我有一个实现这样的线程的python程序：
class Mythread(threading.Thread):
def __init__(self, name, q):
threading.Thread.__init__(self)
self.name = name
self.q = q
def run(self):
print "Starting %s..." % (self.name)
while True:
## Get data from queue
data = self.q.get()
## do_some_processing with data ###
process_data(data)
## Mark Queue item as done
self.q.task_done()
print "Exiting %s..." % (self.name)
def call_threaded_program():
##Setup the threads. Define threads,queue,locks
threads = []
q = Queue.Queue()
thread_count = n #some number
data_list = [] #some data list containing data
##Create Threads
for thread_id in range(1, thread_count+1):
thread_name = "Thread-" + str(thread_id)
thread = Mythread(thread_name,q)
thread.daemon = True
thread.start()
##Fill data in Queue
for data_item in data_list:
q.put(data_item)
try:
##Wait for queue to be exhausted and then exit main program
q.join()
except (KeyboardInterrupt, SystemExit) as e:
print "Interrupt Issued. Exiting Program with error state: %s"%(str(e))
exit(1)
call_threaded_program() 是从不同的程序调用的。
我的代码在正常情况下工作。但是，如果其中一个线程发生错误/异常，则程序会卡住（因为队列连接是无限阻塞的）。我能够退出该程序的唯一方法是关闭终端本身。
当线程退出时终止该程序的最佳方法是什么？有没有一种干净的（实际上我会采取任何方式）这样做的方式？我知道这个问题已经被问过很多次了，但我仍然无法找到一个令人信服的答案。我真的很感激任何帮助。
编辑： 我尝试删除队列上的连接并使用全局退出标志，如Is there any way to kill a Thread in Python? 但是，现在的行为是如此奇怪，我无法理解发生了什么。
import threading
import Queue
import time
exit_flag = False
class Mythread (threading.Thread):
def __init__(self,name,q):
threading.Thread.__init__(self)
self.name = name
self.q = q
def run(self):
try:
# Start Thread
print "Starting %s...."%(self.name)
# Do Some Processing
while not exit_flag:
data = self.q.get()
print "%s processing %s"%(self.name,str(data))
self.q.task_done()
# Exit thread
print "Exiting %s..."%(self.name)
except Exception as e:
print "Exiting %s due to Error: %s"%(self.name,str(e))
def main():
global exit_flag
##Setup the threads. Define threads,queue,locks
threads = []
q = Queue.Queue()
thread_count = 20
data_list = range(1,50)
##Create Threads
for thread_id in range(1,thread_count+1):
thread_name = "Thread-" + str(thread_id)
thread = Mythread(thread_name,q)
thread.daemon = True
threads.append(thread)
thread.start()
##Fill data in Queue
for data_item in data_list:
q.put(data_item)
try:
##Wait for queue to be exhausted and then exit main program
while not q.empty():
pass
# Stop the threads
exit_flag = True
# Wait for threads to finish
print "Waiting for threads to finish..."
while threading.activeCount() > 1:
print "Active Threads:",threading.activeCount()
time.sleep(1)
pass
print "Finished Successfully"
except (KeyboardInterrupt, SystemExit) as e:
print "Interrupt Issued. Exiting Program with error state: %s"%(str(e))
if __name__ == '__main__':
main()
程序的输出如下：
#Threads get started correctly
#The output also is getting processed but then towards the end, All i see are
Active Threads: 16
Active Threads: 16
Active Threads: 16...
然后程序只是挂起或继续打印活动线程。然而，由于退出标志设置为 True，线程的 run 方法没有被执行。所以我不知道这些线程是如何保持的或发生了什么。
编辑：我发现了问题。在上面的代码中，线程的 get 方法被阻塞，因此无法退出。使用带有超时的 get 方法代替了诀窍。我有我在下面修改的 run 方法的代码
def run(self):
try:
#Start Thread
printing "Starting %s..."%(self.name)
#Do Some processing
while not exit_flag:
try:
data = self.q.get(True,self.timeout)
print "%s processing %s"%(self.name,str(data))
self.q.task_done()
except:
print "Queue Empty or Timeout Occurred. Try Again for %s"%(self.name)
# Exit thread
print "Exiting %s..."%(self.name)
except Exception as e:
print "Exiting %s due to Error: %s"%(self.name,str(e))