Merged revisions 70546 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r70546 | antoine.pitrou | 2009-03-23 19:41:45 +0100 (lun., 23 mars 2009) | 9 lines
Issue #4688: Add a heuristic so that tuples and dicts containing only
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)
........
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 8828a2d..11be0e1 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -23,11 +23,36 @@
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 @@
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, ...)
{
@@ -855,6 +906,9 @@
(void)PyTuple_ClearFreeList();
#endif
+#ifdef SHOW_TRACK_COUNT
+ show_track();
+#endif
}
/*********************** Tuple Iterator **************************/