diff options
| -rw-r--r-- | Lib/test/test_io.py | 21 | ||||
| -rw-r--r-- | Misc/NEWS | 3 | ||||
| -rw-r--r-- | Modules/_io/textio.c | 13 |
3 files changed, 33 insertions, 4 deletions
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py index edb593b23d..4288f1ba05 100644 --- a/Lib/test/test_io.py +++ b/Lib/test/test_io.py @@ -2061,6 +2061,27 @@ class TextIOWrapperTest(unittest.TestCase): self.assertEqual(f.errors, "replace") + def test_threads_write(self): + # Issue6750: concurrent writes could duplicate data + event = threading.Event() + with self.open(support.TESTFN, "w", buffering=1) as f: + def run(n): + text = "Thread%03d\n" % n + event.wait() + f.write(text) + threads = [threading.Thread(target=lambda n=x: run(n)) + for x in range(20)] + for t in threads: + t.start() + time.sleep(0.02) + event.set() + for t in threads: + t.join() + with self.open(support.TESTFN) as f: + content = f.read() + for n in range(20): + self.assertEquals(content.count("Thread%03d\n" % n), 1) + class CTextIOWrapperTest(TextIOWrapperTest): def test_initialization(self): @@ -12,6 +12,9 @@ What's New in Python 2.7 alpha 1 Core and Builtins ----------------- +- Issue #6750: A text file opened with io.open() could duplicate its output + when writing from multiple threads at the same time. + - Issue #6704: Improve the col_offset in AST for "for" statements with a target of tuple unpacking. diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c index c129303a3d..3b627f2245 100644 --- a/Modules/_io/textio.c +++ b/Modules/_io/textio.c @@ -1189,11 +1189,18 @@ findchar(const Py_UNICODE *s, Py_ssize_t size, Py_UNICODE ch) static int _textiowrapper_writeflush(textio *self) { - PyObject *b, *ret; + PyObject *pending, *b, *ret; if (self->pending_bytes == NULL) return 0; - b = _PyBytes_Join(_PyIO_empty_bytes, self->pending_bytes); + + pending = self->pending_bytes; + Py_INCREF(pending); + self->pending_bytes_count = 0; + Py_CLEAR(self->pending_bytes); + + b = _PyBytes_Join(_PyIO_empty_bytes, pending); + Py_DECREF(pending); if (b == NULL) return -1; ret = PyObject_CallMethodObjArgs(self->buffer, @@ -1202,8 +1209,6 @@ _textiowrapper_writeflush(textio *self) if (ret == NULL) return -1; Py_DECREF(ret); - Py_CLEAR(self->pending_bytes); - self->pending_bytes_count = 0; return 0; } |