python - 如何使用 Python Threading 在线程之间传递参数？

Question

1.
总结问题
我正在使用 Python 2 和运行 Raspbian Buster 的 Raspberry Pi 4。试图限制我的程序从使用套接字通过 UDP 连接发送其数据的 Android 设备读取传感器数据的速度。 IE:我将其构建为一个小型激光绊线应用程序，并且开始时，我想在每次传感器值降至某个数字以下时增加一个计数累加器，表明激光绊倒。但是，数据读取速度如此之快，以至于每次传感器水平下降时，计数都会增加很多次。我怎样才能每 X 秒读取一次 UDP 数据？
2.
描述你尝试过的

我试过 time.sleep() 但从我读过的内容来看，这是一个阻塞函数，经过测试，它确实阻止了我的程序能够通过 UDP 套接字更新传感器数据

我尝试过线程，但我无法弄清楚如何将传感器数据从一个线程传递到另一个线程。

我研究了 join() 但遇到的技术文档对初学者不太友好。

这里的一些帖子建议设置客户端/服务器接口(interface)，但我也不知道该怎么做。

3.
适当时，显示一些代码
这是我目前在线程解决方案方面的进展。我正在使用名为 SensorUDP 的 Android 应用程序，并且在环境光传感器打开并激活发送数据的情况下，该程序将读取 UDP 数据并打印它。即使没有 UDP 数据，它仍然会运行计数线程。

import socket
from struct import *
import time
import threading

#We have 0-92 over a 1024 byte buffer representing distinct
#sensors being sent over UDP from my android smartphone
#this test program im only pulling byte 56 for Ambient Light sensing
#a laser shining into my phones sensor has 30,000-50,000 lums so anything
#less then that range must mean the laser was tripped


#UDP = SOCK_DGRAM, AF_INET = Internet
UDP_IP = "192.168.1.149" #my rpi4 address
print "Receiver IP: ", UDP_IP
UDP_PORT = 5000 #arbitrary for now but needs to match my androids broadcast
print "Port: ", UDP_PORT
sock = socket.socket(socket.AF_INET, # Internet
                    socket.SOCK_DGRAM) # UDP
sock.bind((UDP_IP, UDP_PORT)) #complete the binding

running = True
count = 0
laserOn = 1000 #using a low lums to test so I dont have to use laser every time
aLight = 0
result_available = threading.Event() #.set() this when the data is recieved
threadTimer = 5

def calcAmbLight():

# Continuously read from the UDP socket
   
    while running:
       
        data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
        #the data from the app Im using to push the sensor data needs to
        #be unpacked
        aLight = "%.1f" %unpack_from ('!f', data, 56)
        print ("Ambient Light = ", aLight)

def displayCount():
    count = 0
    while running:
        time.sleep(1)
        #how to pass aLight into this thread from the other thread?
        if aLight < laserOn:
            count = count + 1

        print("Current aLight: ",aLight)
        print("Current Count: ", count)
       
if __name__ == '__main__':
              
    #create a basicthread to run calcAmbLight
    calcAmb = threading.Thread(target= calcAmbLight)
    calcAmb.start()
   
    dispCount = threading.Thread(target = displayCount)
    dispCount.start()

Answer 1

当前设置的问题是由于您没有声明 aLight作为全局 calcAmbLight() .将其声明为全局变量应该允许它工作。

def calcAmbLight():
    global aLight  # Set the global aLight, instead of a local stack variable

    while running:

        data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
        #the data from the app Im using to push the sensor data needs to
        #be unpacked
        aLight = "%.1f" %unpack_from ('!f', data, 56)
        print ("Ambient Light = ", aLight)