Python signal.alarm() Examples

def run(self, address, timeout_seconds):
        self.jitter.init_run(address)

        try:
            signal.alarm(timeout_seconds)
            self.jitter.continue_run()
        except (AssertionError, RuntimeError, ValueError,
                KeyError, IndexError, TimeoutException) as _:
            return False
        except Exception as error:
            self.logger.exception(error)
            return False
        finally:
            signal.alarm(0)

        return True 

def run(self):
        """
        Run guest main thread
        """
        global virt
        global exiting
        virt = VirtioGuestPosix()
        slave = Thread(target=worker, args=(virt,))
        slave.start()
        signal.signal(signal.SIGUSR1, sigusr_handler)
        signal.signal(signal.SIGALRM, sigusr_handler)
        while not exiting:
            signal.alarm(1)
            signal.pause()
            catch = virt.catching_signal()
            if catch:
                signal.signal(signal.SIGIO, virt)
            elif catch is False:
                signal.signal(signal.SIGIO, signal.SIG_DFL)
            if catch is not None:
                virt.use_config.set()
        print("PASS: guest_exit")
        sys.exit(0) 

def test_signals(self):
        signalled_all.acquire()
        self.spawnSignallingThread()
        signalled_all.acquire()
        # the signals that we asked the kernel to send
        # will come back, but we don't know when.
        # (it might even be after the thread exits
        # and might be out of order.)  If we haven't seen
        # the signals yet, send yet another signal and
        # wait for it return.
        if signal_blackboard[signal.SIGUSR1]['tripped'] == 0 \
           or signal_blackboard[signal.SIGUSR2]['tripped'] == 0:
            signal.alarm(1)
            signal.pause()
            signal.alarm(0)

        self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped'], 1)
        self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped_by'],
                           thread.get_ident())
        self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped'], 1)
        self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped_by'],
                           thread.get_ident())
        signalled_all.release() 

def check_interrupted_read_retry(self, decode, **fdopen_kwargs):
        """Check that a buffered read, when it gets interrupted (either
        returning a partial result or EINTR), properly invokes the signal
        handler and retries if the latter returned successfully."""
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        def alarm_handler(sig, frame):
            os.write(w, b"bar")
        signal.signal(signal.SIGALRM, alarm_handler)
        try:
            rio = self.io.open(r, **fdopen_kwargs)
            os.write(w, b"foo")
            signal.alarm(1)
            # Expected behaviour:
            # - first raw read() returns partial b"foo"
            # - second raw read() returns EINTR
            # - third raw read() returns b"bar"
            self.assertEqual(decode(rio.read(6)), "foobar")
        finally:
            rio.close()
            os.close(w)
            os.close(r) 

def __init__(cls, name, bases, attrs):
            super(RMParserType, cls).__init__(name, bases, attrs)
            if not hasattr(cls, "parsers"):
                cls.parsers = []
            else:
                cls.registerParser(cls)

            # Add timeout to perform function
            if hasattr(cls, "perform"):
                def timedPerform(self):
                    global USE_THREADING__
                    if not USE_THREADING__:
                        seconds = 10 * 60
                        _old_handler = signal.signal(signal.SIGALRM, _handle_timeout)
                        signal.alarm(seconds)
                    try:
                        result = attrs["perform"](self)
                    except RMTimeoutError, e:
                        log.error("*** Timeout occurred while running parser %s" % self.parserName)
                        log.exception(e)
                        return None
                    finally: 

def timeout(seconds=10, error_message=os.strerror(errno.ETIME)):
    def decorator(func):
        def _handle_timeout(signum, frame):
            raise TimeoutError(error_message)

        def wrapper(*args, **kwargs):
            signal.signal(signal.SIGALRM, _handle_timeout)
            signal.alarm(seconds)
            try:
                result = func(*args, **kwargs)
            finally:
                signal.alarm(0)
            return result

        return wraps(func)(wrapper)

    return decorator 

def timeout(timeout_time, default):
        '''
        Decorate a method so it is required to execute in a given time period,
        or return a default value.
        '''
        def timeout_function(f):
            def f2(*args):
                def timeout_handler(signum, frame):
                    raise MethodTimer.DecoratorTimeout()

                old_handler = signal.signal(signal.SIGALRM, timeout_handler)
                # triger alarm in timeout_time seconds
                signal.alarm(timeout_time)
                try:
                    retval = f(*args)
                except MethodTimer.DecoratorTimeout:
                    return default
                finally:
                    signal.signal(signal.SIGALRM, old_handler)
                signal.alarm(0)
                return retval
            return f2
        return timeout_function 

def timeout(seconds=0, minutes=0, hours=0):
    """
    Add a signal-based timeout to any block of code.
    If multiple time units are specified, they will be added together to determine time limit.
    Usage:
    with timeout(seconds=5):
        my_slow_function(...)
    Args:
        - seconds: The time limit, in seconds.
        - minutes: The time limit, in minutes.
        - hours: The time limit, in hours.
    """

    limit = seconds + 60 * minutes + 3600 * hours

    def handler(signum, frame):
        raise TimeoutError('timed out after {} seconds'.format(limit))

    try:
        signal.signal(signal.SIGALRM, handler)
        signal.alarm(limit)

        yield
    finally:
        signal.alarm(0) 

def test_wakeup_fd_early(self):
        import select

        signal.alarm(1)
        try:
            before_time = time.time()
            # We attempt to get a signal during the sleep,
            # before select is called
            time.sleep(self.TIMEOUT_FULL)
            mid_time = time.time()
        finally:
            signal.alarm(0)

        self.assertTrue(mid_time - before_time < self.TIMEOUT_HALF)
        select.select([self.read], [], [], self.TIMEOUT_FULL)
        after_time = time.time()
        self.assertTrue(after_time - mid_time < self.TIMEOUT_HALF) 

def check_interrupted_read_retry(self, decode, **fdopen_kwargs):
        """Check that a buffered read, when it gets interrupted (either
        returning a partial result or EINTR), properly invokes the signal
        handler and retries if the latter returned successfully."""
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        def alarm_handler(sig, frame):
            os.write(w, b"bar")
        signal.signal(signal.SIGALRM, alarm_handler)
        try:
            rio = self.io.open(r, **fdopen_kwargs)
            os.write(w, b"foo")
            signal.alarm(1)
            # Expected behaviour:
            # - first raw read() returns partial b"foo"
            # - second raw read() returns EINTR
            # - third raw read() returns b"bar"
            self.assertEqual(decode(rio.read(6)), "foobar")
        finally:
            signal.alarm(0)
            rio.close()
            os.close(w)
            os.close(r) 

def test_communicate_eintr(self):
        # Issue #12493: communicate() should handle EINTR
        def handler(signum, frame):
            pass
        old_handler = signal.signal(signal.SIGALRM, handler)
        self.addCleanup(signal.signal, signal.SIGALRM, old_handler)

        # the process is running for 2 seconds
        args = [sys.executable, "-c", 'import time; time.sleep(2)']
        for stream in ('stdout', 'stderr'):
            kw = {stream: subprocess.PIPE}
            with subprocess.Popen(args, **kw) as process:
                signal.alarm(1)
                try:
                    # communicate() will be interrupted by SIGALRM
                    process.communicate()
                finally:
                    signal.alarm(0) 

def timeout(seconds=0, minutes=0, hours=0):
    """Add a signal-based timeout to any block of code.
    If multiple time units are specified, they will be added together to determine time limit.
    Usage:
    with timeout(seconds=5):
        my_slow_function(...)
    Args:
        - seconds: The time limit, in seconds.
        - minutes: The time limit, in minutes.
        - hours: The time limit, in hours.
    """

    limit = seconds + 60 * minutes + 3600 * hours

    def handler(signum, frame):
        raise TimeoutError('timed out after {} seconds'.format(limit))

    try:
        signal.signal(signal.SIGALRM, handler)
        signal.alarm(limit)

        yield
    finally:
        signal.alarm(0) 

def check_interrupted_read_retry(self, decode, **fdopen_kwargs):
        """Check that a buffered read, when it gets interrupted (either
        returning a partial result or EINTR), properly invokes the signal
        handler and retries if the latter returned successfully."""
        r, w = os.pipe()
        fdopen_kwargs["closefd"] = False
        def alarm_handler(sig, frame):
            os.write(w, b"bar")
        signal.signal(signal.SIGALRM, alarm_handler)
        try:
            rio = self.io.open(r, **fdopen_kwargs)
            os.write(w, b"foo")
            signal.alarm(1)
            # Expected behaviour:
            # - first raw read() returns partial b"foo"
            # - second raw read() returns EINTR
            # - third raw read() returns b"bar"
            self.assertEqual(decode(rio.read(6)), "foobar")
        finally:
            rio.close()
            os.close(w)
            os.close(r) 

def test_wakeup_fd_during(self):
        import select

        signal.alarm(1)
        before_time = time.time()
        # We attempt to get a signal during the select call
        self.assertRaises(select.error, select.select,
            [self.read], [], [], self.TIMEOUT_FULL)
        after_time = time.time()
        self.assertTrue(after_time - before_time < self.TIMEOUT_HALF) 

def time_limit(seconds):
    def signal_handler(signum, frame):
        raise TimeoutException, "Timed out!"

    signal.signal(signal.SIGALRM, signal_handler)
    signal.alarm(seconds)
    try:
        yield
    finally:
        signal.alarm(0)


###########################################################
# Similarity calculation
########################################################### 

def __exit__(self, *args):
        signal.alarm(0)    # disable alarm 

def test_wakeup_fd_early(self):
        import select

        signal.alarm(1)
        before_time = time.time()
        # We attempt to get a signal during the sleep,
        # before select is called
        time.sleep(self.TIMEOUT_FULL)
        mid_time = time.time()
        self.assertTrue(mid_time - before_time < self.TIMEOUT_HALF)
        select.select([self.read], [], [], self.TIMEOUT_FULL)
        after_time = time.time()
        self.assertTrue(after_time - mid_time < self.TIMEOUT_HALF) 

def __enter__(self):
        signal.signal(signal.SIGALRM, self.raise_timeout)
        signal.alarm(self.sec) 

def test_retry_term(self):
        push = self.socket(zmq.PUSH)
        push.linger = self.timeout_ms
        push.connect('tcp://127.0.0.1:5555')
        push.send(b('ping'))
        time.sleep(0.1)
        self.alarm()
        self.context.destroy()
        assert self.timer_fired
        assert self.context.closed 

def test_wakeup_fd_during(self):
        import select

        signal.alarm(1)
        before_time = time.time()
        # We attempt to get a signal during the select call
        self.assertRaises(select.error, select.select,
            [self.read], [], [], self.TIMEOUT_FULL)
        after_time = time.time()
        self.assertTrue(after_time - before_time < self.TIMEOUT_HALF) 

def test_retry_poll(self):
        x, y = self.create_bound_pair()
        poller = zmq.Poller()
        poller.register(x, zmq.POLLIN)
        self.alarm()
        def send():
            time.sleep(2 * self.signal_delay)
            y.send(b('ping'))
        t = Thread(target=send)
        t.start()
        evts = dict(poller.poll(2 * self.timeout_ms))
        t.join()
        assert x in evts
        assert self.timer_fired
        x.recv() 

def test_retry_send(self):
        push = self.socket(zmq.PUSH)
        push.sndtimeo = self.timeout_ms
        self.alarm()
        self.assertRaises(zmq.Again, push.send, b('buf'))
        assert self.timer_fired 

def test_retry_recv(self):
        pull = self.socket(zmq.PULL)
        pull.rcvtimeo = self.timeout_ms
        self.alarm()
        self.assertRaises(zmq.Again, pull.recv)
        assert self.timer_fired 

def check_interrupted_write(self, item, bytes, **fdopen_kwargs):
        """Check that a partial write, when it gets interrupted, properly
        invokes the signal handler, and bubbles up the exception raised
        in the latter."""
        read_results = []
        def _read():
            s = os.read(r, 1)
            read_results.append(s)
        t = threading.Thread(target=_read)
        t.daemon = True
        r, w = os.pipe()
        try:
            wio = self.io.open(w, **fdopen_kwargs)
            t.start()
            signal.alarm(1)
            # Fill the pipe enough that the write will be blocking.
            # It will be interrupted by the timer armed above.  Since the
            # other thread has read one byte, the low-level write will
            # return with a successful (partial) result rather than an EINTR.
            # The buffered IO layer must check for pending signal
            # handlers, which in this case will invoke alarm_interrupt().
            self.assertRaises(ZeroDivisionError,
                        wio.write, item * (support.PIPE_MAX_SIZE // len(item) + 1))
            t.join()
            # We got one byte, get another one and check that it isn't a
            # repeat of the first one.
            read_results.append(os.read(r, 1))
            self.assertEqual(read_results, [bytes[0:1], bytes[1:2]])
        finally:
            os.close(w)
            os.close(r)
            # This is deliberate. If we didn't close the file descriptor
            # before closing wio, wio would try to flush its internal
            # buffer, and block again.
            try:
                wio.close()
            except IOError as e:
                if e.errno != errno.EBADF:
                    raise 

def alarm(self, t=None):
        """start a timer to fire only once
        
        like signal.alarm, but with better resolution than integer seconds.
        """
        if not hasattr(signal, 'setitimer'):
            raise SkipTest('EINTR tests require setitimer')
        if t is None:
            t = self.signal_delay
        self.timer_fired = False
        self.orig_handler = signal.signal(signal.SIGALRM, self.stop_timer)
        # signal_period ignored, since only one timer event is allowed to fire
        signal.setitimer(signal.ITIMER_REAL, t, 1000) 

def timeout(seconds):
    def timeout_handler(signum, frame):
        pass
    original_handler = signal.signal(signal.SIGALRM, timeout_handler)
    try:
        signal.alarm(seconds)
        yield
    finally:
        signal.alarm(0)
        signal.signal(signal.SIGALRM, original_handler) 

def tearDown(self):
        if task_id() is not None:
            # We're in a child process, and probably got to this point
            # via an uncaught exception.  If we return now, both
            # processes will continue with the rest of the test suite.
            # Exit now so the parent process will restart the child
            # (since we don't have a clean way to signal failure to
            # the parent that won't restart)
            logging.error("aborting child process from tearDown")
            logging.shutdown()
            os._exit(1)
        # In the surviving process, clear the alarm we set earlier
        signal.alarm(0)
        super(ProcessTest, self).tearDown() 

def test_import(self):
        TIMEOUT = 5

        # Test for a deadlock when importing a module that runs the
        # ThreadedResolver at import-time. See resolve_test.py for
        # full explanation.
        command = [sys.executable, "-c", "import tornado.test.resolve_test_helper"]

        start = time.time()
        popen = Popen(command, preexec_fn=lambda: signal.alarm(TIMEOUT))
        while time.time() - start < TIMEOUT:
            return_code = popen.poll()
            if return_code is not None:
                self.assertEqual(0, return_code)
                return  # Success.
            time.sleep(0.05)

        self.fail("import timed out")


# We do not test errors with CaresResolver:
# Some DNS-hijacking ISPs (e.g. Time Warner) return non-empty results
# with an NXDOMAIN status code.  Most resolvers treat this as an error;
# C-ares returns the results, making the "bad_host" tests unreliable.
# C-ares will try to resolve even malformed names, such as the
# name with spaces used in this test. 

def test_multiprocessing(app):
    """Tests that the number of children we produce is correct"""
    # Selects a number at random so we can spot check
    num_workers = random.choice(range(2, multiprocessing.cpu_count() * 2 + 1))
    process_list = set()

    def stop_on_alarm(*args):
        for process in multiprocessing.active_children():
            process_list.add(process.pid)
            process.terminate()

    signal.signal(signal.SIGALRM, stop_on_alarm)
    signal.alarm(3)
    app.run(HOST, PORT, workers=num_workers)

    assert len(process_list) == num_workers 

def testInterruptedTimeout(self):
        # XXX I don't know how to do this test on MSWindows or any other
        # plaform that doesn't support signal.alarm() or os.kill(), though
        # the bug should have existed on all platforms.
        self.serv.settimeout(5.0)   # must be longer than alarm
        class Alarm(Exception):
            pass
        def alarm_handler(signal, frame):
            raise Alarm
        old_alarm = signal.signal(signal.SIGALRM, alarm_handler)
        try:
            signal.alarm(2)    # POSIX allows alarm to be up to 1 second early
            try:
                foo = self.serv.accept()
            except socket.timeout:
                self.fail("caught timeout instead of Alarm")
            except Alarm:
                pass
            except:
                self.fail("caught other exception instead of Alarm:"
                          " %s(%s):\n%s" %
                          (sys.exc_info()[:2] + (traceback.format_exc(),)))
            else:
                self.fail("nothing caught")
            finally:
                signal.alarm(0)         # shut off alarm
        except Alarm:
            self.fail("got Alarm in wrong place")
        finally:
            # no alarm can be pending.  Safe to restore old handler.
            signal.signal(signal.SIGALRM, old_alarm)