diff options
| author | Gregory P. Smith <greg@krypto.org> | 2014-04-23 07:27:17 (GMT) |
|---|---|---|
| committer | Gregory P. Smith <greg@krypto.org> | 2014-04-23 07:27:17 (GMT) |
| commit | d65ba51e245ffdd155bc1e7b8884fc943048111f (patch) | |
| tree | f9cfcc72574b93fc268e08924ac0510a4318d376 /Lib/test | |
| parent | 9e599673b4434a66ec44866e1ad81c89d9950b87 (diff) | |
| download | cpython-d65ba51e245ffdd155bc1e7b8884fc943048111f.zip cpython-d65ba51e245ffdd155bc1e7b8884fc943048111f.tar.gz cpython-d65ba51e245ffdd155bc1e7b8884fc943048111f.tar.bz2 | |
subprocess's Popen.wait() is now thread safe so that multiple threads
may be calling wait() or poll() on a Popen instance at the same time
without losing the Popen.returncode value. Fixes issue #21291.
Diffstat (limited to 'Lib/test')
| -rw-r--r-- | Lib/test/test_subprocess.py | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py index 46e012d..c57b899 100644 --- a/Lib/test/test_subprocess.py +++ b/Lib/test/test_subprocess.py @@ -1052,6 +1052,54 @@ class ProcessTestCase(BaseTestCase): if exc is not None: raise exc + @unittest.skipIf(threading is None, "threading required") + def test_threadsafe_wait(self): + """Issue21291: Popen.wait() needs to be threadsafe for returncode.""" + proc = subprocess.Popen([sys.executable, '-c', + 'import time; time.sleep(12)']) + self.assertEqual(proc.returncode, None) + results = [] + + def kill_proc_timer_thread(): + results.append(('thread-start-poll-result', proc.poll())) + # terminate it from the thread and wait for the result. + proc.kill() + proc.wait() + results.append(('thread-after-kill-and-wait', proc.returncode)) + # this wait should be a no-op given the above. + proc.wait() + results.append(('thread-after-second-wait', proc.returncode)) + + # This is a timing sensitive test, the failure mode is + # triggered when both the main thread and this thread are in + # the wait() call at once. The delay here is to allow the + # main thread to most likely be blocked in its wait() call. + t = threading.Timer(0.2, kill_proc_timer_thread) + t.start() + + # Wait for the process to finish; the thread should kill it + # long before it finishes on its own. Supplying a timeout + # triggers a different code path for better coverage. + proc.wait(timeout=20) + # Should be -9 because of the proc.kill() from the thread. + self.assertEqual(proc.returncode, -9, + msg="unexpected result in wait from main thread") + + # This should be a no-op with no change in returncode. + proc.wait() + self.assertEqual(proc.returncode, -9, + msg="unexpected result in second main wait.") + + t.join() + # Ensure that all of the thread results are as expected. + # When a race condition occurs in wait(), the returncode could + # be set by the wrong thread that doesn't actually have it + # leading to an incorrect value. + self.assertEqual([('thread-start-poll-result', None), + ('thread-after-kill-and-wait', -9), + ('thread-after-second-wait', -9)], + results) + def test_issue8780(self): # Ensure that stdout is inherited from the parent # if stdout=PIPE is not used |