[Python-checkins] cpython (3.2): prevent writing to stderr from messing up the exception state (closes #14474)

Mon Apr 2 17:28:56 CEST 2012

http://hg.python.org/cpython/rev/60ad83716733
changeset: 76068:60ad83716733
branch: 3.2
parent: 76059:d746ffc34e0f
user: Benjamin Peterson <benjamin at python.org>
date: Mon Apr 02 11:15:17 2012 -0400
summary:
 prevent writing to stderr from messing up the exception state (closes #14474)
files:
 Lib/test/test_thread.py | 24 ++++++++++++++++++++++++
 Misc/NEWS | 3 +++
 Modules/_threadmodule.c | 3 +++
 3 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/Lib/test/test_thread.py b/Lib/test/test_thread.py
--- a/Lib/test/test_thread.py
+++ b/Lib/test/test_thread.py
@@ -128,6 +128,30 @@
 time.sleep(0.01)
 self.assertEqual(thread._count(), orig)
 
+ def test_save_exception_state_on_error(self):
+ # See issue #14474
+ def task():
+ started.release()
+ sys.stderr = stderr
+ raise SyntaxError
+ def mywrite(self, *args):
+ try:
+ raise ValueError
+ except ValueError:
+ pass
+ real_write(self, *args)
+ c = thread._count()
+ started = thread.allocate_lock()
+ with support.captured_output("stderr") as stderr:
+ real_write = stderr.write
+ stderr.write = mywrite
+ started.acquire()
+ thread.start_new_thread(task, ())
+ started.acquire()
+ while thread._count() > c:
+ pass
+ self.assertIn("Traceback", stderr.getvalue())
+
 
 class Barrier:
 def __init__(self, num_threads):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #14474: Save and restore exception state in thread.start_new_thread()
+ while writing error message if the thread leaves a unhandled exception.
+
 - Issue #13019: Fix potential reference leaks in bytearray.extend(). Patch
 by Suman Saha.
 
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -994,14 +994,17 @@
 PyErr_Clear();
 else {
 PyObject *file;
+ PyObject *exc, *value, *tb;
 PySys_WriteStderr(
 "Unhandled exception in thread started by ");
+ PyErr_Fetch(&exc, &value, &tb);
 file = PySys_GetObject("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);
 }
 }
-- 
Repository URL: http://hg.python.org/cpython
