New submission from Daniel <danie...@fixedit.ai>:
Hello,
When embedding Python into a C application and not using Py_RunMain it is not
possible to remove a module added to PyImport_Inittab even if the interpreter
is finalized and a new is created.
One reason for not using Py_RunMain is to use python as a subprocessor to my
primary C application by initializing an interpreter, run some python code,
then go back to execute some C code and again execute some python code in the
same interpreter. After a while I might want to finalize the interpreter and
create a new one without the module added to inittab, still being in the same
process.
See example:
#include <Python.h>
/*
* Create a python interpreter, run a command and delete the interpreter
*/
void run_in_new_interpreter(char *cmd) {
Py_Initialize();
PyRun_SimpleString(cmd);
if (Py_FinalizeEx() < 0) {
exit(120);
}
}
/*
* Create a module "my_spam" but do not append it to inittab
*/
static PyModuleDef EmbModule = {
PyModuleDef_HEAD_INIT, "my_spam", NULL, -1,
NULL,
NULL, NULL, NULL, NULL
};
static PyObject* PyInit_emb(void) {
return PyModule_Create(&EmbModule);
}
/*
* Main program
*/
char *LIST_MODULES_CMD="try:\n import my_spam; print('SPAM!');\nexcept:\n
print('no mod my_spam')";
int main(int argc, char *argv[]) {
// Run with no "my_spam" module
run_in_new_interpreter(LIST_MODULES_CMD);
// Run with "my_spam" module
PyImport_AppendInittab("my_spam", &PyInit_emb);
run_in_new_interpreter(LIST_MODULES_CMD);
// How to run without my_spam? The module is still in the PyImport_Inittab
// despite the Py_FinalizeEx() call. This list is not reset until
// _PyImport_Fini2() is called, but that is never exposed in anyi public
header,
// only in Include/internal/pycore_pylifecycle.h
run_in_new_interpreter(LIST_MODULES_CMD);
return 0;
}
The output of the program is:
>>> gcc test_embed.c `pkg-config --cflags --libs python-3.6` && ./a.out
no mod my_spam
SPAM!
SPAM!
----------
components: C API
messages: 407590
nosy: daniel-falk
priority: normal
severity: normal
status: open
title: Not possible to clear PyImport_Inittab after PyImport_AppendInittab
type: behavior
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue45973>
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