diff options
Diffstat (limited to 'Lib')
| -rw-r--r-- | Lib/test/test_threading.py | 92 | ||||
| -rw-r--r-- | Lib/threading.py | 155 |
2 files changed, 195 insertions, 52 deletions
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py index 3bfd6fa..8c8cc12 100644 --- a/Lib/test/test_threading.py +++ b/Lib/test/test_threading.py @@ -1112,6 +1112,98 @@ class ThreadingExceptionTests(BaseTestCase): # explicitly break the reference cycle to not leak a dangling thread thread.exc = None + +class ThreadRunFail(threading.Thread): + def run(self): + raise ValueError("run failed") + + +class ExceptHookTests(BaseTestCase): + def test_excepthook(self): + with support.captured_output("stderr") as stderr: + thread = ThreadRunFail(name="excepthook thread") + thread.start() + thread.join() + + stderr = stderr.getvalue().strip() + self.assertIn(f'Exception in thread {thread.name}:\n', stderr) + self.assertIn('Traceback (most recent call last):\n', stderr) + self.assertIn(' raise ValueError("run failed")', stderr) + self.assertIn('ValueError: run failed', stderr) + + @support.cpython_only + def test_excepthook_thread_None(self): + # threading.excepthook called with thread=None: log the thread + # identifier in this case. + with support.captured_output("stderr") as stderr: + try: + raise ValueError("bug") + except Exception as exc: + args = threading.ExceptHookArgs([*sys.exc_info(), None]) + threading.excepthook(args) + + stderr = stderr.getvalue().strip() + self.assertIn(f'Exception in thread {threading.get_ident()}:\n', stderr) + self.assertIn('Traceback (most recent call last):\n', stderr) + self.assertIn(' raise ValueError("bug")', stderr) + self.assertIn('ValueError: bug', stderr) + + def test_system_exit(self): + class ThreadExit(threading.Thread): + def run(self): + sys.exit(1) + + # threading.excepthook() silently ignores SystemExit + with support.captured_output("stderr") as stderr: + thread = ThreadExit() + thread.start() + thread.join() + + self.assertEqual(stderr.getvalue(), '') + + def test_custom_excepthook(self): + args = None + + def hook(hook_args): + nonlocal args + args = hook_args + + try: + with support.swap_attr(threading, 'excepthook', hook): + thread = ThreadRunFail() + thread.start() + thread.join() + + self.assertEqual(args.exc_type, ValueError) + self.assertEqual(str(args.exc_value), 'run failed') + self.assertEqual(args.exc_traceback, args.exc_value.__traceback__) + self.assertIs(args.thread, thread) + finally: + # Break reference cycle + args = None + + def test_custom_excepthook_fail(self): + def threading_hook(args): + raise ValueError("threading_hook failed") + + err_str = None + + def sys_hook(exc_type, exc_value, exc_traceback): + nonlocal err_str + err_str = str(exc_value) + + with support.swap_attr(threading, 'excepthook', threading_hook), \ + support.swap_attr(sys, 'excepthook', sys_hook), \ + support.captured_output('stderr') as stderr: + thread = ThreadRunFail() + thread.start() + thread.join() + + self.assertEqual(stderr.getvalue(), + 'Exception in threading.excepthook:\n') + self.assertEqual(err_str, 'threading_hook failed') + + class TimerTests(BaseTestCase): def setUp(self): diff --git a/Lib/threading.py b/Lib/threading.py index 77a2bae..3d197ee 100644 --- a/Lib/threading.py +++ b/Lib/threading.py @@ -5,7 +5,6 @@ import sys as _sys import _thread from time import monotonic as _time -from traceback import format_exc as _format_exc from _weakrefset import WeakSet from itertools import islice as _islice, count as _count try: @@ -27,7 +26,8 @@ __all__ = ['get_ident', 'active_count', 'Condition', 'current_thread', 'enumerate', 'main_thread', 'TIMEOUT_MAX', 'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread', 'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError', - 'setprofile', 'settrace', 'local', 'stack_size'] + 'setprofile', 'settrace', 'local', 'stack_size', + 'excepthook', 'ExceptHookArgs'] # Rename some stuff so "from threading import *" is safe _start_new_thread = _thread.start_new_thread @@ -752,14 +752,6 @@ class Thread: """ _initialized = False - # Need to store a reference to sys.exc_info for printing - # out exceptions when a thread tries to use a global var. during interp. - # shutdown and thus raises an exception about trying to perform some - # operation on/with a NoneType - _exc_info = _sys.exc_info - # Keep sys.exc_clear too to clear the exception just before - # allowing .join() to return. - #XXX __exc_clear = _sys.exc_clear def __init__(self, group=None, target=None, name=None, args=(), kwargs=None, *, daemon=None): @@ -802,9 +794,9 @@ class Thread: self._started = Event() self._is_stopped = False self._initialized = True - # sys.stderr is not stored in the class like - # sys.exc_info since it can be changed between instances + # Copy of sys.stderr used by self._invoke_excepthook() self._stderr = _sys.stderr + self._invoke_excepthook = _make_invoke_excepthook() # For debugging and _after_fork() _dangling.add(self) @@ -929,47 +921,8 @@ class Thread: try: self.run() - except SystemExit: - pass except: - # If sys.stderr is no more (most likely from interpreter - # shutdown) use self._stderr. Otherwise still use sys (as in - # _sys) in case sys.stderr was redefined since the creation of - # self. - if _sys and _sys.stderr is not None: - print("Exception in thread %s:\n%s" % - (self.name, _format_exc()), file=_sys.stderr) - elif self._stderr is not None: - # Do the best job possible w/o a huge amt. of code to - # approximate a traceback (code ideas from - # Lib/traceback.py) - exc_type, exc_value, exc_tb = self._exc_info() - try: - print(( - "Exception in thread " + self.name + - " (most likely raised during interpreter shutdown):"), file=self._stderr) - print(( - "Traceback (most recent call last):"), file=self._stderr) - while exc_tb: - print(( - ' File "%s", line %s, in %s' % - (exc_tb.tb_frame.f_code.co_filename, - exc_tb.tb_lineno, - exc_tb.tb_frame.f_code.co_name)), file=self._stderr) - exc_tb = exc_tb.tb_next - print(("%s: %s" % (exc_type, exc_value)), file=self._stderr) - self._stderr.flush() - # Make sure that exc_tb gets deleted since it is a memory - # hog; deleting everything else is just for thoroughness - finally: - del exc_type, exc_value, exc_tb - finally: - # Prevent a race in - # test_threading.test_no_refcycle_through_target when - # the exception keeps the target alive past when we - # assert that it's dead. - #XXX self._exc_clear() - pass + self._invoke_excepthook(self) finally: with _active_limbo_lock: try: @@ -1163,6 +1116,104 @@ class Thread: def setName(self, name): self.name = name + +try: + from _thread import (_excepthook as excepthook, + _ExceptHookArgs as ExceptHookArgs) +except ImportError: + # Simple Python implementation if _thread._excepthook() is not available + from traceback import print_exception as _print_exception + from collections import namedtuple + + _ExceptHookArgs = namedtuple( + 'ExceptHookArgs', + 'exc_type exc_value exc_traceback thread') + + def ExceptHookArgs(args): + return _ExceptHookArgs(*args) + + def excepthook(args, /): + """ + Handle uncaught Thread.run() exception. + """ + if args.exc_type == SystemExit: + # silently ignore SystemExit + return + + if _sys is not None and _sys.stderr is not None: + stderr = _sys.stderr + elif args.thread is not None: + stderr = args.thread._stderr + if stderr is None: + # do nothing if sys.stderr is None and sys.stderr was None + # when the thread was created + return + else: + # do nothing if sys.stderr is None and args.thread is None + return + + if args.thread is not None: + name = args.thread.name + else: + name = get_ident() + print(f"Exception in thread {name}:", + file=stderr, flush=True) + _print_exception(args.exc_type, args.exc_value, args.exc_traceback, + file=stderr) + stderr.flush() + + +def _make_invoke_excepthook(): + # Create a local namespace to ensure that variables remain alive + # when _invoke_excepthook() is called, even if it is called late during + # Python shutdown. It is mostly needed for daemon threads. + + old_excepthook = excepthook + old_sys_excepthook = _sys.excepthook + if old_excepthook is None: + raise RuntimeError("threading.excepthook is None") + if old_sys_excepthook is None: + raise RuntimeError("sys.excepthook is None") + + sys_exc_info = _sys.exc_info + local_print = print + local_sys = _sys + + def invoke_excepthook(thread): + global excepthook + try: + hook = excepthook + if hook is None: + hook = old_excepthook + + args = ExceptHookArgs([*sys_exc_info(), thread]) + + hook(args) + except Exception as exc: + exc.__suppress_context__ = True + del exc + + if local_sys is not None and local_sys.stderr is not None: + stderr = local_sys.stderr + else: + stderr = thread._stderr + + local_print("Exception in threading.excepthook:", + file=stderr, flush=True) + + if local_sys is not None and local_sys.excepthook is not None: + sys_excepthook = local_sys.excepthook + else: + sys_excepthook = old_sys_excepthook + + sys_excepthook(*sys_exc_info()) + finally: + # Break reference cycle (exception stored in a variable) + args = None + + return invoke_excepthook + + # The timer class was contributed by Itamar Shtull-Trauring class Timer(Thread): |