Added some statistics code to dict and list object code. I wanted to test how a larger freelist affects the reusage of freed objects. Contrary to my gut feelings 80 objects is more than fine for small apps. I haven't profiled a large app yet.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index e0ac475..82d247f 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -162,6 +162,22 @@
}
#endif
+/* Debug statistic to compare allocations with reuse through the free list */
+#undef SHOW_ALLOC_COUNT
+#ifdef SHOW_ALLOC_COUNT
+static size_t count_alloc = 0;
+static size_t count_reuse = 0;
+
+static void
+show_alloc(void)
+{
+ fprintf(stderr, "Dict allocations: %zd\n", count_alloc);
+ fprintf(stderr, "Dict reuse through freelist: %zd\n", count_reuse);
+ fprintf(stderr, "%.2f%% reuse rate\n\n",
+ (100.0*count_reuse/(count_alloc+count_reuse)));
+}
+#endif
+
/* Initialization macros.
There are two ways to create a dict: PyDict_New() is the main C API
function, and the tp_new slot maps to dict_new(). In the latter case we
@@ -200,6 +216,9 @@
#ifdef SHOW_CONVERSION_COUNTS
Py_AtExit(show_counts);
#endif
+#ifdef SHOW_ALLOC_COUNT
+ Py_AtExit(show_alloc);
+#endif
}
if (numfree) {
mp = free_list[--numfree];
@@ -212,11 +231,17 @@
assert (mp->ma_used == 0);
assert (mp->ma_table == mp->ma_smalltable);
assert (mp->ma_mask == PyDict_MINSIZE - 1);
+#ifdef SHOW_ALLOC_COUNT
+ count_reuse++;
+#endif
} else {
mp = PyObject_GC_New(PyDictObject, &PyDict_Type);
if (mp == NULL)
return NULL;
EMPTY_TO_MINSIZE(mp);
+#ifdef SHOW_ALLOC_COUNT
+ count_alloc++;
+#endif
}
mp->ma_lookup = lookdict_string;
#ifdef SHOW_CONVERSION_COUNTS