https://github.com/python/cpython/commit/92564331defba3462116d54658cd97624bb12678
commit: 92564331defba3462116d54658cd97624bb12678
branch: 3.12
author: Sam Gross <[email protected]>
committer: colesbury <[email protected]>
date: 2024-03-19T15:22:42-04:00
summary:
[3.12] gh-113964: Don't prevent new threads until all non-daemon threads exit
(GH-116677) (#117029)
Starting in Python 3.12, we prevented calling fork() and starting new threads
during interpreter finalization (shutdown). This has led to a number of
regressions and flaky tests. We should not prevent starting new threads
(or `fork()`) until all non-daemon threads exit and finalization starts in
earnest.
This changes the checks to use `_PyInterpreterState_GetFinalizing(interp)`,
which is set immediately before terminating non-daemon threads.
(cherry picked from commit 60e105c1c11ecca1680d03c38aa06bcc77a28714)
files:
A Misc/NEWS.d/next/Core and
Builtins/2024-03-12-20-31-57.gh-issue-113964.bJppzg.rst
M Lib/test/test_os.py
M Lib/test/test_subprocess.py
M Lib/test/test_threading.py
M Modules/_posixsubprocess.c
M Modules/_threadmodule.c
M Modules/posixmodule.c
M Objects/unicodeobject.c
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 46aec219c13673..e8f80046649cd4 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -4840,20 +4840,21 @@ def test_fork_warns_when_non_python_thread_exists(self):
self.assertEqual(err.decode("utf-8"), "")
self.assertEqual(out.decode("utf-8"), "")
- def test_fork_at_exit(self):
+ def test_fork_at_finalization(self):
code = """if 1:
import atexit
import os
- def exit_handler():
- pid = os.fork()
- if pid != 0:
- print("shouldn't be printed")
-
- atexit.register(exit_handler)
+ class AtFinalization:
+ def __del__(self):
+ print("OK")
+ pid = os.fork()
+ if pid != 0:
+ print("shouldn't be printed")
+ at_finalization = AtFinalization()
"""
_, out, err = assert_python_ok("-c", code)
- self.assertEqual(b"", out)
+ self.assertEqual(b"OK\n", out)
self.assertIn(b"can't fork at interpreter shutdown", err)
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index d83bd9be140616..79efa42791bb2c 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -3413,14 +3413,15 @@ def test_preexec_at_exit(self):
def dummy():
pass
- def exit_handler():
- subprocess.Popen({ZERO_RETURN_CMD}, preexec_fn=dummy)
- print("shouldn't be printed")
-
- atexit.register(exit_handler)
+ class AtFinalization:
+ def __del__(self):
+ print("OK")
+ subprocess.Popen({ZERO_RETURN_CMD}, preexec_fn=dummy)
+ print("shouldn't be printed")
+ at_finalization = AtFinalization()
"""
_, out, err = assert_python_ok("-c", code)
- self.assertEqual(out, b'')
+ self.assertEqual(out.strip(), b"OK")
self.assertIn(b"preexec_fn not supported at interpreter shutdown", err)
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index 119b41f39245ca..2e4b860b975ff8 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -1133,21 +1133,21 @@ def import_threading():
self.assertEqual(out, b'')
self.assertEqual(err, b'')
- def test_start_new_thread_at_exit(self):
+ def test_start_new_thread_at_finalization(self):
code = """if 1:
- import atexit
import _thread
def f():
print("shouldn't be printed")
- def exit_handler():
- _thread.start_new_thread(f, ())
-
- atexit.register(exit_handler)
+ class AtFinalization:
+ def __del__(self):
+ print("OK")
+ _thread.start_new_thread(f, ())
+ at_finalization = AtFinalization()
"""
_, out, err = assert_python_ok("-c", code)
- self.assertEqual(out, b'')
+ self.assertEqual(out.strip(), b"OK")
self.assertIn(b"can't create new thread at interpreter shutdown", err)
class ThreadJoinOnShutdown(BaseTestCase):
@@ -1276,6 +1276,30 @@ def main():
rc, out, err = assert_python_ok('-c', script)
self.assertFalse(err)
+ def test_thread_from_thread(self):
+ script = """if True:
+ import threading
+ import time
+
+ def thread2():
+ time.sleep(0.05)
+ print("OK")
+
+ def thread1():
+ time.sleep(0.05)
+ t2 = threading.Thread(target=thread2)
+ t2.start()
+
+ t = threading.Thread(target=thread1)
+ t.start()
+ # do not join() -- the interpreter waits for non-daemon threads to
+ # finish.
+ """
+ rc, out, err = assert_python_ok('-c', script)
+ self.assertEqual(err, b"")
+ self.assertEqual(out.strip(), b"OK")
+ self.assertEqual(rc, 0)
+
@skip_unless_reliable_fork
def test_reinit_tls_after_fork(self):
# Issue #13817: fork() would deadlock in a multithreaded program with
diff --git a/Misc/NEWS.d/next/Core and
Builtins/2024-03-12-20-31-57.gh-issue-113964.bJppzg.rst b/Misc/NEWS.d/next/Core
and Builtins/2024-03-12-20-31-57.gh-issue-113964.bJppzg.rst
new file mode 100644
index 00000000000000..ab370d4aa1baee
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and
Builtins/2024-03-12-20-31-57.gh-issue-113964.bJppzg.rst
@@ -0,0 +1,2 @@
+Starting new threads and process creation through :func:`os.fork` are now
+only prevented once all non-daemon threads exit.
diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index d75bb92757c7a4..35ea2ac306a3e6 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -946,7 +946,9 @@ subprocess_fork_exec_impl(PyObject *module, PyObject
*process_args,
Py_ssize_t fds_to_keep_len = PyTuple_GET_SIZE(py_fds_to_keep);
PyInterpreterState *interp = PyInterpreterState_Get();
- if ((preexec_fn != Py_None) && interp->finalizing) {
+ if ((preexec_fn != Py_None) &&
+ _PyInterpreterState_GetFinalizing(interp) != NULL)
+ {
PyErr_SetString(PyExc_RuntimeError,
"preexec_fn not supported at interpreter shutdown");
return NULL;
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index 568fe8375d1eb4..365f4460088aab 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -1190,7 +1190,7 @@ thread_PyThread_start_new_thread(PyObject *self, PyObject
*fargs)
"thread is not supported for isolated
subinterpreters");
return NULL;
}
- if (interp->finalizing) {
+ if (_PyInterpreterState_GetFinalizing(interp) != NULL) {
PyErr_SetString(PyExc_RuntimeError,
"can't create new thread at interpreter shutdown");
return NULL;
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index d665d069d2c4fe..9f69c792614eec 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -7663,7 +7663,7 @@ os_fork1_impl(PyObject *module)
pid_t pid;
PyInterpreterState *interp = _PyInterpreterState_GET();
- if (interp->finalizing) {
+ if (_PyInterpreterState_GetFinalizing(interp) != NULL) {
PyErr_SetString(PyExc_RuntimeError,
"can't fork at interpreter shutdown");
return NULL;
@@ -7707,7 +7707,7 @@ os_fork_impl(PyObject *module)
{
pid_t pid;
PyInterpreterState *interp = _PyInterpreterState_GET();
- if (interp->finalizing) {
+ if (_PyInterpreterState_GetFinalizing(interp) != NULL) {
PyErr_SetString(PyExc_RuntimeError,
"can't fork at interpreter shutdown");
return NULL;
@@ -8391,7 +8391,7 @@ os_forkpty_impl(PyObject *module)
pid_t pid;
PyInterpreterState *interp = _PyInterpreterState_GET();
- if (interp->finalizing) {
+ if (_PyInterpreterState_GetFinalizing(interp) != NULL) {
PyErr_SetString(PyExc_RuntimeError,
"can't fork at interpreter shutdown");
return NULL;
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 65d0842cb111e0..fc9379be02f4dc 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -516,7 +516,7 @@ unicode_check_encoding_errors(const char *encoding, const
char *errors)
/* Disable checks during Python finalization. For example, it allows to
call _PyObject_Dump() during finalization for debugging purpose. */
- if (interp->finalizing) {
+ if (_PyInterpreterState_GetFinalizing(interp) != NULL) {
return 0;
}
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