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author | Antoine Pitrou <pitrou@free.fr> | 2018-03-11 18:21:38 (GMT) |
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committer | GitHub <noreply@github.com> | 2018-03-11 18:21:38 (GMT) |
commit | e756f66c83786ee82f5f7d45931ae50a6931dd7f (patch) | |
tree | f3d6b9bd7d6319fc3149841bb7498e326d9fe7c9 | |
parent | 9fb84157595a385f15799e5d0729c1e1b0ba9d38 (diff) | |
download | cpython-e756f66c83786ee82f5f7d45931ae50a6931dd7f.zip cpython-e756f66c83786ee82f5f7d45931ae50a6931dd7f.tar.gz cpython-e756f66c83786ee82f5f7d45931ae50a6931dd7f.tar.bz2 |
bpo-31804: Fix multiprocessing.Process with broken standard streams (#6079)
In some conditions the standard streams will be None or closed in the child process (for example if using "pythonw" instead of "python" on Windows). Avoid failing with a non-0 exit code in those conditions.
Report and initial patch by poxthegreat.
-rw-r--r-- | Lib/multiprocessing/popen_fork.py | 9 | ||||
-rw-r--r-- | Lib/multiprocessing/process.py | 3 | ||||
-rw-r--r-- | Lib/multiprocessing/util.py | 14 | ||||
-rw-r--r-- | Lib/test/_test_multiprocessing.py | 31 | ||||
-rw-r--r-- | Misc/NEWS.d/next/Library/2018-03-11-19-03-52.bpo-31804.i8KUMp.rst | 2 |
5 files changed, 47 insertions, 12 deletions
diff --git a/Lib/multiprocessing/popen_fork.py b/Lib/multiprocessing/popen_fork.py index b0fc013..008b97b 100644 --- a/Lib/multiprocessing/popen_fork.py +++ b/Lib/multiprocessing/popen_fork.py @@ -14,14 +14,7 @@ class Popen(object): method = 'fork' def __init__(self, process_obj): - try: - sys.stdout.flush() - except (AttributeError, ValueError): - pass - try: - sys.stderr.flush() - except (AttributeError, ValueError): - pass + util._flush_std_streams() self.returncode = None self.finalizer = None self._launch(process_obj) diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py index 8fff3e1..cd592d0 100644 --- a/Lib/multiprocessing/process.py +++ b/Lib/multiprocessing/process.py @@ -314,8 +314,7 @@ class BaseProcess(object): finally: threading._shutdown() util.info('process exiting with exitcode %d' % exitcode) - sys.stdout.flush() - sys.stderr.flush() + util._flush_std_streams() return exitcode diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py index f0827f0..0c4eb24 100644 --- a/Lib/multiprocessing/util.py +++ b/Lib/multiprocessing/util.py @@ -392,6 +392,20 @@ def _close_stdin(): pass # +# Flush standard streams, if any +# + +def _flush_std_streams(): + try: + sys.stdout.flush() + except (AttributeError, ValueError): + pass + try: + sys.stderr.flush() + except (AttributeError, ValueError): + pass + +# # Start a program with only specified fds kept open # diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index 1e497a5..940fe58 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -584,10 +584,19 @@ class _TestProcess(BaseTestCase): self.assertTrue(evt.is_set()) @classmethod - def _test_error_on_stdio_flush(self, evt): + def _test_error_on_stdio_flush(self, evt, break_std_streams={}): + for stream_name, action in break_std_streams.items(): + if action == 'close': + stream = io.StringIO() + stream.close() + else: + assert action == 'remove' + stream = None + setattr(sys, stream_name, None) evt.set() - def test_error_on_stdio_flush(self): + def test_error_on_stdio_flush_1(self): + # Check that Process works with broken standard streams streams = [io.StringIO(), None] streams[0].close() for stream_name in ('stdout', 'stderr'): @@ -601,6 +610,24 @@ class _TestProcess(BaseTestCase): proc.start() proc.join() self.assertTrue(evt.is_set()) + self.assertEqual(proc.exitcode, 0) + finally: + setattr(sys, stream_name, old_stream) + + def test_error_on_stdio_flush_2(self): + # Same as test_error_on_stdio_flush_1(), but standard streams are + # broken by the child process + for stream_name in ('stdout', 'stderr'): + for action in ('close', 'remove'): + old_stream = getattr(sys, stream_name) + try: + evt = self.Event() + proc = self.Process(target=self._test_error_on_stdio_flush, + args=(evt, {stream_name: action})) + proc.start() + proc.join() + self.assertTrue(evt.is_set()) + self.assertEqual(proc.exitcode, 0) finally: setattr(sys, stream_name, old_stream) diff --git a/Misc/NEWS.d/next/Library/2018-03-11-19-03-52.bpo-31804.i8KUMp.rst b/Misc/NEWS.d/next/Library/2018-03-11-19-03-52.bpo-31804.i8KUMp.rst new file mode 100644 index 0000000..7fcede2 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2018-03-11-19-03-52.bpo-31804.i8KUMp.rst @@ -0,0 +1,2 @@ +Avoid failing in multiprocessing.Process if the standard streams are closed +or None at exit. |