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bpo-40521: Disable method cache in subinterpreters (GH-19960)

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When Python is built with experimental isolated interpreters, disable
the type method cache.

Temporary workaround until the cache is made per-interpreter.
This commit is contained in:
Victor Stinner 2020-05-06 18:23:58 +02:00 • committed by GitHub
parent 091951a67c
commit 89fc4a34cf
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 19 additions and 3 deletions
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22
Objects/typeobject.c
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@ -19,6 +19,12 @@ class object "PyObject *" "&PyBaseObject_Type"
#include "clinic/typeobject.c.h"
/* bpo-40521: Type method cache is shared by all subinterpreters */
#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
# define MCACHE
#endif
#ifdef MCACHE
/* Support type attribute cache */
/* The cache can keep references to the names alive for longer than
@ -47,6 +53,7 @@ struct method_cache_entry {
static struct method_cache_entry method_cache[1 << MCACHE_SIZE_EXP];
static unsigned int next_version_tag = 0;
#endif
#define MCACHE_STATS 0
@ -216,6 +223,7 @@ _PyType_GetTextSignatureFromInternalDoc(const char *name, const char *internal_d
unsigned int
PyType_ClearCache(void)
{
#ifdef MCACHE
Py_ssize_t i;
unsigned int cur_version_tag = next_version_tag - 1;
@ -240,6 +248,9 @@ PyType_ClearCache(void)
/* mark all version tags as invalid */
PyType_Modified(&PyBaseObject_Type);
return cur_version_tag;
#else
return 0;
#endif
}
void
@ -350,6 +361,7 @@ type_mro_modified(PyTypeObject *type, PyObject *bases) {
Py_TPFLAGS_VALID_VERSION_TAG);
}
#ifdef MCACHE
static int
assign_version_tag(PyTypeObject *type)
{
@ -396,6 +408,7 @@ assign_version_tag(PyTypeObject *type)
type->tp_flags |= Py_TPFLAGS_VALID_VERSION_TAG;
return 1;
}
#endif
static PyMemberDef type_members[] = {
@ -3232,12 +3245,12 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
{
PyObject *res;
int error;
unsigned int h;
#ifdef MCACHE
if (MCACHE_CACHEABLE_NAME(name) &&
_PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG)) {
/* fast path */
h = MCACHE_HASH_METHOD(type, name);
unsigned int h = MCACHE_HASH_METHOD(type, name);
if (method_cache[h].version == type->tp_version_tag &&
method_cache[h].name == name) {
#if MCACHE_STATS
@ -3246,6 +3259,7 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
return method_cache[h].value;
}
}
#endif
/* We may end up clearing live exceptions below, so make sure it's ours. */
assert(!PyErr_Occurred());
@ -3267,8 +3281,9 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
return NULL;
}
#ifdef MCACHE
if (MCACHE_CACHEABLE_NAME(name) && assign_version_tag(type)) {
h = MCACHE_HASH_METHOD(type, name);
unsigned int h = MCACHE_HASH_METHOD(type, name);
method_cache[h].version = type->tp_version_tag;
method_cache[h].value = res; /* borrowed */
Py_INCREF(name);
@ -3281,6 +3296,7 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
#endif
Py_SETREF(method_cache[h].name, name);
}
#endif
return res;
}