[New-bugs-announce] [issue43145] Leak of locks in a subprocess

[Boris Staletic]

New submission from Boris Staletic <boris.staletic at gmail.com>:

The following C code leaks 7 locks allocated with PyThread_allocate_lock:

#include <Python.h>

int main()
{
	Py_Initialize();
	PyObject* multiprocessing = PyImport_ImportModule("multiprocessing");
	PyObject* Process = PyObject_GetAttrString(multiprocessing, "Process");
	PyObject* args = PyTuple_New(0);
	PyObject* kw = PyDict_New();
	PyDict_SetItemString(kw, "target", Process);

	PyObject* p = PyObject_Call(Process, args, kw);
	PyObject* start = PyObject_GetAttrString(p, "start");
	PyObject* join = PyObject_GetAttrString(p, "join");

	PyObject_CallNoArgs(start);
	PyObject_CallNoArgs(join);

	Py_DECREF(join);
	Py_DECREF(start);
	Py_DECREF(p);
	Py_DECREF(kw);
	Py_DECREF(args);
	Py_DECREF(Process);
	Py_DECREF(multiprocessing);
	Py_Finalize();
}



The following locks are leaked:

1. https://github.com/python/cpython/blob/196d4deaf4810a0bba75ba537dd40f2d71a5a634/Python/pystate.c#L78
2. https://github.com/python/cpython/blob/196d4deaf4810a0bba75ba537dd40f2d71a5a634/Python/pystate.c#L84
3. https://github.com/python/cpython/blob/196d4deaf4810a0bba75ba537dd40f2d71a5a634/Python/pystate.c#L90
4. https://github.com/python/cpython/blob/master/Python/ceval.c#L810
5. https://github.com/python/cpython/blob/master/Python/import.c#L126
6. and 7. https://github.com/python/cpython/blob/master/Modules/_threadmodule.c#L597

In the attachment is valgrind's output.

----------
components: C API
files: log
messages: 386558
nosy: bstaletic
priority: normal
severity: normal
status: open
title: Leak of locks in a subprocess
type: resource usage
versions: Python 3.10, Python 3.9
Added file: https://bugs.python.org/file49793/log

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43145>
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