python - mock.call_count 的线程安全版本

Question

看起来 Mock.call_count不能与线程一起正常工作。例如:

import threading
import time
from mock import MagicMock


def f():
    time.sleep(0.1)

def test_1():
    mock = MagicMock(side_effect=f)
    nb_threads = 100000
    threads = []
    for _ in range(nb_threads):
        thread = threading.Thread(target=mock)
        threads.append(thread)
        thread.start()

    for thread in threads:
        thread.join()

    assert mock.call_count == nb_threads, mock.call_count

test_1()

此代码产生以下输出:

Traceback (most recent call last):
  File "test1.py", line 24, in <module>
    test_1()
  File "test1.py", line 21, in test_1
    assert mock.call_count == nb_threads, mock.call_count
AssertionError: 99994

有没有一种方法可以在代码的多线程部分中使用 call_count(或类似的)？我想避免自己重写 MagicMock...

Answer 1

我最终通过使用一个链接到副作用方法的计数器和一个锁让它工作。

import threading
import time
from mock import MagicMock

lock_side_effect = threading.Lock()

def f():
    with lock_side_effect:
        f.call_count += 1
    time.sleep(0.1)

f.call_count = 0

def test_1():
    mock = MagicMock(side_effect=f)
    nb_threads = 100000
    threads = []
    for _ in range(nb_threads):
        thread = threading.Thread(target=mock)
        threads.append(thread)
        thread.start()

    for thread in threads:
        thread.join()

    assert f.call_count == nb_threads, f.call_count

test_1()

因此，我正在计算 f 而不是 mock 的调用次数，但结果符合预期。