Python signal.SIGALRM Examples

def __init__(self):
        # Setup signal fd, this allows signal to behave correctly
        if os.name == 'posix':
            self.signal_pipe_r, self.signal_pipe_w = os.pipe()
            self._set_nonblock(self.signal_pipe_r)
            self._set_nonblock(self.signal_pipe_w)
            signal.set_wakeup_fd(self.signal_pipe_w)

        self._signals_received = collections.deque()

        signal.signal(signal.SIGINT, signal.SIG_DFL)
        if os.name == 'posix':
            signal.signal(signal.SIGCHLD, signal.SIG_DFL)
            signal.signal(signal.SIGTERM, self._signal_catcher)
            signal.signal(signal.SIGALRM, self._signal_catcher)
            signal.signal(signal.SIGHUP, self._signal_catcher)
        else:
            # currently a noop on window...
            signal.signal(signal.SIGTERM, self._signal_catcher)
            # FIXME(sileht): should allow to catch signal CTRL_BREAK_EVENT,
            # but we to create the child process with CREATE_NEW_PROCESS_GROUP
            # to make this work, so current this is a noop for later fix
            signal.signal(signal.SIGBREAK, self._signal_catcher) 

def test_timeout_ctx_mgr(self, test_name, exc, assertion):
        tsignal = signal.SIGALRM
        existing_handler = signal.getsignal(tsignal)
        try:
            with QdbTimeout(1, exc) as t:
                self.assertTrue(t.pending)
                time.sleep(2)
                if exc:
                    self.fail('Timeout did not stop the sleep')
        except Exception as u:
            assertion(self, u, t)
        else:
            self.assertIs(
                exc,
                False,
                'QdbTimeout(1, False) should not raise an exception'
            )

        self.assertIs(signal.getsignal(tsignal), existing_handler) 

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 start(self):
        self.last_profile_time = timer()

        if self.use_signal:
            try:
                signal.signal(signal.SIGALRM, self._signal)
                # the following tells the system to restart interrupted system calls if they are
                # interrupted before any data has been transferred. This avoids many of the problems
                # related to signals interrupting system calls, see issue #16
                signal.siginterrupt(signal.SIGALRM, False)
            except ValueError:
                raise NotMainThreadError()

            signal.setitimer(signal.ITIMER_REAL, self.interval, 0.0)
        else:
            sys.setprofile(self._profile) 

def test_rlock_acquire_interruption(self):
        # Mimic receiving a SIGINT (KeyboardInterrupt) with SIGALRM while stuck
        # in a deadlock.
        # XXX this test can fail when the legacy (non-semaphore) implementation
        # of locks is used in thread_pthread.h, see issue #11223.
        oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt)
        try:
            rlock = thread.RLock()
            # For reentrant locks, the initial acquisition must be in another
            # thread.
            def other_thread():
                rlock.acquire()
            thread.start_new_thread(other_thread, ())
            # Wait until we can't acquire it without blocking...
            while rlock.acquire(blocking=False):
                rlock.release()
                time.sleep(0.01)
            signal.alarm(1)
            t1 = time.time()
            self.assertRaises(KeyboardInterrupt, rlock.acquire, timeout=5)
            dt = time.time() - t1
            # See rationale above in test_lock_acquire_interruption
            self.assertLess(dt, 3.0)
        finally:
            signal.signal(signal.SIGALRM, oldalrm) 

def test_select_interrupt_noraise(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        orig_alrm_handler = signal.signal(signal.SIGALRM, lambda *args: None)
        self.addCleanup(signal.signal, signal.SIGALRM, orig_alrm_handler)
        self.addCleanup(signal.alarm, 0)

        signal.alarm(1)

        s.register(rd, selectors.EVENT_READ)
        t = time()
        # select() is interrupted by a signal, but the signal handler doesn't
        # raise an exception, so select() should by retries with a recomputed
        # timeout
        self.assertFalse(s.select(1.5))
        self.assertGreaterEqual(time() - t, 1.0) 

def _reproduce_preserved_alarm_stuff(self):
        preserved = self._preserved_alarm_data
        if preserved is not None:
            assert preserved.handler is not None
            # set the preserved handler as well as timeout and repeat
            # interval (if any; note: if the timeout has already passed
            # it will be set, by `_set_nonzero_alarm()`, to `MINIMAL_TIMEOUT`)
            self._signal(signal.SIGALRM, preserved.handler)
            if preserved.timeout:
                already_elapsed = time.time() - preserved.preserved_at
                self._store_alarm(preserved.timeout - already_elapsed, preserved.repeat_interval)
            else:
                self._store_alarm(0)
            self._clear_preserved_alarm_data()
        else:
            self._store_alarm(0) 

def test_select_interrupt_exc(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        class InterruptSelect(Exception):
            pass

        def handler(*args):
            raise InterruptSelect

        orig_alrm_handler = signal.signal(signal.SIGALRM, handler)
        self.addCleanup(signal.signal, signal.SIGALRM, orig_alrm_handler)
        self.addCleanup(signal.alarm, 0)

        signal.alarm(1)

        s.register(rd, selectors.EVENT_READ)
        t = time()
        # select() is interrupted by a signal which raises an exception
        with self.assertRaises(InterruptSelect):
            s.select(30)
        # select() was interrupted before the timeout of 30 seconds
        self.assertLess(time() - t, 5.0) 

def check_reentrant_write(self, data, **fdopen_kwargs):
        def on_alarm(*args):
            # Will be called reentrantly from the same thread
            wio.write(data)
            1/0
        signal.signal(signal.SIGALRM, on_alarm)
        r, w = os.pipe()
        wio = self.io.open(w, **fdopen_kwargs)
        try:
            signal.alarm(1)
            # Either the reentrant call to wio.write() fails with RuntimeError,
            # or the signal handler raises ZeroDivisionError.
            with self.assertRaises((ZeroDivisionError, RuntimeError)) as cm:
                while 1:
                    for i in range(100):
                        wio.write(data)
                        wio.flush()
                    # Make sure the buffer doesn't fill up and block further writes
                    os.read(r, len(data) * 100)
            exc = cm.exception
            if isinstance(exc, RuntimeError):
                self.assertTrue(str(exc).startswith("reentrant call"), str(exc))
        finally:
            wio.close()
            os.close(r) 

def test_timeout_start(self, test_name, exc, assertion):
        """
        Tests running a timeout with the start method that will raise itself.
        """
        tsignal = signal.SIGALRM
        existing_handler = signal.getsignal(tsignal)
        t = QdbTimeout(1, exc)
        t.start()
        with self.assertRaises(Exception) as cm:
            self.assertTrue(t.pending)
            time.sleep(2)
            if exc:
                self.fail('Timeout did not stop the sleep')

        self.assertIs(cm.exception, exc or t)
        self.assertIs(signal.getsignal(tsignal), existing_handler) 

def stop(self):
        if self.use_signal:
            signal.setitimer(signal.ITIMER_REAL, 0.0, 0.0)

            try:
                signal.signal(signal.SIGALRM, signal.SIG_IGN)
            except ValueError:
                raise NotMainThreadError()
        else:
            sys.setprofile(None) 

def __init__(self, use_signal=True):
        if use_signal:
            try:
                signal.SIGALRM
            except AttributeError:
                raise SignalUnavailableError()

        self.interval = 0.001
        self.last_profile_time = 0
        self.stack_self_time = {}
        self.use_signal = use_signal 

def test_main():
    global signal_blackboard

    signal_blackboard = { signal.SIGUSR1 : {'tripped': 0, 'tripped_by': 0 },
                          signal.SIGUSR2 : {'tripped': 0, 'tripped_by': 0 },
                          signal.SIGALRM : {'tripped': 0, 'tripped_by': 0 } }

    oldsigs = registerSignals(handle_signals, handle_signals, handle_signals)
    try:
        run_unittest(ThreadSignals)
    finally:
        registerSignals(*oldsigs) 

def set(self, time, msg):
        """
        Set the application alarm to ``time`` seconds.  If the time is
        exceeded ``signal.SIGALRM`` is raised.

        :param time: The time in seconds to set the alarm to.
        :param msg: The message to display if the alarm is triggered.
        """

        LOG.debug('setting application alarm for %s seconds' % time)
        self.msg = msg
        signal.alarm(int(time)) 

def alarm_handler(app, signum, frame):
    if signum == signal.SIGALRM:
        app.log.error(app.alarm.msg) 

def setUp(self):
        self.oldalrm = signal.signal(signal.SIGALRM, self.alarm_interrupt) 

def test_sigtimedwait_negative_timeout(self):
        signum = signal.SIGALRM
        self.assertRaises(ValueError, signal.sigtimedwait, [signum], -1.0) 

def test_sigtimedwait_poll(self):
        # check that polling with sigtimedwait works
        self.wait_helper(signal.SIGALRM, '''
        def test(signum):
            import os
            os.kill(os.getpid(), signum)
            info = signal.sigtimedwait([signum], 0)
            if info.si_signo != signum:
                raise Exception('info.si_signo != %s' % signum)
        ''') 

def test_sigtimedwait(self):
        self.wait_helper(signal.SIGALRM, '''
        def test(signum):
            signal.alarm(1)
            info = signal.sigtimedwait([signum], 10.1000)
            if info.si_signo != signum:
                raise Exception('info.si_signo != %s' % signum)
        ''') 

def test_sigwaitinfo(self):
        self.wait_helper(signal.SIGALRM, '''
        def test(signum):
            signal.alarm(1)
            info = signal.sigwaitinfo([signum])
            if info.si_signo != signum:
                raise Exception("info.si_signo != %s" % signum)
        ''') 

def test_sigwait(self):
        self.wait_helper(signal.SIGALRM, '''
        def test(signum):
            signal.alarm(1)
            received = signal.sigwait([signum])
            assert isinstance(received, signal.Signals), received
            if received != signum:
                raise Exception('received %s, not %s' % (received, signum))
        ''') 

def setUp(self):
        # isatty() and close() can hang on some platforms.  Set an alarm
        # before running the test to make sure we don't hang forever.
        old_alarm = signal.signal(signal.SIGALRM, self.handle_sig)
        self.addCleanup(signal.signal, signal.SIGALRM, old_alarm)
        self.addCleanup(signal.alarm, 0)
        signal.alarm(10) 

def check_wakeup(self, test_body, *signals, ordered=True):
        # use a subprocess to have only one thread
        code = """if 1:
        import fcntl
        import os
        import signal
        import struct

        signals = {!r}

        def handler(signum, frame):
            pass

        def check_signum(signals):
            data = os.read(read, len(signals)+1)
            raised = struct.unpack('%uB' % len(data), data)
            if not {!r}:
                raised = set(raised)
                signals = set(signals)
            if raised != signals:
                raise Exception("%r != %r" % (raised, signals))

        {}

        signal.signal(signal.SIGALRM, handler)
        read, write = os.pipe()
        for fd in (read, write):
            flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
            flags = flags | os.O_NONBLOCK
            fcntl.fcntl(fd, fcntl.F_SETFL, flags)
        signal.set_wakeup_fd(write)

        test()
        check_signum(signals)

        os.close(read)
        os.close(write)
        """.format(signals, ordered, test_body)

        assert_python_ok('-c', code) 

def setUp(self):
        self.hndl_called = False
        self.hndl_count = 0
        self.itimer = None
        self.old_alarm = signal.signal(signal.SIGALRM, self.sig_alrm) 

def test_signum(self):
        self.check_wakeup("""def test():
            import _testcapi
            signal.signal(signal.SIGUSR1, handler)
            _testcapi.raise_signal(signal.SIGUSR1)
            _testcapi.raise_signal(signal.SIGALRM)
        """, signal.SIGUSR1, signal.SIGALRM) 

def test_wakeup_fd_during(self):
        self.check_wakeup("""def test():
            import select
            import time

            TIMEOUT_FULL = 10
            TIMEOUT_HALF = 5

            class InterruptSelect(Exception):
                pass

            def handler(signum, frame):
                raise InterruptSelect
            signal.signal(signal.SIGALRM, handler)

            signal.alarm(1)
            before_time = time.monotonic()
            # We attempt to get a signal during the select call
            try:
                select.select([read], [], [], TIMEOUT_FULL)
            except InterruptSelect:
                pass
            else:
                raise Exception("select() was not interrupted")
            after_time = time.monotonic()
            dt = after_time - before_time
            if dt >= TIMEOUT_HALF:
                raise Exception("%s >= %s" % (dt, TIMEOUT_HALF))
        """, signal.SIGALRM) 

def test_wakeup_fd_early(self):
        self.check_wakeup("""def test():
            import select
            import time

            TIMEOUT_FULL = 10
            TIMEOUT_HALF = 5

            class InterruptSelect(Exception):
                pass

            def handler(signum, frame):
                raise InterruptSelect
            signal.signal(signal.SIGALRM, handler)

            signal.alarm(1)

            # We attempt to get a signal during the sleep,
            # before select is called
            try:
                select.select([], [], [], TIMEOUT_FULL)
            except InterruptSelect:
                pass
            else:
                raise Exception("select() was not interrupted")

            before_time = time.monotonic()
            select.select([read], [], [], TIMEOUT_FULL)
            after_time = time.monotonic()
            dt = after_time - before_time
            if dt >= TIMEOUT_HALF:
                raise Exception("%s >= %s" % (dt, TIMEOUT_HALF))
        """, signal.SIGALRM) 

def check_wakeup(self, test_body, *signals, ordered=True):
        # use a subprocess to have only one thread
        code = """if 1:
        import _testcapi
        import os
        import signal
        import struct

        signals = {!r}

        def handler(signum, frame):
            pass

        def check_signum(signals):
            data = os.read(read, len(signals)+1)
            raised = struct.unpack('%uB' % len(data), data)
            if not {!r}:
                raised = set(raised)
                signals = set(signals)
            if raised != signals:
                raise Exception("%r != %r" % (raised, signals))

        {}

        signal.signal(signal.SIGALRM, handler)
        read, write = os.pipe()
        os.set_blocking(write, False)
        signal.set_wakeup_fd(write)

        test()
        check_signum(signals)

        os.close(read)
        os.close(write)
        """.format(tuple(map(int, signals)), ordered, test_body)

        assert_python_ok('-c', code) 

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) 

def tearDown(self):
        signal.signal(signal.SIGALRM, self.oldalrm)