bpo-41796: Call _PyAST_Fini() earlier to fix a leak (GH-23131)

Call _PyAST_Fini() on all interpreters, not only on the main
interpreter. Also, call it ealier to fix a reference leak.

Python types contain a reference to themselves in in their
PyTypeObject.tp_mro member. _PyAST_Fini() must called before the last
GC collection to destroy AST types.

_PyInterpreterState_Clear() now calls _PyAST_Fini(). It now also
calls _PyWarnings_Fini() on subinterpeters, not only on the main
interpreter.

Add an assertion in AST init_types() to ensure that the _ast module
is no longer used after _PyAST_Fini() has been called.
This commit is contained in:
Victor Stinner 2020-11-03 18:07:15 +01:00 committed by GitHub
parent 212d32f45c
commit fd957c124c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 78 additions and 43 deletions

View File

@ -84,7 +84,7 @@ extern void _PyFaulthandler_Fini(void);
extern void _PyHash_Fini(void);
extern void _PyTraceMalloc_Fini(void);
extern void _PyWarnings_Fini(PyInterpreterState *interp);
extern void _PyAST_Fini(PyThreadState *tstate);
extern void _PyAST_Fini(PyInterpreterState *interp);
extern PyStatus _PyGILState_Init(PyThreadState *tstate);
extern void _PyGILState_Fini(PyThreadState *tstate);

View File

@ -1015,18 +1015,35 @@ static int add_ast_fields(struct ast_state *state)
""", 0, reflow=False)
self.emit("static int init_types(struct ast_state *state)",0)
self.emit("{", 0)
self.emit("if (state->initialized) return 1;", 1)
self.emit("if (init_identifiers(state) < 0) return 0;", 1)
self.emit("state->AST_type = PyType_FromSpec(&AST_type_spec);", 1)
self.emit("if (!state->AST_type) return 0;", 1)
self.emit("if (add_ast_fields(state) < 0) return 0;", 1)
self.file.write(textwrap.dedent('''
static int
init_types(struct ast_state *state)
{
// init_types() must not be called after _PyAST_Fini()
// has been called
assert(state->initialized >= 0);
if (state->initialized) {
return 1;
}
if (init_identifiers(state) < 0) {
return 0;
}
state->AST_type = PyType_FromSpec(&AST_type_spec);
if (!state->AST_type) {
return 0;
}
if (add_ast_fields(state) < 0) {
return 0;
}
'''))
for dfn in mod.dfns:
self.visit(dfn)
self.emit("state->initialized = 1;", 1)
self.emit("return 1;", 1);
self.emit("}", 0)
self.file.write(textwrap.dedent('''
state->initialized = 1;
return 1;
}
'''))
def visitProduct(self, prod, name):
if prod.fields:
@ -1353,23 +1370,27 @@ def generate_ast_state(module_state, f):
def generate_ast_fini(module_state, f):
f.write("""
void _PyAST_Fini(PyThreadState *tstate)
{
#ifdef Py_BUILD_CORE
struct ast_state *state = &tstate->interp->ast;
#else
struct ast_state *state = &global_ast_state;
#endif
f.write(textwrap.dedent("""
void _PyAST_Fini(PyInterpreterState *interp)
{
#ifdef Py_BUILD_CORE
struct ast_state *state = &interp->ast;
#else
struct ast_state *state = &global_ast_state;
#endif
""")
"""))
for s in module_state:
f.write(" Py_CLEAR(state->" + s + ');\n')
f.write("""
state->initialized = 0;
}
f.write(textwrap.dedent("""
#if defined(Py_BUILD_CORE) && !defined(NDEBUG)
state->initialized = -1;
#else
state->initialized = 0;
#endif
}
""")
"""))
def generate_module_def(mod, f, internal_h):

33
Python/Python-ast.c generated
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@ -261,10 +261,10 @@ get_ast_state(void)
#include "Python-ast.h"
#include "structmember.h"
void _PyAST_Fini(PyThreadState *tstate)
void _PyAST_Fini(PyInterpreterState *interp)
{
#ifdef Py_BUILD_CORE
struct ast_state *state = &tstate->interp->ast;
struct ast_state *state = &interp->ast;
#else
struct ast_state *state = &global_ast_state;
#endif
@ -483,7 +483,11 @@ void _PyAST_Fini(PyThreadState *tstate)
Py_CLEAR(state->vararg);
Py_CLEAR(state->withitem_type);
#if defined(Py_BUILD_CORE) && !defined(NDEBUG)
state->initialized = -1;
#else
state->initialized = 0;
#endif
}
static int init_identifiers(struct ast_state *state)
@ -1227,13 +1231,27 @@ static int add_ast_fields(struct ast_state *state)
}
static int init_types(struct ast_state *state)
static int
init_types(struct ast_state *state)
{
if (state->initialized) return 1;
if (init_identifiers(state) < 0) return 0;
// init_types() must not be called after _PyAST_Fini()
// has been called
assert(state->initialized >= 0);
if (state->initialized) {
return 1;
}
if (init_identifiers(state) < 0) {
return 0;
}
state->AST_type = PyType_FromSpec(&AST_type_spec);
if (!state->AST_type) return 0;
if (add_ast_fields(state) < 0) return 0;
if (!state->AST_type) {
return 0;
}
if (add_ast_fields(state) < 0) {
return 0;
}
state->mod_type = make_type(state, "mod", state->AST_type, NULL, 0,
"mod = Module(stmt* body, type_ignore* type_ignores)\n"
" | Interactive(stmt* body)\n"
@ -1902,6 +1920,7 @@ static int init_types(struct ast_state *state)
TypeIgnore_fields, 2,
"TypeIgnore(int lineno, string tag)");
if (!state->TypeIgnore_type) return 0;
state->initialized = 1;
return 1;
}

View File

@ -1545,12 +1545,6 @@ flush_std_files(void)
static void
finalize_interp_types(PyThreadState *tstate)
{
// The _ast module state is shared by all interpreters.
// The state must only be cleared by the main interpreter.
if (_Py_IsMainInterpreter(tstate)) {
_PyAST_Fini(tstate);
}
_PyExc_Fini(tstate);
_PyFrame_Fini(tstate);
_PyAsyncGen_Fini(tstate);
@ -1591,8 +1585,6 @@ finalize_interp_clear(PyThreadState *tstate)
_Py_ClearFileSystemEncoding();
}
_PyWarnings_Fini(tstate->interp);
finalize_interp_types(tstate);
}

View File

@ -300,13 +300,16 @@ interpreter_clear(PyInterpreterState *interp, PyThreadState *tstate)
Py_CLEAR(interp->after_forkers_parent);
Py_CLEAR(interp->after_forkers_child);
#endif
if (_PyRuntimeState_GetFinalizing(runtime) == NULL) {
_PyWarnings_Fini(interp);
}
_PyAST_Fini(interp);
_PyWarnings_Fini(interp);
// All Python types must be destroyed before the last GC collection. Python
// types create a reference cycle to themselves in their in their
// PyTypeObject.tp_mro member (the tuple contains the type).
/* Last garbage collection on this interpreter */
_PyGC_CollectNoFail(tstate);
_PyGC_Fini(tstate);
/* We don't clear sysdict and builtins until the end of this function.