select.poll() is not available when using eventlet

[bobh66]

When using httpx/httpcore and eventlet together, is_socket_readable() fails with an AttributeError because poll() is not implemented in eventlet:

File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 1130, in patch
    return self.request(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 747, in request
    return self.send(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 831, in send
    response = self._send_handling_auth(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 866, in _send_handling_auth
    response = self._send_handling_redirects(
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 900, in _send_handling_redirects
    response = self._send_single_request(request, timeout)
  File "/usr/local/lib/python3.8/site-packages/httpx/_client.py", line 934, in _send_single_request
    (status_code, headers, stream, extensions) = transport.handle_request(
  File "/usr/local/lib/python3.8/site-packages/httpx/_transports/default.py", line 179, in handle_request
    status_code, headers, byte_stream, extensions = self._pool.handle_request(
  File "/usr/local/lib/python3.8/site-packages/httpcore/_sync/connection_pool.py", line 212, in handle_request
    connection = self._get_connection_from_pool(origin)
  File "/usr/local/lib/python3.8/site-packages/httpcore/_sync/connection_pool.py", line 254, in _get_connection_from_pool
    if connection.is_socket_readable():
  File "/usr/local/lib/python3.8/site-packages/httpcore/_sync/connection.py", line 172, in is_socket_readable
    return self.connection is not None and self.connection.is_socket_readable()
  File "/usr/local/lib/python3.8/site-packages/httpcore/_sync/http11.py", line 215, in is_socket_readable
    return self.socket.is_readable()
  File "/usr/local/lib/python3.8/site-packages/httpcore/_backends/sync.py", line 82, in is_readable
    return is_socket_readable(self.sock)
  File "/usr/local/lib/python3.8/site-packages/httpcore/_utils.py", line 102, in is_socket_readable
    p = select.poll()

Since this code already uses select.select() instead of select.poll() on Windows, I will push a PR to also use select.select() if poll() is unavailable.

[tomchristie]

Could you provide a minimal example that can be used to reproduce this?

[bobh66]

This seems to do it pretty reliably. Increasing the loop count causes the connection pool to get used up which triggers the problem:

eventlet.monkey_patch()

import httpx

client = httpx.Client()

for x in range(1, 10):
    client.get('http://www.google.com')

Traceback (most recent call last):
  File "/home/bobh/testhttpcore.py", line 9, in <module>
    client.get('http://www.google.com')
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 975, in get
    return self.request(
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 747, in request
    return self.send(
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 831, in send
    response = self._send_handling_auth(
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 866, in _send_handling_auth
    response = self._send_handling_redirects(
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 900, in _send_handling_redirects
    response = self._send_single_request(request, timeout)
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 934, in _send_single_request
    (status_code, headers, stream, extensions) = transport.handle_request(
  File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_transports/default.py", line 179, in handle_request
    status_code, headers, byte_stream, extensions = self._pool.handle_request(
  File "/home/bobh/git/httpcore/httpcore/_sync/http_proxy.py", line 115, in handle_request
    return self._forward_request(
  File "/home/bobh/git/httpcore/httpcore/_sync/http_proxy.py", line 145, in _forward_request
    connection = self._get_connection_from_pool(origin)
  File "/home/bobh/git/httpcore/httpcore/_sync/connection_pool.py", line 254, in _get_connection_from_pool
    if connection.is_socket_readable():
  File "/home/bobh/git/httpcore/httpcore/_sync/connection.py", line 172, in is_socket_readable
    return self.connection is not None and self.connection.is_socket_readable()
  File "/home/bobh/git/httpcore/httpcore/_sync/http11.py", line 212, in is_socket_readable
    return self.socket.is_readable()
  File "/home/bobh/git/httpcore/httpcore/_backends/sync.py", line 82, in is_readable
    return is_socket_readable(self.sock)
 File "/home/bobh/git/httpcore/httpcore/_utils.py", line 103, in is_socket_readable
    p = select.poll()
AttributeError: module 'select' has no attribute 'poll'