我应该在持有某个条件的锁时通知还是在释放它之后通知？

Question

Python threading documentation 列出了以下生产者示例：

from threading import Condition
cv = Condition()

# Produce one item
with cv:
    make_an_item_available()
    cv.notify()

我不得不复习线程并查看了 the C++ documentation, which states:

The notifying thread does not need to hold the lock on the same mutex as the one held by the waiting thread(s); in fact doing so is a pessimization, since the notified thread would immediately block again, waiting for the notifying thread to release the lock.

建议这样做：

# Produce one item
with cv:
    make_an_item_available()
cv.notify()

Answer 1

不要阅读 C++ 文档来理解 Python API。每 the actual Python docs:

If the calling thread has not acquired the lock when this method is called, a RuntimeError is raised.

Python 明确要求在 notifying 时保持锁定。

我应该在持有某个条件的锁时通知还是在释放它之后通知？

Should I notify while holding the lock on a condition or after releasing it?

python

multithreading

python-multithreading