[Errno 99] Cannot assign requested address

[coderanger]

This might be better over on the httpcore repo but I figured I would start here. We have a WSGI app running under a threaded server and very very rarely we get [Errno 99] Cannot assign requested address when it tries to make an outbound request. My understanding is this shouldn't happen, maybe some kind of listen port collision between threads? Stack trace is below.

User.DoesNotExist: User matching query does not exist.
  File "wallspice_auth/backends.py", line 249, in authenticate
    user = User._default_manager.get(
  File "django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "django/db/models/query.py", line 406, in get
    raise self.model.DoesNotExist(

OSError: [Errno 99] Cannot assign requested address
  File "httpcore/_exceptions.py", line 8, in map_exceptions
    yield
  File "httpcore/backends/sync.py", line 82, in connect_tcp
    sock = socket.create_connection(
  File "socket.py", line 808, in create_connection
    raise err
  File "socket.py", line 796, in create_connection
    sock.connect(sa)

ConnectError: [Errno 99] Cannot assign requested address
  File "httpx/_transports/default.py", line 60, in map_httpcore_exceptions
    yield
  File "httpx/_transports/default.py", line 218, in handle_request
    resp = self._pool.handle_request(req)
  File "httpcore/_sync/connection_pool.py", line 253, in handle_request
    raise exc
  File "httpcore/_sync/connection_pool.py", line 237, in handle_request
    response = connection.handle_request(request)
  File "httpcore/_sync/connection.py", line 86, in handle_request
    raise exc
  File "httpcore/_sync/connection.py", line 63, in handle_request
    stream = self._connect(request)
  File "httpcore/_sync/connection.py", line 111, in _connect
    stream = self._network_backend.connect_tcp(**kwargs)
  File "httpcore/backends/sync.py", line 82, in connect_tcp
    sock = socket.create_connection(
  File "contextlib.py", line 131, in __exit__
    self.gen.throw(type, value, traceback)
  File "httpcore/_exceptions.py", line 12, in map_exceptions
    raise to_exc(exc)

ConnectError: [Errno 99] Cannot assign requested address
  File "django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "django/utils/deprecation.py", line 93, in __call__
    response = self.process_request(request)
  File "wallspice_auth/middleware.py", line 107, in process_request
    user = auth.authenticate(request, token=md.group(1))
  File "django/contrib/auth/__init__.py", line 73, in authenticate
    user = backend.authenticate(request, **credentials)
  File "wallspice_auth/backends.py", line 254, in authenticate
    user = self._create_user(request, decoded, token, key_algorithm, key_id)
  File "wallspice_auth/backends.py", line 289, in _create_user
    email, email_verified = self._get_email(
  File "wallspice_auth/backends.py", line 382, in _get_email
    return self._get_auth0_email(decoded, token)
  File "wallspice_auth/backends.py", line 421, in _get_auth0_email
    resp = self.httpx_client.get(
  File "httpx/_client.py", line 1025, in get
    return self.request(
  File "httpx/_client.py", line 802, in request
    return self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "httpx/_client.py", line 889, in send
    response = self._send_handling_auth(
  File "httpx/_client.py", line 917, in _send_handling_auth
    response = self._send_handling_redirects(
  File "httpx/_client.py", line 954, in _send_handling_redirects
    response = self._send_single_request(request)
  File "httpx/_client.py", line 990, in _send_single_request
    response = transport.handle_request(request)
  File "httpx/_transports/default.py", line 218, in handle_request
    resp = self._pool.handle_request(req)
  File "contextlib.py", line 131, in __exit__
    self.gen.throw(type, value, traceback)
  File "httpx/_transports/default.py", line 77, in map_httpcore_exceptions
    raise mapped_exc(message) from exc