diff options
| -rw-r--r-- | Lib/test/script_helper.py | 18 | ||||
| -rw-r--r-- | Lib/test/test_io.py | 45 | ||||
| -rw-r--r-- | Lib/test/test_script_helper.py | 17 | ||||
| -rw-r--r-- | Misc/NEWS | 5 | ||||
| -rw-r--r-- | Modules/_io/bufferedio.c | 23 |
5 files changed, 94 insertions, 14 deletions
diff --git a/Lib/test/script_helper.py b/Lib/test/script_helper.py index 8743dba..7ac19bf 100644 --- a/Lib/test/script_helper.py +++ b/Lib/test/script_helper.py @@ -1,6 +1,7 @@ # Common utility functions used by various script execution tests # e.g. test_cmd_line, test_cmd_line_script and test_runpy +import collections import importlib import sys import os @@ -50,8 +51,12 @@ def interpreter_requires_environment(): return __cached_interp_requires_environment +_PythonRunResult = collections.namedtuple("_PythonRunResult", + ("rc", "out", "err")) + + # Executing the interpreter in a subprocess -def _assert_python(expected_success, *args, **env_vars): +def run_python_until_end(*args, **env_vars): env_required = interpreter_requires_environment() if '__isolated' in env_vars: isolated = env_vars.pop('__isolated') @@ -85,9 +90,14 @@ def _assert_python(expected_success, *args, **env_vars): p.stderr.close() rc = p.returncode err = strip_python_stderr(err) - if (rc and expected_success) or (not rc and not expected_success): + return _PythonRunResult(rc, out, err), cmd_line + +def _assert_python(expected_success, *args, **env_vars): + res, cmd_line = run_python_until_end(*args, **env_vars) + if (res.rc and expected_success) or (not res.rc and not expected_success): # Limit to 80 lines to ASCII characters maxlen = 80 * 100 + out, err = res.out, res.err if len(out) > maxlen: out = b'(... truncated stdout ...)' + out[-maxlen:] if len(err) > maxlen: @@ -106,10 +116,10 @@ def _assert_python(expected_success, *args, **env_vars): "---\n" "%s\n" "---" - % (rc, cmd_line, + % (res.rc, cmd_line, out, err)) - return rc, out, err + return res def assert_python_ok(*args, **env_vars): """ diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py index 9fb85f2..2d02a31 100644 --- a/Lib/test/test_io.py +++ b/Lib/test/test_io.py @@ -35,7 +35,7 @@ import weakref from collections import deque, UserList from itertools import cycle, count from test import support -from test.script_helper import assert_python_ok +from test.script_helper import assert_python_ok, run_python_until_end import codecs import io # C implementation of io @@ -3437,6 +3437,49 @@ class CMiscIOTest(MiscIOTest): b = bytearray(2) self.assertRaises(ValueError, bufio.readinto, b) + @unittest.skipUnless(threading, 'Threading required for this test.') + def check_daemon_threads_shutdown_deadlock(self, stream_name): + # Issue #23309: deadlocks at shutdown should be avoided when a + # daemon thread and the main thread both write to a file. + code = """if 1: + import sys + import time + import threading + + file = sys.{stream_name} + + def run(): + while True: + file.write('.') + file.flush() + + thread = threading.Thread(target=run) + thread.daemon = True + thread.start() + + time.sleep(0.5) + file.write('!') + file.flush() + """.format_map(locals()) + res, _ = run_python_until_end("-c", code) + err = res.err.decode() + if res.rc != 0: + # Failure: should be a fatal error + self.assertIn("Fatal Python error: could not acquire lock " + "for <_io.BufferedWriter name='<{stream_name}>'> " + "at interpreter shutdown, possibly due to " + "daemon threads".format_map(locals()), + err) + else: + self.assertFalse(err.strip('.!')) + + def test_daemon_threads_shutdown_stdout_deadlock(self): + self.check_daemon_threads_shutdown_deadlock('stdout') + + def test_daemon_threads_shutdown_stderr_deadlock(self): + self.check_daemon_threads_shutdown_deadlock('stderr') + + class PyMiscIOTest(MiscIOTest): io = pyio diff --git a/Lib/test/test_script_helper.py b/Lib/test/test_script_helper.py index 7f5d654..8694530 100644 --- a/Lib/test/test_script_helper.py +++ b/Lib/test/test_script_helper.py @@ -8,26 +8,27 @@ from unittest import mock class TestScriptHelper(unittest.TestCase): - def test_assert_python_expect_success(self): - t = script_helper._assert_python(True, '-c', 'import sys; sys.exit(0)') + + def test_assert_python_ok(self): + t = script_helper.assert_python_ok('-c', 'import sys; sys.exit(0)') self.assertEqual(0, t[0], 'return code was not 0') - def test_assert_python_expect_failure(self): + def test_assert_python_failure(self): # I didn't import the sys module so this child will fail. - rc, out, err = script_helper._assert_python(False, '-c', 'sys.exit(0)') + rc, out, err = script_helper.assert_python_failure('-c', 'sys.exit(0)') self.assertNotEqual(0, rc, 'return code should not be 0') - def test_assert_python_raises_expect_success(self): + def test_assert_python_ok_raises(self): # I didn't import the sys module so this child will fail. with self.assertRaises(AssertionError) as error_context: - script_helper._assert_python(True, '-c', 'sys.exit(0)') + script_helper.assert_python_ok('-c', 'sys.exit(0)') error_msg = str(error_context.exception) self.assertIn('command line:', error_msg) self.assertIn('sys.exit(0)', error_msg, msg='unexpected command line') - def test_assert_python_raises_expect_failure(self): + def test_assert_python_failure_raises(self): with self.assertRaises(AssertionError) as error_context: - script_helper._assert_python(False, '-c', 'import sys; sys.exit(0)') + script_helper.assert_python_failure('-c', 'import sys; sys.exit(0)') error_msg = str(error_context.exception) self.assertIn('Process return code is 0\n', error_msg) self.assertIn('import sys; sys.exit(0)', error_msg, @@ -10,6 +10,11 @@ Release date: XXX Core and Builtins ----------------- +- Issue #23309: Avoid a deadlock at shutdown if a daemon thread is aborted + while it is holding a lock to a buffered I/O object, and the main thread + tries to use the same I/O object (typically stdout or stderr). A fatal + error is emitted instead. + - Issue #22977: Fixed formatting Windows error messages on Wine. Patch by Martin Panter. diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c index ea9f533..7cf5dda 100644 --- a/Modules/_io/bufferedio.c +++ b/Modules/_io/bufferedio.c @@ -318,14 +318,35 @@ typedef struct { static int _enter_buffered_busy(buffered *self) { + int relax_locking; + PyLockStatus st; if (self->owner == PyThread_get_thread_ident()) { PyErr_Format(PyExc_RuntimeError, "reentrant call inside %R", self); return 0; } + relax_locking = (_Py_Finalizing != NULL); Py_BEGIN_ALLOW_THREADS - PyThread_acquire_lock(self->lock, 1); + if (!relax_locking) + st = PyThread_acquire_lock(self->lock, 1); + else { + /* When finalizing, we don't want a deadlock to happen with daemon + * threads abruptly shut down while they owned the lock. + * Therefore, only wait for a grace period (1 s.). + * Note that non-daemon threads have already exited here, so this + * shouldn't affect carefully written threaded I/O code. + */ + st = PyThread_acquire_lock_timed(self->lock, 1e6, 0); + } Py_END_ALLOW_THREADS + if (relax_locking && st != PY_LOCK_ACQUIRED) { + PyObject *msgobj = PyUnicode_FromFormat( + "could not acquire lock for %A at interpreter " + "shutdown, possibly due to daemon threads", + (PyObject *) self); + char *msg = PyUnicode_AsUTF8(msgobj); + Py_FatalError(msg); + } return 1; } |