Python tornado.httpclient.AsyncHTTPClient.configure() Examples

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)  # type: ignore
        with closing(AsyncHTTPClient(max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)  # type: ignore

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)  # type: ignore
        with closing(AsyncHTTPClient(max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)  # type: ignore
        with closing(AsyncHTTPClient(max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14)  # type: ignore 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def __aenter__(self):
        await self.hub.initialize([])
        await self.hub.start()

        # alembic turns off all logs, reenable them for the tests
        import logging
        from tornado.log import app_log, access_log, gen_log

        logs = [app_log, access_log, gen_log, logging.getLogger("DaskGateway")]
        for log in logs:
            log.disabled = False

        # Disable curl http client for easier testing
        from tornado.httpclient import AsyncHTTPClient

        AsyncHTTPClient.configure("tornado.simple_httpclient.SimpleAsyncHTTPClient") 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def test_max_clients(self):
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)  # type: ignore
        with closing(AsyncHTTPClient(max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)  # type: ignore

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)  # type: ignore
        with closing(AsyncHTTPClient(max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)  # type: ignore
        with closing(AsyncHTTPClient(max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14)  # type: ignore 

def config(self):
        import forsun
        AsyncHTTPClient.configure(None,
                                  max_clients=config.get("ACTION_HTTP_MAX_CLIENTS", 64),
                                  defaults={"user_agent": config.get("ACTION_HTTP_USER_AGENT") or ("forsun/%s" % forsun.version)
                                  })
        self.configed = True 

def main():
    import tornado_http2.test.h2spec_test  # for option definitions
    define('httpclient', type=str, default=None)

    def configure_httpclient():
        if options.httpclient is not None:
            AsyncHTTPClient.configure(options.httpclient)
        else:
            AsyncHTTPClient.configure('tornado_http2.client.ForceHTTP2Client')
    add_parse_callback(configure_httpclient)

    logging.getLogger("tornado.access").setLevel(logging.CRITICAL)
    tornado.testing.main() 

def mock_asynchttpclient(request):
    """mock AsyncHTTPClient for recording responses"""
    AsyncHTTPClient.configure(MockAsyncHTTPClient)
    if not os.getenv('GITHUB_ACCESS_TOKEN'):
        load_mock_responses('api.github.com')
        load_mock_responses('zenodo.org') 

def init_pycurl(self):
        try:
            AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
        except ImportError as e:
            self.log.debug("Could not load pycurl: %s\npycurl is recommended if you have a large number of users.", e)
        # set max verbosity of curl_httpclient at INFO
        # because debug-logging from curl_httpclient
        # includes every full request and response
        if self.log_level < logging.INFO:
            curl_log = logging.getLogger('tornado.curl_httpclient')
            curl_log.setLevel(logging.INFO) 

def configure_ioloop():
        kwargs = {}
        if options.ioloop_time_monotonic:
            from tornado.platform.auto import monotonic_time
            if monotonic_time is None:
                raise RuntimeError("monotonic clock not found")
            kwargs['time_func'] = monotonic_time
        if options.ioloop or kwargs:
            IOLoop.configure(options.ioloop, **kwargs) 

def test_max_clients(self):
        # The max_clients argument is tricky because it was originally
        # allowed to be passed positionally; newer arguments are keyword-only.
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 10)
        with closing(AsyncHTTPClient(
                self.io_loop, 11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=11, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 11)

        # Now configure max_clients statically and try overriding it
        # with each way max_clients can be passed
        AsyncHTTPClient.configure(SimpleAsyncHTTPClient, max_clients=12)
        with closing(AsyncHTTPClient(
                self.io_loop, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 12)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=13, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 13)
        with closing(AsyncHTTPClient(
                self.io_loop, max_clients=14, force_instance=True)) as client:
            self.assertEqual(client.max_clients, 14) 

def client(io_loop, request):
    """Return mocked AsyncHTTPClient"""
    before = AsyncHTTPClient.configured_class()
    AsyncHTTPClient.configure(MockAsyncHTTPClient)
    request.addfinalizer(lambda : AsyncHTTPClient.configure(before))
    c = AsyncHTTPClient()
    assert isinstance(c, MockAsyncHTTPClient)
    return c 

def _enable_curl_httpclient(cls):
        """
        Tornado proxies are currently only supported with curl_httpclient
        http://www.tornadoweb.org/en/stable/httpclient.html#request-objects
        """
        if not cls._curl_httpclient_enabled:
            AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
            cls._curl_httpclient_enabled = True 

def configure_ioloop():
        kwargs = {}
        if options.ioloop_time_monotonic:
            from tornado.platform.auto import monotonic_time
            if monotonic_time is None:
                raise RuntimeError("monotonic clock not found")
            kwargs['time_func'] = monotonic_time
        if options.ioloop or kwargs:
            IOLoop.configure(options.ioloop, **kwargs) 

def initialize(self, max_clients=10,
                   hostname_mapping=None, max_buffer_size=104857600,
                   resolver=None, defaults=None, max_header_size=None,
                   max_body_size=None):
        """Creates a AsyncHTTPClient.

        Only a single AsyncHTTPClient instance exists per IOLoop
        in order to provide limitations on the number of pending connections.
        ``force_instance=True`` may be used to suppress this behavior.

        Note that because of this implicit reuse, unless ``force_instance``
        is used, only the first call to the constructor actually uses
        its arguments. It is recommended to use the ``configure`` method
        instead of the constructor to ensure that arguments take effect.

        ``max_clients`` is the number of concurrent requests that can be
        in progress; when this limit is reached additional requests will be
        queued. Note that time spent waiting in this queue still counts
        against the ``request_timeout``.

        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
        It can be used to make local DNS changes when modifying system-wide
        settings like ``/etc/hosts`` is not possible or desirable (e.g. in
        unittests).

        ``max_buffer_size`` (default 100MB) is the number of bytes
        that can be read into memory at once. ``max_body_size``
        (defaults to ``max_buffer_size``) is the largest response body
        that the client will accept.  Without a
        ``streaming_callback``, the smaller of these two limits
        applies; with a ``streaming_callback`` only ``max_body_size``
        does.

        .. versionchanged:: 4.2
           Added the ``max_body_size`` argument.
        """
        super(SimpleAsyncHTTPClient, self).initialize(defaults=defaults)
        self.max_clients = max_clients
        self.queue = collections.deque()
        self.active = {}
        self.waiting = {}
        self.max_buffer_size = max_buffer_size
        self.max_header_size = max_header_size
        self.max_body_size = max_body_size
        # TCPClient could create a Resolver for us, but we have to do it
        # ourselves to support hostname_mapping.
        if resolver:
            self.resolver = resolver
            self.own_resolver = False
        else:
            self.resolver = Resolver()
            self.own_resolver = True
        if hostname_mapping is not None:
            self.resolver = OverrideResolver(resolver=self.resolver,
                                             mapping=hostname_mapping)
        self.tcp_client = TCPClient(resolver=self.resolver) 

def app(request, io_loop, _binderhub_config):
    """Launch the BinderHub app

    Currently reads minikube test config from the repo.
    TODO: support input of test config files.

    Detects whether kubernetes is available, and if not disables build.
    Detects whether jupyterhub is available, and if not disables launch.

    app.url will contain the base URL of binderhub.
    """
    if REMOTE_BINDER:
        app = RemoteBinderHub()
        # wait for the remote binder to be up
        remaining = 30
        deadline = time.monotonic() + remaining
        success = False
        last_error = None
        while remaining:
            try:
                requests.get(BINDER_URL, timeout=remaining)
            except Exception as e:
                print(f"Waiting for binder: {e}")
                last_error = e
                time.sleep(1)
                remaining = deadline - time.monotonic()
            else:
                success = True
                break
        if not success:
            raise last_error
        app.url = BINDER_URL
        app._configured_bhub = BinderHub(config=_binderhub_config)
        return app

    if hasattr(request, 'param') and request.param is True:
        # load conf for auth test
        cfg = PyFileConfigLoader(minikube_testing_auth_config).load_config()
        _binderhub_config.merge(cfg)
    bhub = BinderHub.instance(config=_binderhub_config)
    bhub.initialize([])
    bhub.start(run_loop=False)
    # instantiating binderhub configures this
    # override again
    AsyncHTTPClient.configure(MockAsyncHTTPClient)

    def cleanup():
        bhub.stop()
        BinderHub.clear_instance()

    request.addfinalizer(cleanup)
    # convenience for accessing binder in tests
    bhub.url = f'http://127.0.0.1:{bhub.port}{bhub.base_url}'.rstrip('/')
    return bhub 

def initialize(self, max_clients=10,
                   hostname_mapping=None, max_buffer_size=104857600,
                   resolver=None, defaults=None, max_header_size=None,
                   max_body_size=None):
        """Creates a AsyncHTTPClient.

        Only a single AsyncHTTPClient instance exists per IOLoop
        in order to provide limitations on the number of pending connections.
        ``force_instance=True`` may be used to suppress this behavior.

        Note that because of this implicit reuse, unless ``force_instance``
        is used, only the first call to the constructor actually uses
        its arguments. It is recommended to use the ``configure`` method
        instead of the constructor to ensure that arguments take effect.

        ``max_clients`` is the number of concurrent requests that can be
        in progress; when this limit is reached additional requests will be
        queued. Note that time spent waiting in this queue still counts
        against the ``request_timeout``.

        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
        It can be used to make local DNS changes when modifying system-wide
        settings like ``/etc/hosts`` is not possible or desirable (e.g. in
        unittests).

        ``max_buffer_size`` (default 100MB) is the number of bytes
        that can be read into memory at once. ``max_body_size``
        (defaults to ``max_buffer_size``) is the largest response body
        that the client will accept.  Without a
        ``streaming_callback``, the smaller of these two limits
        applies; with a ``streaming_callback`` only ``max_body_size``
        does.

        .. versionchanged:: 4.2
           Added the ``max_body_size`` argument.
        """
        super(SimpleAsyncHTTPClient, self).initialize(defaults=defaults)
        self.max_clients = max_clients
        self.queue = collections.deque()
        self.active = {}
        self.waiting = {}
        self.max_buffer_size = max_buffer_size
        self.max_header_size = max_header_size
        self.max_body_size = max_body_size
        # TCPClient could create a Resolver for us, but we have to do it
        # ourselves to support hostname_mapping.
        if resolver:
            self.resolver = resolver
            self.own_resolver = False
        else:
            self.resolver = Resolver()
            self.own_resolver = True
        if hostname_mapping is not None:
            self.resolver = OverrideResolver(resolver=self.resolver,
                                             mapping=hostname_mapping)
        self.tcp_client = TCPClient(resolver=self.resolver) 

def initialize(self, io_loop, max_clients=10,
                   hostname_mapping=None, max_buffer_size=104857600,
                   resolver=None, defaults=None, max_header_size=None,
                   max_body_size=None):
        """Creates a AsyncHTTPClient.

        Only a single AsyncHTTPClient instance exists per IOLoop
        in order to provide limitations on the number of pending connections.
        ``force_instance=True`` may be used to suppress this behavior.

        Note that because of this implicit reuse, unless ``force_instance``
        is used, only the first call to the constructor actually uses
        its arguments. It is recommended to use the ``configure`` method
        instead of the constructor to ensure that arguments take effect.

        ``max_clients`` is the number of concurrent requests that can be
        in progress; when this limit is reached additional requests will be
        queued. Note that time spent waiting in this queue still counts
        against the ``request_timeout``.

        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
        It can be used to make local DNS changes when modifying system-wide
        settings like ``/etc/hosts`` is not possible or desirable (e.g. in
        unittests).

        ``max_buffer_size`` (default 100MB) is the number of bytes
        that can be read into memory at once. ``max_body_size``
        (defaults to ``max_buffer_size``) is the largest response body
        that the client will accept.  Without a
        ``streaming_callback``, the smaller of these two limits
        applies; with a ``streaming_callback`` only ``max_body_size``
        does.

        .. versionchanged:: 4.2
           Added the ``max_body_size`` argument.
        """
        super(SimpleAsyncHTTPClient, self).initialize(io_loop,
                                                      defaults=defaults)
        self.max_clients = max_clients
        self.queue = collections.deque()
        self.active = {}
        self.waiting = {}
        self.max_buffer_size = max_buffer_size
        self.max_header_size = max_header_size
        self.max_body_size = max_body_size
        # TCPClient could create a Resolver for us, but we have to do it
        # ourselves to support hostname_mapping.
        if resolver:
            self.resolver = resolver
            self.own_resolver = False
        else:
            self.resolver = Resolver(io_loop=io_loop)
            self.own_resolver = True
        if hostname_mapping is not None:
            self.resolver = OverrideResolver(resolver=self.resolver,
                                             mapping=hostname_mapping)
        self.tcp_client = TCPClient(resolver=self.resolver, io_loop=io_loop) 

def initialize(self, io_loop, max_clients=10,
                   hostname_mapping=None, max_buffer_size=104857600,
                   resolver=None, defaults=None, max_header_size=None,
                   max_body_size=None):
        """Creates a AsyncHTTPClient.

        Only a single AsyncHTTPClient instance exists per IOLoop
        in order to provide limitations on the number of pending connections.
        ``force_instance=True`` may be used to suppress this behavior.

        Note that because of this implicit reuse, unless ``force_instance``
        is used, only the first call to the constructor actually uses
        its arguments. It is recommended to use the ``configure`` method
        instead of the constructor to ensure that arguments take effect.

        ``max_clients`` is the number of concurrent requests that can be
        in progress; when this limit is reached additional requests will be
        queued. Note that time spent waiting in this queue still counts
        against the ``request_timeout``.

        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
        It can be used to make local DNS changes when modifying system-wide
        settings like ``/etc/hosts`` is not possible or desirable (e.g. in
        unittests).

        ``max_buffer_size`` (default 100MB) is the number of bytes
        that can be read into memory at once. ``max_body_size``
        (defaults to ``max_buffer_size``) is the largest response body
        that the client will accept.  Without a
        ``streaming_callback``, the smaller of these two limits
        applies; with a ``streaming_callback`` only ``max_body_size``
        does.

        .. versionchanged:: 4.2
           Added the ``max_body_size`` argument.
        """
        super(SimpleAsyncHTTPClient, self).initialize(io_loop,
                                                      defaults=defaults)
        self.max_clients = max_clients
        self.queue = collections.deque()
        self.active = {}
        self.waiting = {}
        self.max_buffer_size = max_buffer_size
        self.max_header_size = max_header_size
        self.max_body_size = max_body_size
        # TCPClient could create a Resolver for us, but we have to do it
        # ourselves to support hostname_mapping.
        if resolver:
            self.resolver = resolver
            self.own_resolver = False
        else:
            self.resolver = Resolver(io_loop=io_loop)
            self.own_resolver = True
        if hostname_mapping is not None:
            self.resolver = OverrideResolver(resolver=self.resolver,
                                             mapping=hostname_mapping)
        self.tcp_client = TCPClient(resolver=self.resolver, io_loop=io_loop) 

def initialize(self, io_loop, max_clients=10,
                   hostname_mapping=None, max_buffer_size=104857600,
                   resolver=None, defaults=None, max_header_size=None,
                   max_body_size=None):
        """Creates a AsyncHTTPClient.

        Only a single AsyncHTTPClient instance exists per IOLoop
        in order to provide limitations on the number of pending connections.
        ``force_instance=True`` may be used to suppress this behavior.

        Note that because of this implicit reuse, unless ``force_instance``
        is used, only the first call to the constructor actually uses
        its arguments. It is recommended to use the ``configure`` method
        instead of the constructor to ensure that arguments take effect.

        ``max_clients`` is the number of concurrent requests that can be
        in progress; when this limit is reached additional requests will be
        queued. Note that time spent waiting in this queue still counts
        against the ``request_timeout``.

        ``hostname_mapping`` is a dictionary mapping hostnames to IP addresses.
        It can be used to make local DNS changes when modifying system-wide
        settings like ``/etc/hosts`` is not possible or desirable (e.g. in
        unittests).

        ``max_buffer_size`` (default 100MB) is the number of bytes
        that can be read into memory at once. ``max_body_size``
        (defaults to ``max_buffer_size``) is the largest response body
        that the client will accept.  Without a
        ``streaming_callback``, the smaller of these two limits
        applies; with a ``streaming_callback`` only ``max_body_size``
        does.

        .. versionchanged:: 4.2
           Added the ``max_body_size`` argument.
        """
        super(SimpleAsyncHTTPClient, self).initialize(io_loop,
                                                      defaults=defaults)
        self.max_clients = max_clients
        self.queue = collections.deque()
        self.active = {}
        self.waiting = {}
        self.max_buffer_size = max_buffer_size
        self.max_header_size = max_header_size
        self.max_body_size = max_body_size
        # TCPClient could create a Resolver for us, but we have to do it
        # ourselves to support hostname_mapping.
        if resolver:
            self.resolver = resolver
            self.own_resolver = False
        else:
            self.resolver = Resolver(io_loop=io_loop)
            self.own_resolver = True
        if hostname_mapping is not None:
            self.resolver = OverrideResolver(resolver=self.resolver,
                                             mapping=hostname_mapping)
        self.tcp_client = TCPClient(resolver=self.resolver, io_loop=io_loop)