[英]How to terminate a thread in Python?
I know the topic has been covered a few times however I have attempted, or at least tried virtually all solutions however being a fairly new python basher I've not been able to get any of the previous solutions to work.我知道这个话题已经讨论过几次,但是我已经尝试过,或者至少尝试了几乎所有的解决方案,但是作为一个相当新的 python basher,我无法让以前的任何解决方案起作用。
The basic premise of the script is that its subscribed to a MQTT broker and waiting for commands, the single action commands work 100%, however one of the commands required a loop to run indefinitely until another command is received, thus the most appropriate solution was to run the "loop" in a separate thread while the main subscriber loop continues to "listen" for the next command.该脚本的基本前提是它订阅了一个 MQTT 代理并等待命令,单个动作命令 100% 工作,但是其中一个命令需要一个循环无限期地运行,直到收到另一个命令,因此最合适的解决方案是在一个单独的线程中运行“循环”,而主订阅者循环继续“监听”下一个命令。
Everything is working 95%, the "static" commands come through and the tasks is run fine, then when the "mtg" command comes through it actions the thread and the loop runs 100%, however this is where it falls down, when the next command is received I can confirm the "if" statement processes the command as it prints the message to the console, but the thread.stop() is not run, or it may be run but it does not terminate the thread --- I'm pulling my hair out trying to figure it out.一切都在工作 95%,“静态”命令通过并且任务运行良好,然后当“mtg”命令通过它时,线程和循环运行 100%,但是这是它失败的地方,当收到下一个命令我可以确认“if”语句在将消息打印到控制台时处理命令,但是 thread.stop() 没有运行,或者它可能运行但它不会终止线程 ---我正在拔头发试图弄清楚。
Some code:一些代码:
from sys import exit
import blinkt
import threading
import time
MQTT_SERVER = '192.168.x.x'
MQTT_PORT = 1883
MQTT_TOPIC = 'mytopic'
REDS = [0, 0, 0, 0, 0, 16, 64, 255, 64, 16, 0, 0, 0, 0, 0, 0]
start_time = time.time()
class task(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.kill = threading.Event()
self.event = threading.Event()
self._stop = threading.Event()
def run(self):
# while not self.kill.is_set():
while True:
if self.stopped():
return
self.start_run()
def stop(self):
# self.event.set()
self._stop.set()
def stopped(self):
return self._stop.isSet()
def start_run(self):
# while True: <-- no longer needed as the run method loops the process.
delta = (time.time() - start_time) * 16
offset = int(abs((delta % len(REDS)) - blinkt.NUM_PIXELS))
for i in range(blinkt.NUM_PIXELS):
blinkt.set_pixel(i, REDS[offset + i], 0, 0)
blinkt.show()
time.sleep(0.1)
def on_connect(client, userdata, flags, rc):
print('Connected with result code ' + str(rc))
client.subscribe(MQTT_TOPIC)
def on_message(client, userdata, msg):
data = msg.payload
if type(data) is bytes:
data = data.decode('utf-8')
data = data.split(',')
command = data.pop(0)
if command == 'clr' and len(data) == 0:
blinkt.clear()
blinkt.show()
t1.stop() #<--- I've tried a few ways to get the task to stop when the "clr" command is recieved
task.stop()
return
if command == 'rgb' and len(data) == 4: #<-- This code block works fine, msg arrives and LEDs are set correctly
try:
pixel = data.pop(0)
if pixel == '*':
pixel = None
else:
pixel = int(pixel)
if pixel > 7:
print('Pixel out of range: ' + str(pixel))
return
r, g, b = [int(x) & 0xff for x in data]
print(command, pixel, r, g, b)
except ValueError:
print('Malformed command: ' + str(msg.payload))
return
if pixel is None:
for x in range(blinkt.NUM_PIXELS):
blinkt.set_pixel(x, r, g, b)
else:
blinkt.set_pixel(pixel, r, g, b)
blinkt.show()
return
if command == 'mtg' and len(data) == 0:
print(command)
t1 = task()
t1.start() #<-- Here is where the Thread is called to start and seems to run ok
return
blinkt.set_clear_on_exit()
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect(MQTT_SERVER, MQTT_PORT, 60)
client.loop_forever()
Your t1
variable is a local, so it gets lost when you exit the on_message
function.您的t1
变量是本地变量,因此当您退出on_message
function 时它会丢失。 Also, you're conflating the class task
and the instance t1
( task.stop()
won't work).此外,您将 class task
和实例t1
( task.stop()
不起作用)混为一谈。
For a quick fix, declare t1 = None
as a global, then add global t1
to your on_message
function...为了快速修复,将t1 = None
声明为全局,然后将global t1
添加到您的on_message
function...
However, I'd consider refactoring things so there's an always-running thread to command the Blinkt,.但是,我会考虑重构一些东西,以便有一个始终运行的线程来命令 Blinkt。 and the MQTT message handler simply sets its state accordingly – something like this, Dry-coded, obviously.并且 MQTT 消息处理程序只需相应地设置其 state - 显然是这样的,干编码。 so there may be some silliness.所以可能会有一些愚蠢。
from sys import exit
import blinkt
import threading
import time
MQTT_SERVER = "192.168.x.x"
MQTT_PORT = 1883
MQTT_TOPIC = "mytopic"
REDS = [0, 0, 0, 0, 0, 16, 64, 255, 64, 16, 0, 0, 0, 0, 0, 0]
start_time = time.time()
class BlinktManager(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.stop_event = threading.Event()
self.mode = None
def run(self):
while not self.stop_event.isSet():
self.tick()
self.stop_event.wait(0.1) # instead of sleep
def tick(self):
if self.mode == "reds":
self._tick_reds()
def _tick_reds(self):
delta = (time.time() - start_time) * 16
offset = int(
abs((delta % len(REDS)) - blinkt.NUM_PIXELS)
)
for i in range(blinkt.NUM_PIXELS):
blinkt.set_pixel(i, REDS[offset + i], 0, 0)
blinkt.show()
def clear(self):
self.mode = None
blinkt.clear()
blinkt.show()
def set_all_pixels(self, r, g, b):
self.mode = None
for x in range(blinkt.NUM_PIXELS):
blinkt.set_pixel(x, r, g, b)
blinkt.show()
def set_pixel(self, x, r, g, b):
self.mode = None
blinkt.set_pixel(x, r, g, b)
blinkt.show()
def begin_reds(self):
self.mode = "reds"
def on_connect(client, userdata, flags, rc):
print("Connected with result code " + str(rc))
client.subscribe(MQTT_TOPIC)
def on_message(client, userdata, msg):
data = msg.payload
if type(data) is bytes:
data = data.decode("utf-8")
data = data.split(",")
command = data.pop(0)
if command == "clr" and len(data) == 0:
blinkt_manager.clear()
if command == "rgb" and len(data) == 4:
x = data[0]
r, g, b = [int(x) & 0xFF for x in data[1:]]
if x == "*":
blinkt_manager.set_all_pixels(r, g, b)
else:
# TODO: error handling
blinkt_manager.set_pixel(int(x), r, g, b)
if command == "mtg" and len(data) == 0:
blinkt_manager.begin_reds()
blinkt.set_clear_on_exit()
blinkt_manager = BlinktManager()
blinkt_manager.start()
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect(MQTT_SERVER, MQTT_PORT, 60)
client.loop_forever()
Python program raising exceptions in a python thread Python 程序在 python 线程中引发异常
import threading
import ctypes
import time
class thread_with_exception(threading.Thread):
def __init__(self, name):
threading.Thread.__init__(self)
self.name = name
def run(self):
# target function of the thread class
try:
while True:
print('running ' + self.name)
finally:
print('ended')
def get_id(self):
# returns id of the respective thread
if hasattr(self, '_thread_id'):
return self._thread_id
for id, thread in threading._active.items():
if thread is self:
return id
def raise_exception(self):
thread_id = self.get_id()
res = ctypes.pythonapi.PyThreadState_SetAsyncExc(thread_id,
ctypes.py_object(SystemExit))
if res > 1:
ctypes.pythonapi.PyThreadState_SetAsyncExc(thread_id, 0)
print('Exception raise failure')
t1 = thread_with_exception('Thread 1')
t1.start()
time.sleep(2)
t1.raise_exception()
t1.join()
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