python - 使用 pytest 进行测试时，如何使用 worker >= 2 干净地终止 Uvicorn + FastAPI 应用程序

Question

我有一个用 Uvicorn + FastAPI 编写的应用程序。
我正在使用 PyTest 测试响应时间。
引用How to start a Uvicorn + FastAPI in background when testing with PyTest ，我写了测试。
但是，当worker >= 2 时，我在完成测试后发现应用程序进程还活着。
我想在测试结束时干净地终止应用程序进程。
你有什么主意吗？
详细情况如下。
环境

Windows 10

Bash 4.4.23 ( https://cmder.net/ )

python 3.7.5

图书馆

fastapi == 0.68.0

unicorn == 0.14.0

请求 == 2.26.0

pytest == 6.2.4

示例代码

应用程序:main.py

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def hello_world():
    return "hello world"

测试:test_main.py

from multiprocessing import Process
import pytest
import requests
import time
import uvicorn

HOST = "127.0.0.1"
PORT = 8765
WORKERS = 1


def run_server(host: str, port: int, workers: int, wait: int = 15) -> Process:
    proc = Process(
        target=uvicorn.run,
        args=("main:app",),
        kwargs={
            "host": host,
            "port": port,
            "workers": workers,
        },
    )
    proc.start()
    time.sleep(wait)
    assert proc.is_alive()
    return proc


def shutdown_server(proc: Process):
    proc.terminate()
    for _ in range(5):
        if proc.is_alive():
            time.sleep(5)
        else:
            return
    else:
        raise Exception("Process still alive")


def check_response(host: str, port: int):
    assert requests.get(f"http://{host}:{port}").text == '"hello world"'


def check_response_time(host: str, port: int, tol: float = 1e-2):
    s = time.time()
    requests.get(f"http://{host}:{port}")
    e = time.time()
    assert e-s < tol


@pytest.fixture(scope="session")
def server():
    proc = run_server(HOST, PORT, WORKERS)
    try:
        yield
    finally:
        shutdown_server(proc)


def test_main(server):
    check_response(HOST, PORT)
    check_response_time(HOST, PORT)
    check_response(HOST, PORT)
    check_response_time(HOST, PORT)

执行结果

$ curl http://localhost:8765
curl: (7) Failed to connect to localhost port 8765: Connection refused
$ pytest test_main.py
=============== test session starts =============== platform win32 -- Python 3.7.5, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: .\
collected 1 item

test_main.py .                                                                                                                                                                                                                         [100%]

=============== 1 passed in 20.23s ===============
$ curl http://localhost:8765
curl: (7) Failed to connect to localhost port 8765: Connection refused
$ sed -i -e "s/WORKERS = 1/WORKERS = 3/g" test_main.py
$ curl http://localhost:8765
curl: (7) Failed to connect to localhost port 8765: Connection refused
$ pytest test_main.py
=============== test session starts =============== platform win32 -- Python 3.7.5, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: .\
collected 1 item

test_main.py .                                                                                                                                                                                                                         [100%]

=============== 1 passed in 20.21s ===============
$ curl http://localhost:8765
"hello world"

$ # Why is localhost:8765 still alive?

Answer 1

我自己找到了解决方案。
谢谢 > https://stackoverflow.com/a/27034438/16567832
解决方案
通过 pip install psutil 安装 psutil 后, 更新 test_main.py

from multiprocessing import Process
import psutil
import pytest
import requests
import time
import uvicorn

HOST = "127.0.0.1"
PORT = 8765
WORKERS = 3


def run_server(host: str, port: int, workers: int, wait: int = 15) -> Process:
    proc = Process(
        target=uvicorn.run,
        args=("main:app",),
        kwargs={
            "host": host,
            "port": port,
            "workers": workers,
        },
    )
    proc.start()
    time.sleep(wait)
    assert proc.is_alive()
    return proc


def shutdown_server(proc: Process):

    ##### SOLUTION #####
    pid = proc.pid
    parent = psutil.Process(pid)
    for child in parent.children(recursive=True):
        child.kill()
    ##### SOLUTION END ####

    proc.terminate()
    for _ in range(5):
        if proc.is_alive():
            time.sleep(5)
        else:
            return
    else:
        raise Exception("Process still alive")


def check_response(host: str, port: int):
    assert requests.get(f"http://{host}:{port}").text == '"hello world"'


def check_response_time(host: str, port: int, tol: float = 1e-2):
    s = time.time()
    requests.get(f"http://{host}:{port}")
    e = time.time()
    assert e-s < tol


@pytest.fixture(scope="session")
def server():
    proc = run_server(HOST, PORT, WORKERS)
    try:
        yield
    finally:
        shutdown_server(proc)


def test_main(server):
    check_response(HOST, PORT)
    check_response_time(HOST, PORT)
    check_response(HOST, PORT)
    check_response_time(HOST, PORT)

执行结果

$ curl http://localhost:8765
curl: (7) Failed to connect to localhost port 8765: Connection refused
$ pytest test_main.py
================== test session starts ================== platform win32 -- Python 3.7.5, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: .\
collected 1 item

test_main.py .                                                                                                                                                                                                                         [100%]

================== 1 passed in 20.24s ==================
$ curl http://localhost:8765
curl: (7) Failed to connect to localhost port 8765: Connection refused