_FREELIST_POP(PyLongObject, small_lists[size]);
-    }
-    if (op) {
-        // allocated with ob_item still allocated. we do need to set to zero?
-        if ( size>0) {
-        memset(&op->ob_item, 0, size * sizeof(PyObject *));
+    if (size < PyList_MAXSAVESIZE) {
+        op = (PyListObject *)_Py_FREELIST_POP(PyLongObject, small_lists[size]);
+        if (op) {
+            // allocated with ob_item still allocated, but we need to set the other fields
+            Py_SET_SIZE(op, size);
+            if ( size>0) {
+                memset(op->ob_item, 0, size * sizeof(PyObject *));
+            }
+            //printf("obtained list from small_lists[%d] (id %p, op->allocated %d, size %d, PyList_Size %d)\n", (int) size, op, (int)op->allocated, (int)size, (int)PyList_Size( (PyObject*)op));
+            assert (op->allocated >= size);
         }
+        op=0;
     }
-    else {
+    if (!op) {
+        // do we still need this freelist? if so, we could store it at small_lists[PyList_MAXSAVESIZE-1] with some special casing
         op = _Py_FREELIST_POP(PyListObject, lists);
         if (op == NULL) {
             op = PyObject_GC_New(PyListObject, &PyList_Type);
@@ -641,12 +642,13 @@ PyList_Append(PyObject *op, PyObject *newitem)
 
 /* Methods */
 
-void small_list_freelist_free(PyObject *self)
+void small_list_freelist_free(void *obj)
 {
-    assert(0);
-    printf("small_list_freelist_free\n");
-    assert(PyLong_CheckExact(self));
+    PyObject *self = (PyObject *)obj;
+
+    assert(PyList_CheckExact(self));
     PyListObject *op = (PyListObject *)self;
+    //printf("small_list_freelist_free: (op->allocated %d, size %d)\n",  (int)op->allocated, (int)PyList_Size(self));
     if (op->ob_item != NULL) {
         free_list_items(op->ob_item, false);
     }
@@ -669,16 +671,17 @@ list_dealloc(PyObject *self)
             Py_XDECREF(op->ob_item[i]);
         }
     }
-    if (0 && maybe_small_list_freelist_push(self) ) {
-        return;
+    if (PyList_CheckExact(op)) {
+        if( maybe_small_list_freelist_push(self) ) {
+            return;
+        }
     }
-
     if (op->ob_item != NULL) {
         free_list_items(op->ob_item, false);
         op->ob_item = NULL;
     }
     if (PyList_CheckExact(op)) {
-        _Py_FREELIST_FREE(lists, op, PyObject_GC_Del);
+       _Py_FREELIST_FREE(lists, op, PyObject_GC_Del);
     }
     else {
         PyObject_GC_Del(op);
diff --git a/Objects/object.c b/Objects/object.c
index 505025577ebc7b7..e74f3332cfcf4c6 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -923,7 +923,7 @@ free_object(void *obj)
     Py_DECREF(tp);
 }
 
-extern void small_list_freelist_free(PyObject *);
+extern void small_list_freelist_free(void *);
 
 void
 _PyObject_ClearFreeLists(struct _Py_freelists *freelists, int is_finalization)

From 814815a39eaff64f78705e2db37cf09b0f5ef3fe Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Sun, 9 Feb 2025 19:52:27 +0100
Subject: [PATCH 03/13] comments

---
 Objects/listobject.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index d839b1aea3e7c6c..04916b1f8e1f59d 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -262,11 +262,10 @@ _PyList_DebugMallocStats(FILE *out)
 static inline int
 maybe_small_list_freelist_push(PyObject *self)
 {
+    // todo: in the resizing there are some alignments on the allocation. can we use that here?
     assert(PyList_CheckExact(self));
 
     PyListObject *op = (PyListObject *)self;
-    PyObject **ob_item = _Py_atomic_load_ptr(&op->ob_item);
-
     Py_ssize_t allocated = op->allocated;
     if (allocated < PyList_MAXSAVESIZE) {
         return _Py_FREELIST_PUSH(small_lists[allocated], self, Py_small_lists_MAXFREELIST);
@@ -297,9 +296,9 @@ PyList_New(Py_ssize_t size)
             //printf("obtained list from small_lists[%d] (id %p, op->allocated %d, size %d, PyList_Size %d)\n", (int) size, op, (int)op->allocated, (int)size, (int)PyList_Size( (PyObject*)op));
             assert (op->allocated >= size);
         }
-        op=0;
+        //op=0;
     }
-    if (!op) {
+    if (op == NULL) {
         // do we still need this freelist? if so, we could store it at small_lists[PyList_MAXSAVESIZE-1] with some special casing
         op = _Py_FREELIST_POP(PyListObject, lists);
         if (op == NULL) {

From 6e5c67301307cf90287bcb4de2d035118c4b5096 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Sun, 9 Feb 2025 22:45:51 +0100
Subject: [PATCH 04/13] clear debugging code

---
 Objects/listobject.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 04916b1f8e1f59d..a2f945f21277f3e 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -269,7 +269,6 @@ maybe_small_list_freelist_push(PyObject *self)
     Py_ssize_t allocated = op->allocated;
     if (allocated < PyList_MAXSAVESIZE) {
         return _Py_FREELIST_PUSH(small_lists[allocated], self, Py_small_lists_MAXFREELIST);
-        //printf("maybe_small_list_freelist_push: allocated %d (mod %d), size %d, id %p\n", (int)allocated, op->allocated, (int)PyList_Size(self), (void *)self);
     }
     return 0;
 }
@@ -293,13 +292,12 @@ PyList_New(Py_ssize_t size)
             if ( size>0) {
                 memset(op->ob_item, 0, size * sizeof(PyObject *));
             }
-            //printf("obtained list from small_lists[%d] (id %p, op->allocated %d, size %d, PyList_Size %d)\n", (int) size, op, (int)op->allocated, (int)size, (int)PyList_Size( (PyObject*)op));
             assert (op->allocated >= size);
         }
         //op=0;
     }
     if (op == NULL) {
-        // do we still need this freelist? if so, we could store it at small_lists[PyList_MAXSAVESIZE-1] with some special casing
+        // do we still need this freelist? if so, we could store it at small_lists[0] with some special casing
         op = _Py_FREELIST_POP(PyListObject, lists);
         if (op == NULL) {
             op = PyObject_GC_New(PyListObject, &PyList_Type);
@@ -338,6 +336,15 @@ static PyObject *
 list_new_prealloc(Py_ssize_t size)
 {
     assert(size > 0);
+    if (size < PyList_MAXSAVESIZE) {
+        PyListObject *op = (PyListObject *)_Py_FREELIST_POP(PyLongObject, small_lists[size]);
+        if (op) {
+            // allocated with ob_item still allocated, but we need to set the other fields
+            assert (op->allocated >= size);
+            return op;
+        }
+    }
+
     PyListObject *op = (PyListObject *) PyList_New(0);
     if (op == NULL) {
         return NULL;
@@ -647,7 +654,6 @@ void small_list_freelist_free(void *obj)
 
     assert(PyList_CheckExact(self));
     PyListObject *op = (PyListObject *)self;
-    //printf("small_list_freelist_free: (op->allocated %d, size %d)\n",  (int)op->allocated, (int)PyList_Size(self));
     if (op->ob_item != NULL) {
         free_list_items(op->ob_item, false);
     }

From 258c72aad5e0e18896c855eca2a46a2575e0c715 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Mon, 10 Feb 2025 14:33:31 +0100
Subject: [PATCH 05/13] ci

---
 Objects/listobject.c | 7 +++++--
 Objects/object.c     | 4 ++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index a2f945f21277f3e..05ab7241df1468f 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -291,6 +291,9 @@ PyList_New(Py_ssize_t size)
             Py_SET_SIZE(op, size);
             if ( size>0) {
                 memset(op->ob_item, 0, size * sizeof(PyObject *));
+            } else {
+                // might be relatex later
+                op->ob_item = NULL;
             }
             assert (op->allocated >= size);
         }
@@ -341,7 +344,7 @@ list_new_prealloc(Py_ssize_t size)
         if (op) {
             // allocated with ob_item still allocated, but we need to set the other fields
             assert (op->allocated >= size);
-            return op;
+            return (PyObject *) op;
         }
     }
 
@@ -648,7 +651,7 @@ PyList_Append(PyObject *op, PyObject *newitem)
 
 /* Methods */
 
-void small_list_freelist_free(void *obj)
+void _Py_small_list_freelist_free(void *obj)
 {
     PyObject *self = (PyObject *)obj;
 
diff --git a/Objects/object.c b/Objects/object.c
index e74f3332cfcf4c6..1bfe44b9324bda6 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -923,7 +923,7 @@ free_object(void *obj)
     Py_DECREF(tp);
 }
 
-extern void small_list_freelist_free(void *);
+extern void _Py_small_list_freelist_free(void *);
 
 void
 _PyObject_ClearFreeLists(struct _Py_freelists *freelists, int is_finalization)
@@ -936,7 +936,7 @@ _PyObject_ClearFreeLists(struct _Py_freelists *freelists, int is_finalization)
         clear_freelist(&freelists->tuples[i], is_finalization, free_object);
     }
     for (Py_ssize_t i = 0; i < PyList_MAXSAVESIZE; i++) {
-        clear_freelist(&freelists->small_lists[i], is_finalization, small_list_freelist_free);
+        clear_freelist(&freelists->small_lists[i], is_finalization, _Py_small_list_freelist_free);
     }
     clear_freelist(&freelists->lists, is_finalization, free_object);
     clear_freelist(&freelists->list_iters, is_finalization, free_object);

From ef4052ae502ac88af90a3b952f3e7eb7bfd40b49 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Sun, 30 Mar 2025 20:56:16 +0200
Subject: [PATCH 06/13] fix test

---
 Lib/test/test_list.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index 260f9f4f607f152..9341727b970ef42 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -379,8 +379,9 @@ def test_no_memory(self):
         code = textwrap.dedent("""
         from test import support
         import sys
-        # Prime the freelist
-        l = [None]
+        # Prime the freelist, size needs to larger than the small list freelists
+        l = [None, None, None, None, None, None, None, None, None, None, None,
+             None, None, None, None, None, None, None, None, None,]
         del l
         support.inject_memory_error()
         l = [None]

From fb6b553fbcb36157bb751744e7debd84fba16a0a Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Thu, 3 Apr 2025 23:15:49 +0200
Subject: [PATCH 07/13] increase size used to that of the tuples

---
 Include/internal/pycore_freelist_state.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Include/internal/pycore_freelist_state.h b/Include/internal/pycore_freelist_state.h
index 9f8a0f4de687eb5..ce1d4da96fbc529 100644
--- a/Include/internal/pycore_freelist_state.h
+++ b/Include/internal/pycore_freelist_state.h
@@ -10,7 +10,7 @@ extern "C" {
 
 #  define PyTuple_MAXSAVESIZE 20     // Largest tuple to save on freelist
 #  define Py_tuple_MAXFREELIST 2000  // Maximum number of tuples of each size to save
-#  define PyList_MAXSAVESIZE 13     // Largest list size to save on freelist (minus one)
+#  define PyList_MAXSAVESIZE 21     // Largest list size to save on freelist (minus one)
 #  define Py_small_lists_MAXFREELIST 40
 #  define Py_lists_MAXFREELIST 80
 #  define Py_list_iters_MAXFREELIST 10

From be95b3d725ae1a46881e05830ba77cbd72d151f4 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Thu, 3 Apr 2025 23:21:21 +0200
Subject: [PATCH 08/13] revert size increase

---
 Include/internal/pycore_freelist_state.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Include/internal/pycore_freelist_state.h b/Include/internal/pycore_freelist_state.h
index ce1d4da96fbc529..9f8a0f4de687eb5 100644
--- a/Include/internal/pycore_freelist_state.h
+++ b/Include/internal/pycore_freelist_state.h
@@ -10,7 +10,7 @@ extern "C" {
 
 #  define PyTuple_MAXSAVESIZE 20     // Largest tuple to save on freelist
 #  define Py_tuple_MAXFREELIST 2000  // Maximum number of tuples of each size to save
-#  define PyList_MAXSAVESIZE 21     // Largest list size to save on freelist (minus one)
+#  define PyList_MAXSAVESIZE 13     // Largest list size to save on freelist (minus one)
 #  define Py_small_lists_MAXFREELIST 40
 #  define Py_lists_MAXFREELIST 80
 #  define Py_list_iters_MAXFREELIST 10

From 76799fcc172d8a0333fc9a554dadd7ae799a477e Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Thu, 3 Apr 2025 21:23:08 +0000
Subject: [PATCH 09/13] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../2025-04-03-21-23-05.gh-issue-126703.6JpmrR.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-04-03-21-23-05.gh-issue-126703.6JpmrR.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-04-03-21-23-05.gh-issue-126703.6JpmrR.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-03-21-23-05.gh-issue-126703.6JpmrR.rst
new file mode 100644
index 000000000000000..2890b782cfdd488
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-03-21-23-05.gh-issue-126703.6JpmrR.rst
@@ -0,0 +1 @@
+Improve performance of :class:`list` by using dedicated freelists for small sizes.

From ce8c2e049e1641ce745baf9c905fbe0be40e64c1 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Sun, 6 Apr 2025 22:38:45 +0200
Subject: [PATCH 10/13] cleanup

---
 Objects/listobject.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 05ab7241df1468f..704fb1df781f338 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -262,7 +262,6 @@ _PyList_DebugMallocStats(FILE *out)
 static inline int
 maybe_small_list_freelist_push(PyObject *self)
 {
-    // todo: in the resizing there are some alignments on the allocation. can we use that here?
     assert(PyList_CheckExact(self));
 
     PyListObject *op = (PyListObject *)self;
@@ -287,17 +286,15 @@ PyList_New(Py_ssize_t size)
     if (size < PyList_MAXSAVESIZE) {
         op = (PyListObject *)_Py_FREELIST_POP(PyLongObject, small_lists[size]);
         if (op) {
+            assert (op->allocated >= size);
             // allocated with ob_item still allocated, but we need to set the other fields
             Py_SET_SIZE(op, size);
             if ( size>0) {
                 memset(op->ob_item, 0, size * sizeof(PyObject *));
             } else {
-                // might be relatex later
                 op->ob_item = NULL;
             }
-            assert (op->allocated >= size);
         }
-        //op=0;
     }
     if (op == NULL) {
         // do we still need this freelist? if so, we could store it at small_lists[0] with some special casing

From 6bf65c7884e5c410d06f596f114c457bac49f0d3 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Tue, 8 Apr 2025 22:47:57 +0200
Subject: [PATCH 11/13] update comment

---
 Objects/listobject.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 704fb1df781f338..48157a5d013c555 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -297,7 +297,7 @@ PyList_New(Py_ssize_t size)
         }
     }
     if (op == NULL) {
-        // do we still need this freelist? if so, we could store it at small_lists[0] with some special casing
+        // the size based freelist was empty, so we try the general freelist
         op = _Py_FREELIST_POP(PyListObject, lists);
         if (op == NULL) {
             op = PyObject_GC_New(PyListObject, &PyList_Type);

From 69dd56b38215a73bf7f085726e3ab9baa51439a5 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Tue, 8 Apr 2025 22:49:01 +0200
Subject: [PATCH 12/13] update comment

---
 Objects/listobject.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 48157a5d013c555..4d5a2c6e01e16e6 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -339,7 +339,6 @@ list_new_prealloc(Py_ssize_t size)
     if (size < PyList_MAXSAVESIZE) {
         PyListObject *op = (PyListObject *)_Py_FREELIST_POP(PyLongObject, small_lists[size]);
         if (op) {
-            // allocated with ob_item still allocated, but we need to set the other fields
             assert (op->allocated >= size);
             return (PyObject *) op;
         }

From eb0a0d832cb7752ab4b99a5b299472d37329dd73 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Langa?= <lukasz@langa.pl>
Date: Wed, 21 Oct 2026 03:27:43 +0200
Subject: [PATCH 13/13] Fix CI: force fresh list buffer alloc in test_no_memory
 (gh-126703)

Small-list freelist entries keep their ob_item buffers, so a plain [None]
after inject_memory_error() may succeed instead of failing. Repeat the list
to a size the freelists cannot satisfy, forcing a real allocation.

Co-authored-by: Muse Code (Meta Muse Spark)
---
 Lib/test/test_list.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index 9341727b970ef42..070e4590f57df9a 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -384,7 +384,9 @@ def test_no_memory(self):
              None, None, None, None, None, None, None, None, None,]
         del l
         support.inject_memory_error()
-        l = [None]
+        # Repeat to force a fresh ob_item allocation: entries on the small
+        # list freelists keep their buffers, so a plain [None] may succeed.
+        l = [None] * 30
         """)
         rc, _, _ = assert_python_failure("-c", code)
         if support.MS_WINDOWS: