bpo-40521: Disable Unicode caches in isolated subinterpreters (GH-19933)
When Python is built in the experimental isolated subinterpreters
mode, disable Unicode singletons and Unicode interned strings since
they are shared by all interpreters.
Temporary workaround until these caches are made per-interpreter.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index db0ae97..1565b90 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -56,6 +56,11 @@
static size_t method_cache_collisions = 0;
#endif
+/* bpo-40521: Interned strings are shared by all subinterpreters */
+#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
+# define INTERN_NAME_STRINGS
+#endif
+
/* alphabetical order */
_Py_IDENTIFIER(__abstractmethods__);
_Py_IDENTIFIER(__class__);
@@ -3418,6 +3423,7 @@
if (name == NULL)
return -1;
}
+#ifdef INTERN_NAME_STRINGS
if (!PyUnicode_CHECK_INTERNED(name)) {
PyUnicode_InternInPlace(&name);
if (!PyUnicode_CHECK_INTERNED(name)) {
@@ -3427,6 +3433,7 @@
return -1;
}
}
+#endif
}
else {
/* Will fail in _PyObject_GenericSetAttrWithDict. */
@@ -7531,10 +7538,17 @@
for (slotdef *p = slotdefs; p->name; p++) {
/* Slots must be ordered by their offset in the PyHeapTypeObject. */
assert(!p[1].name || p->offset <= p[1].offset);
+#ifdef INTERN_NAME_STRINGS
p->name_strobj = PyUnicode_InternFromString(p->name);
if (!p->name_strobj || !PyUnicode_CHECK_INTERNED(p->name_strobj)) {
return _PyStatus_NO_MEMORY();
}
+#else
+ p->name_strobj = PyUnicode_FromString(p->name);
+ if (!p->name_strobj) {
+ return _PyStatus_NO_MEMORY();
+ }
+#endif
}
slotdefs_initialized = 1;
return _PyStatus_OK();
@@ -7559,7 +7573,9 @@
int offset;
assert(PyUnicode_CheckExact(name));
+#ifdef INTERN_NAME_STRINGS
assert(PyUnicode_CHECK_INTERNED(name));
+#endif
assert(slotdefs_initialized);
pp = ptrs;
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index aba7407..18b9458 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -198,6 +198,11 @@
# define OVERALLOCATE_FACTOR 4
#endif
+/* bpo-40521: Interned strings are shared by all interpreters. */
+#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
+# define INTERNED_STRINGS
+#endif
+
/* This dictionary holds all interned unicode strings. Note that references
to strings in this dictionary are *not* counted in the string's ob_refcnt.
When the interned string reaches a refcnt of 0 the string deallocation
@@ -206,7 +211,9 @@
Another way to look at this is that to say that the actual reference
count of a string is: s->ob_refcnt + (s->state ? 2 : 0)
*/
+#ifdef INTERNED_STRINGS
static PyObject *interned = NULL;
+#endif
/* The empty Unicode object is shared to improve performance. */
static PyObject *unicode_empty = NULL;
@@ -281,9 +288,16 @@
/* List of static strings. */
static _Py_Identifier *static_strings = NULL;
+/* bpo-40521: Latin1 singletons are shared by all interpreters. */
+#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
+# define LATIN1_SINGLETONS
+#endif
+
+#ifdef LATIN1_SINGLETONS
/* Single character Unicode strings in the Latin-1 range are being
shared as well. */
static PyObject *unicode_latin1[256] = {NULL};
+#endif
/* Fast detection of the most frequent whitespace characters */
const unsigned char _Py_ascii_whitespace[] = {
@@ -662,6 +676,7 @@
return unicode_empty;
}
+#ifdef LATIN1_SINGLETONS
if (length == 1) {
const void *data = PyUnicode_DATA(unicode);
int kind = PyUnicode_KIND(unicode);
@@ -683,6 +698,7 @@
}
}
}
+#endif
assert(_PyUnicode_CheckConsistency(unicode, 1));
return unicode;
@@ -1913,10 +1929,12 @@
case SSTATE_INTERNED_MORTAL:
/* revive dead object temporarily for DelItem */
Py_SET_REFCNT(unicode, 3);
+#ifdef INTERNED_STRINGS
if (PyDict_DelItem(interned, unicode) != 0) {
_PyErr_WriteUnraisableMsg("deletion of interned string failed",
NULL);
}
+#endif
break;
case SSTATE_INTERNED_IMMORTAL:
@@ -1944,15 +1962,18 @@
static int
unicode_is_singleton(PyObject *unicode)
{
- PyASCIIObject *ascii = (PyASCIIObject *)unicode;
- if (unicode == unicode_empty)
+ if (unicode == unicode_empty) {
return 1;
+ }
+#ifdef LATIN1_SINGLETONS
+ PyASCIIObject *ascii = (PyASCIIObject *)unicode;
if (ascii->state.kind != PyUnicode_WCHAR_KIND && ascii->length == 1)
{
Py_UCS4 ch = PyUnicode_READ_CHAR(unicode, 0);
if (ch < 256 && unicode_latin1[ch] == unicode)
return 1;
}
+#endif
return 0;
}
#endif
@@ -2094,16 +2115,28 @@
static PyObject*
get_latin1_char(unsigned char ch)
{
- PyObject *unicode = unicode_latin1[ch];
- if (!unicode) {
- unicode = PyUnicode_New(1, ch);
- if (!unicode)
- return NULL;
- PyUnicode_1BYTE_DATA(unicode)[0] = ch;
- assert(_PyUnicode_CheckConsistency(unicode, 1));
- unicode_latin1[ch] = unicode;
+ PyObject *unicode;
+
+#ifdef LATIN1_SINGLETONS
+ unicode = unicode_latin1[ch];
+ if (unicode) {
+ Py_INCREF(unicode);
+ return unicode;
}
+#endif
+
+ unicode = PyUnicode_New(1, ch);
+ if (!unicode) {
+ return NULL;
+ }
+
+ PyUnicode_1BYTE_DATA(unicode)[0] = ch;
+ assert(_PyUnicode_CheckConsistency(unicode, 1));
+
+#ifdef LATIN1_SINGLETONS
Py_INCREF(unicode);
+ unicode_latin1[ch] = unicode;
+#endif
return unicode;
}
@@ -11270,7 +11303,6 @@
_PyUnicode_EqualToASCIIId(PyObject *left, _Py_Identifier *right)
{
PyObject *right_uni;
- Py_hash_t hash;
assert(_PyUnicode_CHECK(left));
assert(right->string);
@@ -11302,10 +11334,12 @@
if (PyUnicode_CHECK_INTERNED(left))
return 0;
+#ifdef INTERNED_STRINGS
assert(_PyUnicode_HASH(right_uni) != -1);
- hash = _PyUnicode_HASH(left);
+ Py_hash_t hash = _PyUnicode_HASH(left);
if (hash != -1 && hash != _PyUnicode_HASH(right_uni))
return 0;
+#endif
return unicode_compare_eq(left, right_uni);
}
@@ -15487,20 +15521,26 @@
PyUnicode_InternInPlace(PyObject **p)
{
PyObject *s = *p;
- PyObject *t;
#ifdef Py_DEBUG
assert(s != NULL);
assert(_PyUnicode_CHECK(s));
#else
- if (s == NULL || !PyUnicode_Check(s))
+ if (s == NULL || !PyUnicode_Check(s)) {
return;
+ }
#endif
+
/* If it's a subclass, we don't really know what putting
it in the interned dict might do. */
- if (!PyUnicode_CheckExact(s))
+ if (!PyUnicode_CheckExact(s)) {
return;
- if (PyUnicode_CHECK_INTERNED(s))
+ }
+
+ if (PyUnicode_CHECK_INTERNED(s)) {
return;
+ }
+
+#ifdef INTERNED_STRINGS
if (interned == NULL) {
interned = PyDict_New();
if (interned == NULL) {
@@ -15508,22 +15548,28 @@
return;
}
}
+
+ PyObject *t;
Py_ALLOW_RECURSION
t = PyDict_SetDefault(interned, s, s);
Py_END_ALLOW_RECURSION
+
if (t == NULL) {
PyErr_Clear();
return;
}
+
if (t != s) {
Py_INCREF(t);
Py_SETREF(*p, t);
return;
}
+
/* The two references in interned are not counted by refcnt.
The deallocator will take care of this */
Py_SET_REFCNT(s, Py_REFCNT(s) - 2);
_PyUnicode_STATE(s).interned = SSTATE_INTERNED_MORTAL;
+#endif
}
void
@@ -16109,9 +16155,11 @@
Py_CLEAR(unicode_empty);
+#ifdef LATIN1_SINGLETONS
for (Py_ssize_t i = 0; i < 256; i++) {
Py_CLEAR(unicode_latin1[i]);
}
+#endif
_PyUnicode_ClearStaticStrings();
}