thread stop python

1# Python program using
2# traces to kill threads
3  
4import sys
5import trace
6import threading
7import time
8class thread_with_trace(threading.Thread):
9  def __init__(self, *args, **keywords):
10    threading.Thread.__init__(self, *args, **keywords)
11    self.killed = False
12  
13  def start(self):
14    self.__run_backup = self.run
15    self.run = self.__run      
16    threading.Thread.start(self)
17  
18  def __run(self):
19    sys.settrace(self.globaltrace)
20    self.__run_backup()
21    self.run = self.__run_backup
22  
23  def globaltrace(self, frame, event, arg):
24    if event == 'call':
25      return self.localtrace
26    else:
27      return None
28  
29  def localtrace(self, frame, event, arg):
30    if self.killed:
31      if event == 'line':
32        raise SystemExit()
33    return self.localtrace
34  
35  def kill(self):
36    self.killed = True
37  
38def func():
39  while True:
40    print('thread running')
41  
42t1 = thread_with_trace(target = func)
43t1.start()
44time.sleep(2)
45t1.kill()
46t1.join()
47if not t1.isAlive():
48  print('thread killed')
49  
50In this code, start() is slightly modified to set the system trace function using settrace(). 
51The local trace function is defined such that,
52whenever the kill flag (killed) of the respective thread is set, 
53a SystemExit exception is raised upon the excution of the next line of code,
54which end the execution of the target function func.
55Now the thread can be killed with join().