Skip to content

gh-123471: Make concurrent iteration over itertools.permutations and itertools.combinations_with_replacement thread-safe #144402

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
colesbury merged 8 commits into from
Feb 4, 2026
Merged

gh-123471: Make concurrent iteration over itertools.permutations and itertools.combinations_with_replacement thread-safe #144402

Show file tree
Hide file tree
Changes from 4 commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
56b615e
Make itertools.combinations_with_replacement thread-safe
eendebakpt Feb 2, 2026
8139046
Make itertools.combinations_with_replacement thread-safe
eendebakpt Feb 2, 2026
6370bc4
Make permutations thread-safe
eendebakpt Feb 2, 2026
af909ce
remove redundant variable
eendebakpt Feb 2, 2026
dbb33bd
refactor code based on review
eendebakpt Feb 3, 2026
498f314
📜🤖 Added by blurb_it.
blurb-it[bot] Feb 3, 2026
c790b21
Apply suggestion from @eendebakpt
eendebakpt Feb 3, 2026
85540d3
Merge branch 'main' into cwr_ft
eendebakpt Feb 3, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
55 changes: 54 additions & 1 deletion Lib/test/test_free_threading/test_itertools.py
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
import unittest
from threading import Thread, Barrier
from itertools import batched, chain, cycle
from itertools import batched, chain, combinations_with_replacement, cycle, permutations
from test.support import threading_helper


Expand Down Expand Up @@ -89,6 +89,59 @@ def work(it):

barrier.reset()

@threading_helper.reap_threads
def test_combinations_with_replacement(self):
number_of_threads = 6
number_of_iterations = 36
data = tuple(range(2))

barrier = Barrier(number_of_threads)
def work(it):
barrier.wait()
while True:
try:
next(it)
except StopIteration:
break

for _ in range(number_of_iterations):
cwr_iterator = combinations_with_replacement(data, 2)
worker_threads = []
for _ in range(number_of_threads):
worker_threads.append(
Thread(target=work, args=[cwr_iterator]))

with threading_helper.start_threads(worker_threads):
pass

barrier.reset()
Comment thread
colesbury marked this conversation as resolved.
Outdated

@threading_helper.reap_threads
def test_permutations(self):
number_of_threads = 6
number_of_iterations = 36
data = tuple(range(4))

barrier = Barrier(number_of_threads)
def work(it):
barrier.wait()
while True:
try:
next(it)
except StopIteration:
break

for _ in range(number_of_iterations):
perm_iterator = permutations(data, 2)
worker_threads = []
for _ in range(number_of_threads):
worker_threads.append(
Thread(target=work, args=[perm_iterator]))

with threading_helper.start_threads(worker_threads):
pass

barrier.reset()


if __name__ == "__main__":
Expand Down
24 changes: 22 additions & 2 deletions Modules/itertoolsmodule.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2587,7 +2587,7 @@ cwr_traverse(PyObject *op, visitproc visit, void *arg)
}

static PyObject *
cwr_next(PyObject *op)
cwr_next_lock_held(PyObject *op)
{
cwrobject *co = cwrobject_CAST(op);
PyObject *elem;
Expand Down Expand Up @@ -2666,6 +2666,16 @@ cwr_next(PyObject *op)
return NULL;
}

static PyObject *
cwr_next(PyObject *op)
{
PyObject *result;
Py_BEGIN_CRITICAL_SECTION(op);
result = cwr_next_lock_held(op);
Py_END_CRITICAL_SECTION()
return result;
}

static PyMethodDef cwr_methods[] = {
{"__sizeof__", cwr_sizeof, METH_NOARGS, sizeof_doc},
{NULL, NULL} /* sentinel */
Expand Down Expand Up @@ -2846,7 +2856,7 @@ permutations_traverse(PyObject *op, visitproc visit, void *arg)
}

static PyObject *
permutations_next(PyObject *op)
permutations_next_lock_held(PyObject *op)
{
permutationsobject *po = permutationsobject_CAST(op);
PyObject *elem;
Expand Down Expand Up @@ -2936,6 +2946,16 @@ permutations_next(PyObject *op)
return NULL;
}

static PyObject *
permutations_next(PyObject *op)
{
PyObject *result;
Py_BEGIN_CRITICAL_SECTION(op);
result = permutations_next_lock_held(op);
Py_END_CRITICAL_SECTION()
return result;
}

static PyMethodDef permuations_methods[] = {
{"__sizeof__", permutations_sizeof, METH_NOARGS, sizeof_doc},
{NULL, NULL} /* sentinel */
Expand Down
Loading