Revert "explicitly start ASGI run with empty context (#2742)"

This reverts commit d94bf28743.

tests/test_server.py

@@ -2,8 +2,6 @@ from __future__ import annotations
 
 import asyncio
 import contextlib
-import contextvars
-import json
 import logging
 import signal
 import sys
@@ -13,14 +11,12 @@ from contextlib import AbstractContextManager
 import httpx
 import pytest
 
-from tests.protocols.test_http import SIMPLE_GET_REQUEST
 from tests.utils import run_server
-from uvicorn import Server
-from uvicorn._types import ASGIApplication, ASGIReceiveCallable, ASGISendCallable, Scope
+from uvicorn._types import ASGIReceiveCallable, ASGISendCallable, Scope
 from uvicorn.config import Config
-from uvicorn.protocols.http.flow_control import HIGH_WATER_LIMIT
 from uvicorn.protocols.http.h11_impl import H11Protocol
 from uvicorn.protocols.http.httptools_impl import HttpToolsProtocol
+from uvicorn.server import Server
 
 pytestmark = pytest.mark.anyio
 
@@ -98,81 +94,3 @@ async def test_request_than_limit_max_requests_warn_log(
             responses = await asyncio.gather(*tasks)
             assert len(responses) == 2
     assert "Maximum request limit of 1 exceeded. Terminating process." in caplog.text
-
-
-@contextlib.asynccontextmanager
-async def server(*, app: ASGIApplication, port: int, http_protocol_cls: type[H11Protocol | HttpToolsProtocol]):
-    config = Config(app=app, port=port, loop="asyncio", http=http_protocol_cls)
-    server = Server(config=config)
-    task = asyncio.create_task(server.serve())
-
-    while not server.started:
-        await asyncio.sleep(0.01)
-
-    reader, writer = await asyncio.open_connection("127.0.0.1", port)
-
-    async def extract_json_body(request: bytes):
-        writer.write(request)
-        await writer.drain()
-
-        status, *headers = (await reader.readuntil(b"\r\n\r\n")).split(b"\r\n")[:-2]
-        assert status == b"HTTP/1.1 200 OK"
-
-        content_length = next(int(h.split(b":", 1)[1]) for h in headers if h.lower().startswith(b"content-length:"))
-        return json.loads(await reader.readexactly(content_length))
-
-    try:
-        yield extract_json_body
-    finally:
-        writer.close()
-        await writer.wait_closed()
-        server.should_exit = True
-        await task
-
-
-async def test_no_contextvars_pollution_asyncio(
-    http_protocol_cls: type[H11Protocol | HttpToolsProtocol], unused_tcp_port: int
-):
-    """Non-regression test for https://github.com/encode/uvicorn/issues/2167."""
-    default_contextvars = {c.name for c in contextvars.copy_context().keys()}
-    ctx: contextvars.ContextVar[str] = contextvars.ContextVar("ctx")
-
-    async def app(scope: Scope, receive: ASGIReceiveCallable, send: ASGISendCallable):
-        assert scope["type"] == "http"
-
-        # initial context should be empty
-        initial_context = {
-            n: v for c, v in contextvars.copy_context().items() if (n := c.name) not in default_contextvars
-        }
-        # set any contextvar before the body is read
-        ctx.set(scope["path"])
-
-        while True:
-            message = await receive()
-            assert message["type"] == "http.request"
-            if not message["more_body"]:
-                break
-
-        # return the initial context for empty assertion
-        body = json.dumps(initial_context).encode("utf-8")
-        headers = [(b"content-type", b"application/json"), (b"content-length", str(len(body)).encode("utf-8"))]
-        await send({"type": "http.response.start", "status": 200, "headers": headers})
-        await send({"type": "http.response.body", "body": body})
-
-    # body has to be larger than HIGH_WATER_LIMIT to trigger a reading pause on the main thread
-    # and a resumption inside the ASGI task
-    large_body = b"a" * (HIGH_WATER_LIMIT + 1)
-    large_request = b"\r\n".join(
-        [
-            b"POST /large-body HTTP/1.1",
-            b"Host: example.org",
-            b"Content-Type: application/octet-stream",
-            f"Content-Length: {len(large_body)}".encode(),
-            b"",
-            large_body,
-        ]
-    )
-
-    async with server(app=app, http_protocol_cls=http_protocol_cls, port=unused_tcp_port) as extract_json_body:
-        assert await extract_json_body(large_request) == {}
-        assert await extract_json_body(SIMPLE_GET_REQUEST) == {}

uvicorn/protocols/http/h11_impl.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import asyncio
-import contextvars
 import http
 import logging
 from collections.abc import Callable
@@ -249,12 +248,7 @@ class H11Protocol(asyncio.Protocol):
                     message_event=asyncio.Event(),
                     on_response=self.on_response_complete,
                 )
-                # For the asyncio loop, we need to explicitly start with an empty context
-                # as it can be polluted from previous ASGI runs.
-                # See https://github.com/python/cpython/issues/140947 for details.
-                task = contextvars.Context().run(self.loop.create_task, self.cycle.run_asgi(app))
-                # TODO: Replace the line above with the line below for Python >= 3.11
-                # task = self.loop.create_task(self.cycle.run_asgi(app), context=contextvars.Context())
+                task = self.loop.create_task(self.cycle.run_asgi(app))
                 task.add_done_callback(self.tasks.discard)
                 self.tasks.add(task)
 

uvicorn/protocols/http/httptools_impl.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import asyncio
-import contextvars
 import http
 import logging
 import re
@@ -289,12 +288,7 @@ class HttpToolsProtocol(asyncio.Protocol):
         )
         if existing_cycle is None or existing_cycle.response_complete:
             # Standard case - start processing the request.
-            # For the asyncio loop, we need to explicitly start with an empty context
-            # as it can be polluted from previous ASGI runs.
-            # See https://github.com/python/cpython/issues/140947 for details.
-            task = contextvars.Context().run(self.loop.create_task, self.cycle.run_asgi(app))
-            # TODO: Replace the line above with the line below for Python >= 3.11
-            # task = self.loop.create_task(self.cycle.run_asgi(app), context=contextvars.Context())
+            task = self.loop.create_task(self.cycle.run_asgi(app))
             task.add_done_callback(self.tasks.discard)
             self.tasks.add(task)
         else: