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Issue #4688: Add a heuristic so that tuples and dicts containing only

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untrackable objects are not tracked by the garbage collector. This can
reduce the size of collections and therefore the garbage collection overhead
on long-running programs, depending on their particular use of datatypes.

(trivia: this makes the "binary_trees" benchmark from the Computer Language
Shootout 40% faster)
This commit is contained in:
Antoine Pitrou 2009-03-23 18:41:45 +00:00
parent e5b78563b6
commit f8387af262
11 changed files with 401 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

54
Objects/tupleobject.c
View file

@ -23,11 +23,36 @@ Py_ssize_t fast_tuple_allocs;
Py_ssize_t tuple_zero_allocs;
#endif
/* Debug statistic to count GC tracking of tuples.
Please note that tuples are only untracked when considered by the GC, and
many of them will be dead before. Therefore, a tracking rate close to 100%
does not necessarily prove that the heuristic is inefficient.
*/
#ifdef SHOW_TRACK_COUNT
static Py_ssize_t count_untracked = 0;
static Py_ssize_t count_tracked = 0;
static void
show_track(void)
{
fprintf(stderr, "Tuples created: %" PY_FORMAT_SIZE_T "d\n",
count_tracked + count_untracked);
fprintf(stderr, "Tuples tracked by the GC: %" PY_FORMAT_SIZE_T
"d\n", count_tracked);
fprintf(stderr, "%.2f%% tuple tracking rate\n\n",
(100.0*count_tracked/(count_untracked+count_tracked)));
}
#endif
PyObject *
PyTuple_New(register Py_ssize_t size)
{
register PyTupleObject *op;
Py_ssize_t i;
#ifdef SHOW_TRACK_COUNT
count_tracked++;
#endif
if (size < 0) {
PyErr_BadInternalCall();
return NULL;
@ -131,6 +156,32 @@ PyTuple_SetItem(register PyObject *op, register Py_ssize_t i, PyObject *newitem)
return 0;
}
void
_PyTuple_MaybeUntrack(PyObject *op)
{
PyTupleObject *t;
Py_ssize_t i, n;
if (!PyTuple_CheckExact(op) || !_PyObject_GC_IS_TRACKED(op))
return;
t = (PyTupleObject *) op;
n = Py_SIZE(t);
for (i = 0; i < n; i++) {
PyObject *elt = PyTuple_GET_ITEM(t, i);
/* Tuple with NULL elements aren't
fully constructed, don't untrack
them yet. */
if (!elt ||
_PyObject_GC_MAY_BE_TRACKED(elt))
return;
}
#ifdef SHOW_TRACK_COUNT
count_tracked--;
count_untracked++;
#endif
_PyObject_GC_UNTRACK(op);
}
PyObject *
PyTuple_Pack(Py_ssize_t n, ...)
{
@ -880,6 +931,9 @@ PyTuple_Fini(void)
(void)PyTuple_ClearFreeList();
#endif
#ifdef SHOW_TRACK_COUNT
show_track();
#endif
}
/*********************** Tuple Iterator **************************/