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bpo-42208: Move _PyImport_Cleanup() to pylifecycle.c (pythonGH-23040)
Move _PyImport_Cleanup() to pylifecycle.c, rename it to finalize_modules(), split it (200 lines) into many smaller sub-functions and cleanup the code.
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Lines changed: 290 additions & 230 deletions

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‎Python/import.c‎

Lines changed: 0 additions & 227 deletions
Original file line numberDiff line numberDiff line change
@@ -406,233 +406,6 @@ import_ensure_initialized(PyThreadState *tstate, PyObject *mod, PyObject *name)
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}
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/* List of names to clear in sys */
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static const char * const sys_deletes[] = {
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"path", "argv", "ps1", "ps2",
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"last_type", "last_value", "last_traceback",
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"path_hooks", "path_importer_cache", "meta_path",
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"__interactivehook__",
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NULL
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};
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static const char * const sys_files[] = {
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"stdin", "__stdin__",
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"stdout", "__stdout__",
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"stderr", "__stderr__",
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NULL
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};
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/* Un-initialize things, as good as we can */
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void
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_PyImport_Cleanup(PyThreadState *tstate)
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{
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PyInterpreterState *interp = tstate->interp;
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PyObject *modules = interp->modules;
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if (modules == NULL) {
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/* Already done */
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return;
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}
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/* Delete some special variables first. These are common
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places where user values hide and people complain when their
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destructors fail. Since the modules containing them are
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deleted *last* of all, they would come too late in the normal
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destruction order. Sigh. */
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/* XXX Perhaps these precautions are obsolete. Who knows? */
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int verbose = _PyInterpreterState_GetConfig(interp)->verbose;
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if (verbose) {
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PySys_WriteStderr("# clear builtins._\n");
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}
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if (PyDict_SetItemString(interp->builtins, "_", Py_None) < 0) {
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PyErr_WriteUnraisable(NULL);
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}
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const char * const *p;
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for (p = sys_deletes; *p != NULL; p++) {
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if (verbose) {
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PySys_WriteStderr("# clear sys.%s\n", *p);
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}
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if (PyDict_SetItemString(interp->sysdict, *p, Py_None) < 0) {
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PyErr_WriteUnraisable(NULL);
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}
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}
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for (p = sys_files; *p != NULL; p+=2) {
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if (verbose) {
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PySys_WriteStderr("# restore sys.%s\n", *p);
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}
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PyObject *value = _PyDict_GetItemStringWithError(interp->sysdict,
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*(p+1));
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if (value == NULL) {
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if (_PyErr_Occurred(tstate)) {
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PyErr_WriteUnraisable(NULL);
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}
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value = Py_None;
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}
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if (PyDict_SetItemString(interp->sysdict, *p, value) < 0) {
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PyErr_WriteUnraisable(NULL);
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}
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}
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/* We prepare a list which will receive (name, weakref) tuples of
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modules when they are removed from sys.modules. The name is used
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for diagnosis messages (in verbose mode), while the weakref helps
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detect those modules which have been held alive. */
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PyObject *weaklist = PyList_New(0);
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if (weaklist == NULL) {
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PyErr_WriteUnraisable(NULL);
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}
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#define STORE_MODULE_WEAKREF(name, mod) \
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if (weaklist != NULL) { \
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PyObject *wr = PyWeakref_NewRef(mod, NULL); \
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if (wr) { \
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PyObject *tup = PyTuple_Pack(2, name, wr); \
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if (!tup || PyList_Append(weaklist, tup) < 0) { \
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PyErr_WriteUnraisable(NULL); \
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} \
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Py_XDECREF(tup); \
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Py_DECREF(wr); \
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} \
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else { \
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PyErr_WriteUnraisable(NULL); \
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} \
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}
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#define CLEAR_MODULE(name, mod) \
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if (PyModule_Check(mod)) { \
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if (verbose && PyUnicode_Check(name)) { \
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PySys_FormatStderr("# cleanup[2] removing %U\n", name); \
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} \
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STORE_MODULE_WEAKREF(name, mod); \
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if (PyObject_SetItem(modules, name, Py_None) < 0) { \
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PyErr_WriteUnraisable(NULL); \
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} \
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}
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/* Remove all modules from sys.modules, hoping that garbage collection
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can reclaim most of them. */
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if (PyDict_CheckExact(modules)) {
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Py_ssize_t pos = 0;
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PyObject *key, *value;
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while (PyDict_Next(modules, &pos, &key, &value)) {
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CLEAR_MODULE(key, value);
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}
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}
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else {
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PyObject *iterator = PyObject_GetIter(modules);
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if (iterator == NULL) {
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PyErr_WriteUnraisable(NULL);
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}
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else {
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PyObject *key;
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while ((key = PyIter_Next(iterator))) {
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PyObject *value = PyObject_GetItem(modules, key);
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if (value == NULL) {
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PyErr_WriteUnraisable(NULL);
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continue;
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}
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CLEAR_MODULE(key, value);
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Py_DECREF(value);
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Py_DECREF(key);
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}
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if (PyErr_Occurred()) {
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PyErr_WriteUnraisable(NULL);
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}
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Py_DECREF(iterator);
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}
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}
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/* Clear the modules dict. */
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if (PyDict_CheckExact(modules)) {
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PyDict_Clear(modules);
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}
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else {
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_Py_IDENTIFIER(clear);
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if (_PyObject_CallMethodIdNoArgs(modules, &PyId_clear) == NULL) {
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PyErr_WriteUnraisable(NULL);
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}
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}
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/* Restore the original builtins dict, to ensure that any
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user data gets cleared. */
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PyObject *dict = PyDict_Copy(interp->builtins);
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if (dict == NULL) {
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PyErr_WriteUnraisable(NULL);
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}
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PyDict_Clear(interp->builtins);
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if (PyDict_Update(interp->builtins, interp->builtins_copy)) {
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_PyErr_Clear(tstate);
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}
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Py_XDECREF(dict);
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/* Collect references */
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_PyGC_CollectNoFail(tstate);
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/* Dump GC stats before it's too late, since it uses the warnings
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machinery. */
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_PyGC_DumpShutdownStats(tstate);
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/* Now, if there are any modules left alive, clear their globals to
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minimize potential leaks. All C extension modules actually end
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up here, since they are kept alive in the interpreter state.
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The special treatment of "builtins" here is because even
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when it's not referenced as a module, its dictionary is
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referenced by almost every module's __builtins__. Since
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deleting a module clears its dictionary (even if there are
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references left to it), we need to delete the "builtins"
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module last. Likewise, we don't delete sys until the very
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end because it is implicitly referenced (e.g. by print). */
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if (weaklist != NULL) {
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Py_ssize_t i;
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/* Since dict is ordered in CPython 3.6+, modules are saved in
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importing order. First clear modules imported later. */
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for (i = PyList_GET_SIZE(weaklist) - 1; i >= 0; i--) {
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PyObject *tup = PyList_GET_ITEM(weaklist, i);
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PyObject *name = PyTuple_GET_ITEM(tup, 0);
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PyObject *mod = PyWeakref_GET_OBJECT(PyTuple_GET_ITEM(tup, 1));
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if (mod == Py_None)
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continue;
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assert(PyModule_Check(mod));
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dict = PyModule_GetDict(mod);
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if (dict == interp->builtins || dict == interp->sysdict)
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continue;
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Py_INCREF(mod);
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if (verbose && PyUnicode_Check(name)) {
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PySys_FormatStderr("# cleanup[3] wiping %U\n", name);
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}
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_PyModule_Clear(mod);
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Py_DECREF(mod);
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}
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Py_DECREF(weaklist);
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}
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/* Next, delete sys and builtins (in that order) */
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if (verbose) {
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PySys_FormatStderr("# cleanup[3] wiping sys\n");
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}
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_PyModule_ClearDict(interp->sysdict);
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if (verbose) {
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PySys_FormatStderr("# cleanup[3] wiping builtins\n");
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}
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_PyModule_ClearDict(interp->builtins);
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/* Clear module dict copies stored in the interpreter state */
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_PyInterpreterState_ClearModules(interp);
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/* Clear and delete the modules directory. Actual modules will
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still be there only if imported during the execution of some
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destructor. */
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interp->modules = NULL;
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Py_DECREF(modules);
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/* Once more */
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_PyGC_CollectNoFail(tstate);
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#undef CLEAR_MODULE
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#undef STORE_MODULE_WEAKREF
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}
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/* Helper for pythonrun.c -- return magic number and tag. */
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long

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