#6750: TextIOWrapped could duplicate output when several threads write to it.
this affect text files opened with io.open(), and the print() function of py3k
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index edb593b..4288f1b 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -2061,6 +2061,27 @@
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):