test_policies.py 文件源码

def test_thread_safety_during_modification(self):
        hosts = range(100)
        policy = RoundRobinPolicy()
        policy.populate(None, hosts)

        errors = []

        def check_query_plan():
            try:
                for i in xrange(100):
                    list(policy.make_query_plan())
            except Exception as exc:
                errors.append(exc)

        def host_up():
            for i in xrange(1000):
                policy.on_up(randint(0, 99))

        def host_down():
            for i in xrange(1000):
                policy.on_down(randint(0, 99))

        threads = []
        for i in range(5):
            threads.append(Thread(target=check_query_plan))
            threads.append(Thread(target=host_up))
            threads.append(Thread(target=host_down))

        # make the GIL switch after every instruction, maximizing
        # the chance of race conditions
        check = six.PY2 or '__pypy__' in sys.builtin_module_names
        if check:
            original_interval = sys.getcheckinterval()
        else:
            original_interval = sys.getswitchinterval()

        try:
            if check:
                sys.setcheckinterval(0)
            else:
                sys.setswitchinterval(0.0001)
            map(lambda t: t.start(), threads)
            map(lambda t: t.join(), threads)
        finally:
            if check:
                sys.setcheckinterval(original_interval)
            else:
                sys.setswitchinterval(original_interval)

        if errors:
            self.fail("Saw errors: %s" % (errors,))