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bpo-38858: Small integer per interpreter (GH-17315)

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Each Python subinterpreter now has its own "small integer
singletons": numbers in [-5; 257] range.

It is no longer possible to change the number of small integers at
build time by overriding NSMALLNEGINTS and NSMALLPOSINTS macros:
macros should now be modified manually in pycore_pystate.h header
file.

For now, continue to share _PyLong_Zero and _PyLong_One singletons
between all subinterpreters.
This commit is contained in:
Victor Stinner 2019-12-17 13:02:18 +01:00 • committed by GitHub
parent f501db2b93
commit 630c8df5cf
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
5 changed files with 57 additions and 38 deletions
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61
Objects/longobject.c
View file

@ -3,6 +3,7 @@
/* XXX The functional organization of this file is terrible */
#include "Python.h"
#include "pycore_pystate.h" /* _Py_IsMainInterpreter() */
#include "longintrepr.h"
#include <float.h>
@ -15,12 +16,8 @@ class int "PyObject *" "&PyLong_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=ec0275e3422a36e3]*/
#ifndef NSMALLPOSINTS
#define NSMALLPOSINTS 257
#endif
#ifndef NSMALLNEGINTS
#define NSMALLNEGINTS 5
#endif
#define NSMALLPOSINTS _PY_NSMALLPOSINTS
#define NSMALLNEGINTS _PY_NSMALLNEGINTS
_Py_IDENTIFIER(little);
_Py_IDENTIFIER(big);
@ -35,13 +32,6 @@ PyObject *_PyLong_Zero = NULL;
PyObject *_PyLong_One = NULL;
#if NSMALLNEGINTS + NSMALLPOSINTS > 0
/* Small integers are preallocated in this array so that they
can be shared.
The integers that are preallocated are those in the range
-NSMALLNEGINTS (inclusive) to NSMALLPOSINTS (not inclusive).
*/
static PyLongObject* small_ints[NSMALLNEGINTS + NSMALLPOSINTS] = {0};
#define IS_SMALL_INT(ival) (-NSMALLNEGINTS <= (ival) && (ival) < NSMALLPOSINTS)
#define IS_SMALL_UINT(ival) ((ival) < NSMALLPOSINTS)
@ -53,7 +43,8 @@ static PyObject *
get_small_int(sdigit ival)
{
assert(IS_SMALL_INT(ival));
PyObject *v = (PyObject*)small_ints[ival + NSMALLNEGINTS];
PyThreadState *tstate = _PyThreadState_GET();
PyObject *v = (PyObject*)tstate->interp->small_ints[ival + NSMALLNEGINTS];
Py_INCREF(v);
#ifdef COUNT_ALLOCS
if (ival >= 0)
@ -5782,7 +5773,7 @@ PyLong_GetInfo(void)
}
int
_PyLong_Init(void)
_PyLong_Init(PyThreadState *tstate)
{
#if NSMALLNEGINTS + NSMALLPOSINTS > 0
for (Py_ssize_t i=0; i < NSMALLNEGINTS + NSMALLPOSINTS; i++) {
@ -5797,37 +5788,43 @@ _PyLong_Init(void)
Py_SIZE(v) = size;
v->ob_digit[0] = (digit)abs(ival);
small_ints[i] = v;
tstate->interp->small_ints[i] = v;
}
#endif
_PyLong_Zero = PyLong_FromLong(0);
if (_PyLong_Zero == NULL) {
return 0;
}
_PyLong_One = PyLong_FromLong(1);
if (_PyLong_One == NULL) {
return 0;
}
/* initialize int_info */
if (Int_InfoType.tp_name == NULL) {
if (PyStructSequence_InitType2(&Int_InfoType, &int_info_desc) < 0) {
if (_Py_IsMainInterpreter(tstate)) {
_PyLong_Zero = PyLong_FromLong(0);
if (_PyLong_Zero == NULL) {
return 0;
}
_PyLong_One = PyLong_FromLong(1);
if (_PyLong_One == NULL) {
return 0;
}
/* initialize int_info */
if (Int_InfoType.tp_name == NULL) {
if (PyStructSequence_InitType2(&Int_InfoType, &int_info_desc) < 0) {
return 0;
}
}
}
return 1;
}
void
_PyLong_Fini(void)
_PyLong_Fini(PyThreadState *tstate)
{
Py_CLEAR(_PyLong_One);
Py_CLEAR(_PyLong_Zero);
if (_Py_IsMainInterpreter(tstate)) {
Py_CLEAR(_PyLong_One);
Py_CLEAR(_PyLong_Zero);
}
#if NSMALLNEGINTS + NSMALLPOSINTS > 0
for (Py_ssize_t i = 0; i < NSMALLNEGINTS + NSMALLPOSINTS; i++) {
Py_CLEAR(small_ints[i]);
Py_CLEAR(tstate->interp->small_ints[i]);
}
#endif
}