'NameError：即使已导入全局名称'subprocess'，也未定义'

Question

I keep on getting the error NameError: global name 'subprocess' is not defined when running this script.

I've tried importing subprocess inside the __init__ function of the ProgramBody class, but that did not do anything to change the error. I've also tried to use from subprocess import check_output but that would just give me the same NameError but with check_output instead of subprocess .

I put the import inside of the function get_speed and set_speed functions at one point out of desperation, and it worked; but a solution such as that is very unfeasible as those functions will be called ~4 times a second.

Code

import subprocess
import time
import threading

class ProgramBody():
    def __init__(self):
        self.current_speed = 0
        self.current_temp = 0
        self.update = True
        self.change = True
        self.update_wait = 0.25

    def get_speed (self):
        return subprocess.check_output (["nvidia-settings", "-tq", "[fan:0]/GPUCurrentFanSpeed"])
    def set_speed (self, speed):
        subprocess.call (["nvidia-settings", "-a", "[gpu:0]/GPUFanControlState=1", "-a", "[fan:0]/GPUTargetFanSpeed=" + str(speed)])
    def get_temp (self):
        return subprocess.check_output (["nvidia-settings", "-tq", "[gpu:0]/GPUCoreTemp"])

    def const_update(self):
        while self.update:
            self.current_speed = self.get_speed ()
            self.current_temp = self.get_temp ()
            time.sleep (self.update_wait)

class ThreadingExample(object):
    def __init__(self, interval=1):
        thread = threading.Thread(target=self.run, args=())
        thread.daemon = True
        thread.start()

    def run(self):
        body.const_update()


body = ProgramBody()
thread = ThreadingExample()

Stacktrace

(Pdb) Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 763, in run
    self.__target(*self.__args, **self.__kwargs)
  File "FanSpeed.py", line 42, in run
    body.const_update()
  File "FanSpeed.py", line 32, in const_update
    self.current_temp = self.get_temp ()
  File "FanSpeed.py", line 27, in get_temp
    return subprocess.check_output (["nvidia-settings", "-tq", "[gpu:0]/GPUCoreTemp"])
NameError: global name 'subprocess' is not defined

Python 2.7.10

Answer 1

You dont have a method to join the thread after it starts or finishes.

I do however get an exception

WindowsError: [Error 2] The system cannot find the file specified

This is because we need to tell subprocess where to find the executable nvidia-settings.

import subprocess
import time
import threading

class ProgramBody():
    def __init__(self):
    self.current_speed = 0
    self.current_temp = 0
    self.update = True
    self.change = True
    self.update_wait = 0.25

    def get_speed (self):
        return subprocess.check_output (["nvidia-settings", "-tq", "[fan:0]/GPUCurrentFanSpeed"])
    def set_speed (self, speed):
        subprocess.call (["nvidia-settings", "-a", "[gpu:0]/GPUFanControlState=1", "-a", "[fan:0]/GPUTargetFanSpeed=" + str(speed)])
    def get_temp (self):
        return subprocess.check_output (["nvidia-settings", "-tq", "[gpu:0]/GPUCoreTemp"])

    def const_update(self):
        while self.update:
            self.current_speed = self.get_speed ()
            self.current_temp = self.get_temp ()
            time.sleep (self.update_wait)

class ThreadingExample():
    def __init__(self, interval=1):
        self.thread = threading.Thread(target=self.run, args=())
        self.thread.daemon = True
        self.thread.start()

    def run(self):
        body.const_update()

    def stop(self):
        self.thread.join()


body = ProgramBody()
thread = ThreadingExample()
thread.stop()

I have modified the processes to be ['ls', '-lah'] and added before time.sleep the following and it works appropriately.

print self.current_speed
import sys
sys.stdout.flush()