我正在构建一个看门狗计时器来运行另一个Python程序，如果它无法从任何线程中找到检查，则会关闭整个程序。这样做是为了最终能够控制所需的通信端口。计时器的代码如下：
from multiprocessing import Process, Queue
from time import sleep
from copy import deepcopy
PATH_TO_FILE = r'.\test_program.py'
WATCHDOG_TIMEOUT = 2
class Watchdog:
def __init__(self, filepath, timeout):
self.filepath = filepath
self.timeout = timeout
self.threadIdQ = Queue()
self.knownThreads = {}
def start(self):
threadIdQ = self.threadIdQ
process = Process(target = self._executeFile)
process.start()
try:
while True:
unaccountedThreads = deepcopy(self.knownThreads)
# Empty queue since last wake. Add new thread IDs to knownThreads, and account for all known thread IDs
# in queue
while not threadIdQ.empty():
threadId = threadIdQ.get()
if threadId in self.knownThreads:
unaccountedThreads.pop(threadId, None)
else:
print('New threadId < {} > discovered'.format(threadId))
self.knownThreads[threadId] = False
# If there is a known thread that is unaccounted for, then it has either hung or crashed.
# Shut everything down.
if len(unaccountedThreads) > 0:
print('The following threads are unaccounted for:\n')
for threadId in unaccountedThreads:
print(threadId)
print('\nShutting down!!!')
break
else:
print('No unaccounted threads...')
sleep(self.timeout)
# Account for any exceptions thrown in the watchdog timer itself
except:
process.terminate()
raise
process.terminate()
def _executeFile(self):
with open(self.filepath, 'r') as f:
exec(f.read(), {'wdQueue' : self.threadIdQ})
if __name__ == '__main__':
wd = Watchdog(PATH_TO_FILE, WATCHDOG_TIMEOUT)
wd.start()
我还有一个小程序来测试看门狗功能。
from time import sleep
from threading import Thread
from queue import SimpleQueue
Q_TO_Q_DELAY = 0.013
class QToQ:
def __init__(self, processQueue, threadQueue):
self.processQueue = processQueue
self.threadQueue = threadQueue
Thread(name='queueToQueue', target=self._run).start()
def _run(self):
pQ = self.processQueue
tQ = self.threadQueue
while True:
while not tQ.empty():
sleep(Q_TO_Q_DELAY)
pQ.put(tQ.get())
def fastThread(q):
while True:
print('Fast thread, checking in!')
q.put('fastID')
sleep(0.5)
def slowThread(q):
while True:
print('Slow thread, checking in...')
q.put('slowID')
sleep(1.5)
def hangThread(q):
print('Hanging thread, checked in')
q.put('hangID')
while True:
pass
print('Hello! I am a program that spawns threads!\n\n')
threadQ = SimpleQueue()
Thread(name='fastThread', target=fastThread, args=(threadQ,)).start()
Thread(name='slowThread', target=slowThread, args=(threadQ,)).start()
Thread(name='hangThread', target=hangThread, args=(threadQ,)).start()
QToQ(wdQueue, threadQ)
如您所见，我需要将线程放入队列.Queue中，而另一个独立的对象会慢慢将队列.Queue的输出馈送到多进程队列中。如果我直接将线程放入多进程队列中，或者在puts之间没有让QToQ对象休眠，那么多进程队列将会锁定，并且在看门狗方面始终为空。
现在，由于多进程队列应该是线程和进程安全的，我只能假设我在实现中出了问题。我的解决方案似乎有效，但也感觉很麻烦，我觉得我应该修复它。
我使用的是Python 3.7.2，如果有影响，请注意。
from queue import Queue)，但我无法使其失败。我可以直接通过wdQueue发送ID，也可以通过QToQ和队列发送ID，而Watchdog总是能够捕获到hangID并关闭程序。 - quamranaexcept应该改成finally。 - Davis Herring