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GH-93533: Shrink the LOAD_ATTR caches #103014

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brandtbucher wants to merge 7 commits into from
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GH-93533: Shrink the LOAD_ATTR caches #103014

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c87e8bd
Stick a small, resizable cache on all types
brandtbucher Mar 23, 2023
0e21f47
Try a bigger starting cache size (8 instead of 1)
brandtbucher Mar 23, 2023
bde6bec
Try a fixed cache size
brandtbucher Mar 23, 2023
212046c
Bump the size to 16
brandtbucher Mar 23, 2023
1ee7d47
Catch up with main
brandtbucher Mar 24, 2023
cdc3189
Blurb add
brandtbucher Mar 24, 2023
6934d55
Merge branch 'main' into type-cache-fixed
hugovk Mar 25, 2023
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Try a fixed cache size
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@brandtbucher
brandtbucher committed Mar 23, 2023
commit bde6bec49a139ad2ea6f78790c9b9cd0889777af
3 changes: 1 addition & 2 deletions Doc/includes/typestruct.h
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Expand Up @@ -81,9 +81,8 @@ typedef struct _typeobject {
destructor tp_finalize;
vectorcallfunc tp_vectorcall;

unsigned int _tp_cache_size;
unsigned int _tp_cache_used;
PyObject **_tp_cache;
PyObject *_tp_cache[_TP_CACHE_SIZE];

/* bitset of which type-watchers care about this type */
char tp_watched;
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5 changes: 3 additions & 2 deletions Include/cpython/object.h
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Expand Up @@ -141,6 +141,8 @@ typedef struct {
* backwards-compatibility */
typedef Py_ssize_t printfunc;

#define _TP_CACHE_SIZE (1 << 3)

// If this structure is modified, Doc/includes/typestruct.h should be updated
// as well.
struct _typeobject {
Expand Down Expand Up @@ -226,9 +228,8 @@ struct _typeobject {
destructor tp_finalize;
vectorcallfunc tp_vectorcall;

unsigned int _tp_cache_size;
unsigned int _tp_cache_used;
PyObject **_tp_cache;
PyObject *_tp_cache[_TP_CACHE_SIZE];

/* bitset of which type-watchers care about this type */
char tp_watched;
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2 changes: 1 addition & 1 deletion Lib/test/test_sys.py
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Expand Up @@ -1545,7 +1545,7 @@ def delx(self): del self.__x
check((1,2,3), vsize('') + 3*self.P)
# type
# static type: PyTypeObject
fmt = 'P2nPI13Pl4Pn9Pn12PIPIIPc'
fmt = 'P2nPI13Pl4Pn9Pn12PIPI8Pc'
s = vsize('2P' + fmt)
check(int, s)
# class
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4 changes: 0 additions & 4 deletions Objects/typeobject.c
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Expand Up @@ -4496,10 +4496,7 @@ _PyStaticType_Dealloc(PyTypeObject *type)
static_builtin_state_clear(type);
/* We leave _Py_TPFLAGS_STATIC_BUILTIN set on tp_flags. */
}
type->_tp_cache_size = 0;
type->_tp_cache_used = 0;
PyMem_Free(type->_tp_cache);
type->_tp_cache = NULL;
}


Expand All @@ -4523,7 +4520,6 @@ type_dealloc(PyTypeObject *type)
Py_XDECREF(type->tp_mro);
Py_XDECREF(type->tp_cache);
clear_subclasses(type);
PyMem_Free(type->_tp_cache);

/* A type's tp_doc is heap allocated, unlike the tp_doc slots
* of most other objects. It's okay to cast it to char *.
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14 changes: 4 additions & 10 deletions Python/specialize.c
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Expand Up @@ -489,17 +489,11 @@ insert_into_cache(PyTypeObject *type, PyObject *descr)
return i;
}
}
if (type->_tp_cache_used == type->_tp_cache_size) {
type->_tp_cache_size = Py_MAX(type->_tp_cache_size << 1, 8);
PyMem_Resize(type->_tp_cache, PyObject *, type->_tp_cache_size);
if (type->_tp_cache == NULL) {
type->_tp_cache_size = 0;
type->_tp_cache_used = 0;
return -1;
}
if (type->_tp_cache_used < _TP_CACHE_SIZE) {
type->_tp_cache[type->_tp_cache_used] = descr;
return type->_tp_cache_used++;
}
type->_tp_cache[type->_tp_cache_used] = descr;
return type->_tp_cache_used++;
return -1;
}

static int
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