[New-bugs-announce] [issue35943] PyImport_GetModule() can return partially-initialized module

[Antoine Pitrou]

New submission from Antoine Pitrou <pitrou at free.fr>:

PyImport_GetModule() returns whatever is in sys.modules, even if the module is still importing and therefore only partially initialized.

One possibility is to reuse the optimization already done in PyImport_ImportModuleLevelObject():

        /* Optimization: only call _bootstrap._lock_unlock_module() if
           __spec__._initializing is true.
           NOTE: because of this, initializing must be set *before*
           stuffing the new module in sys.modules.
         */
        spec = _PyObject_GetAttrId(mod, &PyId___spec__);
        if (_PyModuleSpec_IsInitializing(spec)) {
            PyObject *value = _PyObject_CallMethodIdObjArgs(interp->importlib,
                                            &PyId__lock_unlock_module, abs_name,
                                            NULL);
            if (value == NULL) {
                Py_DECREF(spec);
                goto error;
            }
            Py_DECREF(value);
        }
        Py_XDECREF(spec);

Issue originally mentioned in issue34572.

----------
components: Interpreter Core
messages: 335097
nosy: brett.cannon, eric.snow, ncoghlan, pitrou
priority: normal
severity: normal
stage: needs patch
status: open
title: PyImport_GetModule() can return partially-initialized module
type: behavior
versions: Python 3.7, Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35943>
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