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bpo-37076: _thread.start_new_thread() calls _PyErr_WriteUnraisableMsg() #13617

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Merged
vstinner merged 4 commits into from
May 29, 2019
Merged

bpo-37076: _thread.start_new_thread() calls _PyErr_WriteUnraisableMsg() #13617

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8df3fc2
bpo-37076: _thread.start_new_thread() calls _PyErr_WriteUnraisableMsg()
vstinner May 28, 2019
c92ed35
Update start_new_thread() doc
vstinner May 28, 2019
d1b3a5e
Fix typo in doc
vstinner May 28, 2019
029db0e
Clarify doc
vstinner May 29, 2019
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18 changes: 18 additions & 0 deletions Lib/test/test_thread.py
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Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,24 @@ def mywrite(self, *args):
started.acquire()
self.assertIn("Traceback", stderr.getvalue())

def test_unraisable_exception(self):
def task():
started.release()
raise ValueError("task failed")

started = thread.allocate_lock()
with support.catch_unraisable_exception() as cm:
with support.wait_threads_exit():
started.acquire()
thread.start_new_thread(task, ())
started.acquire()

self.assertEqual(str(cm.unraisable.exc_value), "task failed")
self.assertIs(cm.unraisable.object, task)
self.assertEqual(cm.unraisable.err_msg,
"Exception ignored in thread started by")
self.assertIsNotNone(cm.unraisable.exc_traceback)


class Barrier:
def __init__(self, num_threads):
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2019-05-28-12-17-10.bpo-37076.Bk2xOs.rst
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@@ -0,0 +1,3 @@
:func:`_thread.start_new_thread` now logs uncaught exception raised by the
function using :func:`sys.unraisablehook`, rather than :func:`sys.excepthook`,
so the hook gets access to the function which raised the exception.
17 changes: 3 additions & 14 deletions Modules/_threadmodule.c
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Expand Up @@ -1004,23 +1004,12 @@ t_bootstrap(void *boot_raw)
if (PyErr_ExceptionMatches(PyExc_SystemExit))
PyErr_Clear();
else {
PyObject *file;
PyObject *exc, *value, *tb;
PySys_WriteStderr(
"Unhandled exception in thread started by ");
PyErr_Fetch(&exc, &value, &tb);
file = _PySys_GetObjectId(&PyId_stderr);
if (file != NULL && file != Py_None)
PyFile_WriteObject(boot->func, file, 0);
else
PyObject_Print(boot->func, stderr, 0);
PySys_WriteStderr("\n");
PyErr_Restore(exc, value, tb);
PyErr_PrintEx(0);
_PyErr_WriteUnraisableMsg("in thread started by", boot->func);
}
}
else
else {
Py_DECREF(res);
}
Py_DECREF(boot->func);
Py_DECREF(boot->args);
Py_XDECREF(boot->keyw);
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