Why is my Python script causing 100% processor usage? While loop to monitor GPIO button

Question

import json
from gpiozero import Button
from time import sleep
from mpd import MPDClient

button = Button(23)
while True:
    if button.is_pressed:
        client = MPDClient()               # create client object
        client.timeout = 10                # network timeout in seconds (floats allowed), default: None
        client.idletimeout = None          # timeout for fetching the result of the idle command is handled seperately, default: None
        client.connect("localhost", 6600)  # connect to localhost:6600
        client.load("Radio")
        if (client.status()['state']=="play"):
            client.pause()
        else:
            client.play()
        sleep(1.25)
        print ("State is:")
        print (client.status()['state'])
        client.close()                     # send the close command
        client.disconnect()                # disconnect from the server

I call this script in my bashrc file:

python ~/scripts/gpio/gpiompdstartstop.py &

I tried increasing the sleep time within the cycle, but it doesn't help at all...

I am considering investigating how to use a subprocess call, but I'm not sure it would help, nor how to go about it.

Thank you for any help.

Answer 1

The sleep is only executed if the button is pressed. You need a sleep between checks for the button press to let other processes run.

E.g.

while True:
    if button.is_pressed:
        # do work
    time.sleep(0.05) # check for button press 20 times a second.

Answer 2

GpioZero is far easier for beginners to use (and unlike RPi.GPIO it ACTUALLY has DOCUMENTATION and EXAMPLES)

See the Button class

I would probably use when_pressed. As your code is doing little you could use wait_for_press which will block until needed.

Incidentally calling from .bashrc is an extremely POOR practice. This is designed for configuring the shell NOT running programs.