[英]How to terminate a thread in Python?
我知道這個話題已經討論過幾次,但是我已經嘗試過,或者至少嘗試了幾乎所有的解決方案,但是作為一個相當新的 python basher,我無法讓以前的任何解決方案起作用。
該腳本的基本前提是它訂閱了一個 MQTT 代理並等待命令,單個動作命令 100% 工作,但是其中一個命令需要一個循環無限期地運行,直到收到另一個命令,因此最合適的解決方案是在一個單獨的線程中運行“循環”,而主訂閱者循環繼續“監聽”下一個命令。
一切都在工作 95%,“靜態”命令通過並且任務運行良好,然后當“mtg”命令通過它時,線程和循環運行 100%,但是這是它失敗的地方,當收到下一個命令我可以確認“if”語句在將消息打印到控制台時處理命令,但是 thread.stop() 沒有運行,或者它可能運行但它不會終止線程 ---我正在拔頭發試圖弄清楚。
一些代碼:
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()
您的t1
變量是本地變量,因此當您退出on_message
function 時它會丟失。 此外,您將 class task
和實例t1
( task.stop()
不起作用)混為一談。
為了快速修復,將t1 = None
聲明為全局,然后將global t1
添加到您的on_message
function...
但是,我會考慮重構一些東西,以便有一個始終運行的線程來命令 Blinkt。 並且 MQTT 消息處理程序只需相應地設置其 state - 顯然是這樣的,干編碼。 所以可能會有一些愚蠢。
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 程序在 python 線程中引發異常
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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