mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-04 08:59:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 11

Issue #14435: Remove special block allocation code from floatobject.c

Browse source 
PyFloatObjects are now allocated using PyObject_MALLOC like all other
internal types, but maintain a limited freelist of objects at hand for
performance.  This will result in more consistent memory usage by Python.
This commit is contained in:
Kristján Valur Jónsson 2012-03-30 09:18:15 +00:00
parent c1d9869cb9
commit daa06544c8
1 changed files with 27 additions and 131 deletions
Download patch file Download diff file Expand all files Collapse all files

158
Objects/floatobject.c
View file

@ -16,53 +16,16 @@
/* Special free list
Since some Python programs can spend much of their time allocating
and deallocating floats, these operations should be very fast.
Therefore we use a dedicated allocation scheme with a much lower
overhead (in space and time) than straight malloc(): a simple
dedicated free list, filled when necessary with memory from malloc().
block_list is a singly-linked list of all PyFloatBlocks ever allocated,
linked via their next members. PyFloatBlocks are never returned to the
system before shutdown (PyFloat_Fini).
free_list is a singly-linked list of available PyFloatObjects, linked
via abuse of their ob_type members.
*/
#define BLOCK_SIZE 1000 /* 1K less typical malloc overhead */
#define BHEAD_SIZE 8 /* Enough for a 64-bit pointer */
#define N_FLOATOBJECTS ((BLOCK_SIZE - BHEAD_SIZE) / sizeof(PyFloatObject))
struct _floatblock {
struct _floatblock *next;
PyFloatObject objects[N_FLOATOBJECTS];
};
typedef struct _floatblock PyFloatBlock;
static PyFloatBlock *block_list = NULL;
#ifndef PyFloat_MAXFREELIST
#define PyFloat_MAXFREELIST 100
#endif
static int numfree = 0;
static PyFloatObject *free_list = NULL;
static PyFloatObject *
fill_free_list(void)
{
PyFloatObject *p, *q;
/* XXX Float blocks escape the object heap. Use PyObject_MALLOC ??? */
p = (PyFloatObject *) PyMem_MALLOC(sizeof(PyFloatBlock));
if (p == NULL)
return (PyFloatObject *) PyErr_NoMemory();
((PyFloatBlock *)p)->next = block_list;
block_list = (PyFloatBlock *)p;
p = &((PyFloatBlock *)p)->objects[0];
q = p + N_FLOATOBJECTS;
while (--q > p)
Py_TYPE(q) = (struct _typeobject *)(q-1);
Py_TYPE(q) = NULL;
return p + N_FLOATOBJECTS - 1;
}
double
PyFloat_GetMax(void)
{
@ -151,14 +114,16 @@ PyFloat_GetInfo(void)
PyObject *
PyFloat_FromDouble(double fval)
{
register PyFloatObject *op;
if (free_list == NULL) {
if ((free_list = fill_free_list()) == NULL)
return NULL;
register PyFloatObject *op = free_list;
if (op != NULL) {
free_list = (PyFloatObject *) Py_TYPE(op);
numfree--;
} else {
op = (PyFloatObject*) PyObject_MALLOC(sizeof(PyFloatObject));
if (!op)
return PyErr_NoMemory();
}
/* Inline PyObject_New */
op = free_list;
free_list = (PyFloatObject *)Py_TYPE(op);
PyObject_INIT(op, &PyFloat_Type);
op->ob_fval = fval;
return (PyObject *) op;
@ -217,6 +182,11 @@ static void
float_dealloc(PyFloatObject *op)
{
if (PyFloat_CheckExact(op)) {
if (numfree >= PyFloat_MAXFREELIST) {
PyObject_FREE(op);
return;
}
numfree++;
Py_TYPE(op) = (struct _typeobject *)free_list;
free_list = op;
}
@ -1932,96 +1902,22 @@ _PyFloat_Init(void)
int
PyFloat_ClearFreeList(void)
{
PyFloatObject *p;
PyFloatBlock *list, *next;
int i;
int u; /* remaining unfreed floats per block */
int freelist_size = 0;
list = block_list;
block_list = NULL;
free_list = NULL;
while (list != NULL) {
u = 0;
for (i = 0, p = &list->objects[0];
i < N_FLOATOBJECTS;
i++, p++) {
if (PyFloat_CheckExact(p) && Py_REFCNT(p) != 0)
u++;
}
next = list->next;
if (u) {
list->next = block_list;
block_list = list;
for (i = 0, p = &list->objects[0];
i < N_FLOATOBJECTS;
i++, p++) {
if (!PyFloat_CheckExact(p) ||
Py_REFCNT(p) == 0) {
Py_TYPE(p) = (struct _typeobject *)
free_list;
free_list = p;
}
}
}
else {
PyMem_FREE(list);
}
freelist_size += u;
list = next;
PyFloatObject *f = free_list, *next;
int i = numfree;
while (f) {
next = (PyFloatObject*) Py_TYPE(f);
PyObject_FREE(f);
f = next;
}
return freelist_size;
free_list = NULL;
numfree = 0;
return i;
}
void
PyFloat_Fini(void)
{
PyFloatObject *p;
PyFloatBlock *list;
int i;
int u; /* total unfreed floats per block */
u = PyFloat_ClearFreeList();
if (!Py_VerboseFlag)
return;
fprintf(stderr, "# cleanup floats");
if (!u) {
fprintf(stderr, "\n");
}
else {
fprintf(stderr,
": %d unfreed float%s\n",
u, u == 1 ? "" : "s");
}
if (Py_VerboseFlag > 1) {
list = block_list;
while (list != NULL) {
for (i = 0, p = &list->objects[0];
i < N_FLOATOBJECTS;
i++, p++) {
if (PyFloat_CheckExact(p) &&
Py_REFCNT(p) != 0) {
char *buf = PyOS_double_to_string(
PyFloat_AS_DOUBLE(p), 'r',
0, 0, NULL);
if (buf) {
/* XXX(twouters) cast
refcount to long
until %zd is
universally
available
*/
fprintf(stderr,
"# <float at %p, refcnt=%ld, val=%s>\n",
p, (long)Py_REFCNT(p), buf);
PyMem_Free(buf);
}
}
}
list = list->next;
}
}
(void)PyFloat_ClearFreeList();
}
/*----------------------------------------------------------------------------