Python asyncio.set_event_loop_policy() Examples

def event_loop(request):
    """Overwrite `pytest_asyncio` eventloop to fix Windows issue.

    Default implementation causes `NotImplementedError` on Windows with
    Python 3.8, because they changed default eventloop in 3.8.

    NOTE: We do the same thing in the `example/settings.py` because it
    imports (and fails) before we have a chance to invoke this fixture.
    So, we could avoid adding this fixture, but I feel it is better to
    keep the proper solution here as well.

    """
    if sys.platform == "win32" and sys.version_info.minor >= 8:
        asyncio.set_event_loop_policy(
            asyncio.WindowsSelectorEventLoopPolicy()  # pylint: disable=no-member
        )
    loop = asyncio.get_event_loop_policy().new_event_loop()
    yield loop
    loop.close() 

def uvloop_worker(
    config: Config, sockets: Optional[Sockets] = None, shutdown_event: Optional[EventType] = None
) -> None:
    try:
        import uvloop
    except ImportError as error:
        raise Exception("uvloop is not installed") from error
    else:
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

    app = load_application(config.application_path)

    shutdown_trigger = None
    if shutdown_event is not None:
        shutdown_trigger = partial(check_multiprocess_shutdown_event, shutdown_event, asyncio.sleep)

    _run(
        partial(worker_serve, app, config, sockets=sockets),
        debug=config.debug,
        shutdown_trigger=shutdown_trigger,
    ) 

def test_get_event_loop_returns_running_loop(self):
        class Policy(asyncio.DefaultEventLoopPolicy):
            def get_event_loop(self):
                raise NotImplementedError

        loop = None

        old_policy = asyncio.get_event_loop_policy()
        try:
            asyncio.set_event_loop_policy(Policy())
            loop = asyncio.new_event_loop()
            self.assertIs(asyncio._get_running_loop(), None)

            async def func():
                self.assertIs(asyncio.get_event_loop(), loop)
                self.assertIs(asyncio._get_running_loop(), loop)

            loop.run_until_complete(func())
        finally:
            asyncio.set_event_loop_policy(old_policy)
            if loop is not None:
                loop.close()

        self.assertIs(asyncio._get_running_loop(), None) 

def __init__(self,instance,host="localhost",port=None,autoreload=False):
        super(WebServer, self).__init__()
        self.app=None
        self.instance=instance
        self.host=host
        self.autoreload=autoreload

        if port is not None:
            self.port = port

        while not isFree("localhost", self.port):
            self.port += 1

        self.instance._webserver=(self.host,self.port)

        try: # https://bugs.python.org/issue37373 FIX: tornado/py3.8 on windows
            if sys.platform == 'win32':
                asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
        except:
            pass 

def __init__(self, verbosity=0, max_tasks=512):
        """Constructor.

        Args:
            verbosity: set output verbosity: 0 (default) is none, 3 is debug
            max_tasks: the maximum number of tasks asyncio will queue (default 512)
        """
        self.tasks = []
        self.errors = []
        self.fqdn = []
        self.ignore_hosts = []
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
        self.loop = asyncio.get_event_loop()
        self.resolver = aiodns.DNSResolver(loop=self.loop, rotate=True)
        self.sem = asyncio.BoundedSemaphore(max_tasks)
        self.max_tasks = max_tasks
        self.verbosity = verbosity
        self.logger = ConsoleLogger(verbosity) 

def main():
    args = parse_args()
    if args.uvloop:
        import uvloop
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

    loop = asyncio.get_event_loop()
    task = loop.create_task(Benchmark(args).bench_simple())
    task.add_done_callback(lambda _, loop=loop: loop.stop())

    def signal_hndl(_task=task):
        _task.cancel()
    loop.add_signal_handler(signal.SIGTERM, signal_hndl)
    loop.add_signal_handler(signal.SIGINT, signal_hndl)

    try:
        loop.run_forever()
    finally:
        loop.close()
        if not task.cancelled():
            task.result() 

def main():
    args = parse_args()
    if args.uvloop:
        import uvloop
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

    loop = asyncio.get_event_loop()
    task = loop.create_task(Benchmark(args).bench_simple())
    task.add_done_callback(lambda _, loop=loop: loop.stop())

    def signal_hndl(_task=task):
        _task.cancel()
    loop.add_signal_handler(signal.SIGTERM, signal_hndl)
    loop.add_signal_handler(signal.SIGINT, signal_hndl)

    try:
        loop.run_forever()
    finally:
        loop.close()
        if not task.cancelled():
            task.result() 

def _init_asyncio_patch():
    """
    Select compatible event loop for Tornado 5+.
    As of Python 3.8, the default event loop on Windows is `proactor`,
    however Tornado requires the old default "selector" event loop.
    As Tornado has decided to leave this to users to set, MkDocs needs
    to set it. See https://github.com/tornadoweb/tornado/issues/2608.
    """
    if sys.platform.startswith("win") and sys.version_info >= (3, 8):
        import asyncio
        try:
            from asyncio import WindowsSelectorEventLoopPolicy
        except ImportError:
            pass  # Can't assign a policy which doesn't exist.
        else:
            if not isinstance(asyncio.get_event_loop_policy(), WindowsSelectorEventLoopPolicy):
                asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy()) 

def init(self, path_app_root, path_data):
        log.initialize()

        asyncio.set_event_loop_policy(tornado.platform.asyncio.AnyThreadEventLoopPolicy())

        cfg = tp_cfg()
        cfg.app_path = path_app_root
        cfg.static_path = os.path.join(path_app_root, 'static')
        cfg.template_path = os.path.join(path_app_root, 'view')
        cfg.res_path = os.path.join(path_app_root, 'res')

        cfg.data_path = path_data
        cfg.cfg_path = os.path.join(path_data, 'etc')
        cfg.log_path = os.path.join(path_data, 'log')

        self._cfg_file = os.path.join(cfg.cfg_path, 'web.ini')
        if not cfg.load(self._cfg_file):
            return False

        return True 

def main() -> int:
    print("Hello, World!")

    asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

    loop = asyncio.get_event_loop()
    # Each client connection will create a new protocol instance
    coro = loop.create_server(RedisProtocol, "127.0.0.1", 7878)
    server = loop.run_until_complete(coro)

    # Serve requests until Ctrl+C is pressed
    print('Serving on {}'.format(server.sockets[0].getsockname()))
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass

    # Close the server
    server.close()
    loop.run_until_complete(server.wait_closed())
    loop.close()

    return 0 

def asyncio_worker(
    config: Config, sockets: Optional[Sockets] = None, shutdown_event: Optional[EventType] = None
) -> None:
    app = load_application(config.application_path)

    shutdown_trigger = None
    if shutdown_event is not None:
        shutdown_trigger = partial(check_multiprocess_shutdown_event, shutdown_event, asyncio.sleep)

    if config.workers > 1 and platform.system() == "Windows":
        asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())  # type: ignore

    _run(
        partial(worker_serve, app, config, sockets=sockets),
        debug=config.debug,
        shutdown_trigger=shutdown_trigger,
    ) 

def test_it_logs_messages(self):
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
        loop = asyncio.get_event_loop()

        async def test():
            reader = asyncio.StreamReader(loop=loop)
            protocol = asyncio.StreamReaderProtocol(reader)

            transport, _ = await loop.connect_read_pipe(
                lambda: protocol, self.read_pipe
            )

            logger = Logger.with_default_handlers()
            await logger.info("Xablau")

            logged_content = await reader.readline()
            self.assertEqual(logged_content, b"Xablau\n")

            transport.close()
            await logger.shutdown()

        loop.run_until_complete(test()) 

def main():
    args = parse_args()
    if args.uvloop:
        import uvloop
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

    loop = asyncio.get_event_loop()
    task = loop.create_task(Benchmark(args).bench_simple())
    task.add_done_callback(lambda _, loop=loop: loop.stop())

    def signal_hndl(_task=task):
        _task.cancel()
    loop.add_signal_handler(signal.SIGTERM, signal_hndl)
    loop.add_signal_handler(signal.SIGINT, signal_hndl)

    try:
        loop.run_forever()
    finally:
        loop.close()
        if not task.cancelled():
            task.result() 

def main():
    args = parse_args()
    if args.uvloop:
        import uvloop
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

    loop = asyncio.get_event_loop()
    task = loop.create_task(Benchmark(args).bench_simple())
    task.add_done_callback(lambda _, loop=loop: loop.stop())

    def signal_hndl(_task=task):
        _task.cancel()
    loop.add_signal_handler(signal.SIGTERM, signal_hndl)
    loop.add_signal_handler(signal.SIGINT, signal_hndl)

    try:
        loop.run_forever()
    finally:
        loop.close()
        if not task.cancelled():
            task.result() 

def _init_asyncio_patch():
    """
    Select compatible event loop for Tornado 5+.

    As of Python 3.8, the default event loop on Windows is `proactor`,
    however Tornado requires the old default "selector" event loop.
    As Tornado has decided to leave this to users to set, MkDocs needs
    to set it. See https://github.com/tornadoweb/tornado/issues/2608.
    """
    if sys.platform.startswith("win") and sys.version_info >= (3, 8):
        import asyncio
        try:
            from asyncio import WindowsSelectorEventLoopPolicy
        except ImportError:
            pass  # Can't assign a policy which doesn't exist.
        else:
            if not isinstance(asyncio.get_event_loop_policy(), WindowsSelectorEventLoopPolicy):
                asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy()) 

def init_process(self):
        import uvloop

        # Close any existing event loop before setting a
        # new policy.
        asyncio.get_event_loop().close()

        # Setup uvloop policy, so that every
        # asyncio.get_event_loop() will create an instance
        # of uvloop event loop.
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

        super().init_process() 

def setup_asyncio(config: util.config.Config) -> asyncio.AbstractEventLoop:
    """Returns a new asyncio event loop with settings from the given config."""

    asyncio_config: util.config.AsyncIOConfig = config["asyncio"]

    if sys.platform == "win32":
        # Force ProactorEventLoop on Windows for subprocess support
        policy = asyncio.WindowsProactorEventLoopPolicy()
        asyncio.set_event_loop_policy(policy)
    elif not asyncio_config["disable_uvloop"]:
        # Initialize uvloop if available
        try:
            # noinspection PyUnresolvedReferences
            import uvloop

            uvloop.install()
            log.info("Using uvloop event loop")
        except ImportError:
            pass

    loop = asyncio.new_event_loop()

    if asyncio_config["debug"]:
        log.info("Enabling asyncio debug mode")
        loop.set_debug(True)

    return loop 

def init_process(self):
        import tokio

        # Close any existing event loop before setting a
        # new policy.
        asyncio.get_event_loop().close()

        # Setup tokio policy, so that every
        # asyncio.get_event_loop() will create an instance
        # of tokio event loop.
        asyncio.set_event_loop_policy(tokio.EventLoopPolicy())

        super().init_process() 

def init_process(self):
        import uvloop

        # Close any existing event loop before setting a
        # new policy.
        asyncio.get_event_loop().close()

        # Setup uvloop policy, so that every
        # asyncio.get_event_loop() will create an instance
        # of uvloop event loop.
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

        super().init_process() 

def pytest_sessionstart(session):
    """
    Called after the Session object has been created and
    before performing collection and entering the run test loop.
    """
    # The default event loop on Windows causes an exception saying Event loop
    # closed to be thrown on Python 3.8 with Windows
    # https://github.com/encode/httpx/issues/914
    if (
        sys.version_info[0] == 3
        and sys.version_info[1] >= 8
        and sys.platform.startswith("win")
    ):
        asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy()) 

def test_set_event_loop_policy(self):
        self.assertRaises(
            AssertionError, asyncio.set_event_loop_policy, object())

        old_policy = asyncio.get_event_loop_policy()

        policy = asyncio.DefaultEventLoopPolicy()
        asyncio.set_event_loop_policy(policy)
        self.assertIs(policy, asyncio.get_event_loop_policy())
        self.assertIsNot(policy, old_policy) 

def uvloop_loop():
    asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
    loop = asyncio.get_event_loop()
    yield loop
    loop.close()
    # restore the virgin state
    asyncio.set_event_loop_policy(uvloop.EventLoopPolicy()) 

def asyncio_loop():
    asyncio.set_event_loop_policy(None)
    loop = asyncio.get_event_loop()
    yield loop
    loop.close()
    # restore the virgin state
    asyncio.set_event_loop_policy(None) 

def test_set_event_loop_policy(self):
        self.assertRaises(
            AssertionError, asyncio.set_event_loop_policy, object())

        old_policy = asyncio.get_event_loop_policy()

        policy = asyncio.DefaultEventLoopPolicy()
        asyncio.set_event_loop_policy(policy)
        self.assertIs(policy, asyncio.get_event_loop_policy())
        self.assertIsNot(policy, old_policy) 

def _process_command(args: List[str], input_data: str, read_callback: Callable[[str], None]):
    work = _process_command_async(args, input_data, read_callback)

    if IO_LOOP is None:
        if _is_windows():
            asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())
        asyncio.run(work)
    else:
        asyncio.run_coroutine_threadsafe(work, IO_LOOP).result() 

def _unset_loop(self):
        policy = asyncio.get_event_loop_policy()

        if not self.use_default_loop:
            if sys.version_info >= (3, 6):
                self.loop.run_until_complete(self.loop.shutdown_asyncgens())
            self.loop.close()
            policy.reset_watcher()

        asyncio.set_event_loop_policy(policy.original_policy)
        self.loop = None 

def _init_loop(self):
        if self.use_default_loop:
            self.loop = asyncio.get_event_loop()
            loop = None
        else:
            loop = self.loop = asyncio.new_event_loop()

        policy = _Policy(asyncio.get_event_loop_policy(),
                         loop, self.forbid_get_event_loop)

        asyncio.set_event_loop_policy(policy)

        self.loop = self._patch_loop(self.loop) 

def enable_uvloop():  # pragma: no cover
    try:
        # pylint: disable=import-outside-toplevel
        import uvloop
        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
    except ImportError:
        return False
    else:
        return True 

def tearDownModule():
    asyncio.set_event_loop_policy(None) 

def loop(loop_factory, fast, loop_debug):  # type: ignore
    """Return an instance of the event loop."""
    policy = loop_factory()
    asyncio.set_event_loop_policy(policy)
    with loop_context(fast=fast) as _loop:
        if loop_debug:
            _loop.set_debug(True)  # pragma: no cover
        asyncio.set_event_loop(_loop)
        yield _loop