From ec74d187f50a8a48f94eb37023300583fbd644cc Mon Sep 17 00:00:00 2001 From: Pablo Galindo Date: Tue, 4 Sep 2018 09:53:54 +0100 Subject: bpo-33613, test_semaphore_tracker_sigint: fix race condition (#7850) Fail `test_semaphore_tracker_sigint` if no warnings are expected and one is received. Fix race condition when the child receives SIGINT before it can register signal handlers for it. The race condition occurs when the parent calls `_semaphore_tracker.ensure_running()` (which in turn spawns the semaphore_tracker using `_posixsubprocess.fork_exec`), the child registers the signal handlers and the parent tries to kill the child. What seem to happen is that in some slow systems, the parent sends the signal to kill the child before the child protects against the signal. --- Lib/test/_test_multiprocessing.py | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) (limited to 'Lib/test/_test_multiprocessing.py') diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index 749cf8c4fd..a5509ce913 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -20,6 +20,7 @@ import logging import struct import operator import weakref +import warnings import test.support import test.support.script_helper from test import support @@ -4517,17 +4518,19 @@ class TestSemaphoreTracker(unittest.TestCase): # bpo-31310: if the semaphore tracker process has died, it should # be restarted implicitly. from multiprocessing.semaphore_tracker import _semaphore_tracker - _semaphore_tracker.ensure_running() pid = _semaphore_tracker._pid + if pid is not None: + os.kill(pid, signal.SIGKILL) + os.waitpid(pid, 0) + with warnings.catch_warnings(record=True) as all_warn: + _semaphore_tracker.ensure_running() + pid = _semaphore_tracker._pid + os.kill(pid, signum) time.sleep(1.0) # give it time to die ctx = multiprocessing.get_context("spawn") - with contextlib.ExitStack() as stack: - if should_die: - stack.enter_context(self.assertWarnsRegex( - UserWarning, - "semaphore_tracker: process died")) + with warnings.catch_warnings(record=True) as all_warn: sem = ctx.Semaphore() sem.acquire() sem.release() @@ -4537,11 +4540,23 @@ class TestSemaphoreTracker(unittest.TestCase): del sem gc.collect() self.assertIsNone(wr()) + if should_die: + self.assertEqual(len(all_warn), 1) + the_warn = all_warn[0] + issubclass(the_warn.category, UserWarning) + self.assertTrue("semaphore_tracker: process died" + in str(the_warn.message)) + else: + self.assertEqual(len(all_warn), 0) def test_semaphore_tracker_sigint(self): # Catchable signal (ignored by semaphore tracker) self.check_semaphore_tracker_death(signal.SIGINT, False) + def test_semaphore_tracker_sigterm(self): + # Catchable signal (ignored by semaphore tracker) + self.check_semaphore_tracker_death(signal.SIGTERM, False) + def test_semaphore_tracker_sigkill(self): # Uncatchable signal. self.check_semaphore_tracker_death(signal.SIGKILL, True) -- cgit v1.2.1