Q：eventCheck函数在发布data_lock后会做什么？

当线程A解锁并立即重新锁定一个互斥锁，而另一个线程B正在等待它时，很可能A每次都是赢家，而B永远不会有机会。这并不“公平”，但在大多数操作系统中，互斥锁通常是这样实现的。
我不确定这是不是你的程序中发生的事情（顺便说一下，它被称为“饥饿”），但是如果你想让readData函数有机会绕着它的循环一圈，时不时地收集一些数据，那么你可以尝试让另一个线程时不时地释放互斥量一段时间。
也许只需要将sleep(1)调用增加四个空格就可以了？按照编写的方式，sleep(1)是不可访问的代码。

检查缩进，sleep(1)应该在while循环内：

import threading
from random import random
from time import sleep

dataRef = {}
data_lock = threading.Lock()

def simulate_external_data_source():
    return {"some_data": random()}

def readData():
    global dataRef
    dataRefNew = {}
    while True:
        dataRefsValues = simulate_external_data_source()
        with data_lock:
            dataRef = dataRefsValues
        sleep(0.5)

def eventCheck():
    global dataRef
    dataRefPrevious = {}
    dataRefActive = {}

    while True:
        with data_lock:
            if dataRefPrevious:
                dataRefActive = dataRef
                print(
                    "dataRefPrevious", dataRefPrevious, "dataRefActive", dataRefActive
                )
                dataRefPrevious = dataRefActive
            else:
                dataRefPrevious = dataRef
        sleep(1)

if __name__ == "__main__":
    thread1 = threading.Thread(target=readData)
    thread2 = threading.Thread(target=eventCheck)

    thread1.start()
    thread2.start()

    thread1.join()
    thread2.join()

字符串
印刷品：

dataRefPrevious {'some_data': 0.5985874620376193} dataRefActive {'some_data': 0.7163935517084643}
dataRefPrevious {'some_data': 0.7163935517084643} dataRefActive {'some_data': 0.22781975365213092}
dataRefPrevious {'some_data': 0.22781975365213092} dataRefActive {'some_data': 0.6816334934944924}
dataRefPrevious {'some_data': 0.6816334934944924} dataRefActive {'some_data': 0.4299086235625371}
dataRefPrevious {'some_data': 0.4299086235625371} dataRefActive {'some_data': 0.568689886521501}
dataRefPrevious {'some_data': 0.568689886521501} dataRefActive {'some_data': 0.8662567855976215}

...

型

我可能发现了一个问题，但没有明确的解释为什么...
我测试了一个函数：

def eventCheck():
   global dataRef
   dataRefPrevious = {}
   dataRefActive = {}
   i = 0
   while True:
        i +=1  
        print("\n Iteration: ", i)
        with data_lock:
            dataRefActive = dataRef
            print('dataRefActive  : ', dataRefActive)
            print('dataRefPrevious: ', dataRefPrevious)

        if dataRefPrevious:
            print('dataRefPrevious in if statment: ', dataRefPrevious)
            dataRefPrevious = dataRefActive
        else:
            dataRefPrevious = dataRefActive
        sleep(1)

字符串
我得到的是：

Iteration:  1
dataRefActive  :  {'flaps': 0.0}
dataRefPrevious:  {}

 Iteration:  2
dataRefActive  :  {'flaps': 0.0}
dataRefPrevious:  {'flaps': 0.0}
dataRefPrevious in if statment:  {'flaps': 0.0}

 Iteration:  3
dataRefActive  :  {'flaps': 1.2505772113800049}
dataRefPrevious:  {'flaps': 1.2505772113800049}
dataRefPrevious in if statment:  {'flaps': 1.2505772113800049}

 Iteration:  4
dataRefActive  :  {'flaps': 4.265423774719238}
dataRefPrevious:  {'flaps': 4.265423774719238}
dataRefPrevious in if statment:  {'flaps': 4.265423774719238}

 Iteration:  5
dataRefActive  :  {'flaps': 7.3065643310546875}
dataRefPrevious:  {'flaps': 7.3065643310546875}
dataRefPrevious in if statment:  {'flaps': 7.3065643310546875}

型

然而，当我在代码中替换以下行时：

dataRefPrevious = dataRefActive

型
收件人：

dataRefPrevious.update(dataRefActive)

型
我得到正确的价值观如下（以前不同，比活跃）

Iteration:  1
dataRefActive  :  {'flaps': 0.0}
dataRefPrevious:  {}

 Iteration:  2
dataRefActive  :  {'flaps': 0.0}
dataRefPrevious:  {'flaps': 0.0}
dataRefPrevious in if statment:  {'flaps': 0.0}

 Iteration:  3
dataRefActive  :  {'flaps': 0.20687073469161987}
dataRefPrevious:  {'flaps': 0.0}
dataRefPrevious in if statment:  {'flaps': 0.0}

 Iteration:  4
dataRefActive  :  {'flaps': 3.2361574172973633}
dataRefPrevious:  {'flaps': 0.20687073469161987}
dataRefPrevious in if statment:  {'flaps': 0.20687073469161987}

 Iteration:  5
dataRefActive  :  {'flaps': 6.276290416717529}
dataRefPrevious:  {'flaps': 3.2361574172973633}
dataRefPrevious in if statment:  {'flaps': 3.2361574172973633}

 Iteration:  6
dataRefActive  :  {'flaps': 9.321335792541504}
dataRefPrevious:  {'flaps': 6.276290416717529}
dataRefPrevious in if statment:  {'flaps': 6.276290416717529}

型

我认为=将dict dataRefPrevious的ref设置为dataRefActive dict，而.update()更改了变量本身。