thread and alarm

[Sergey]

How to send alarm to a thread?
I can set alarm in main thread, but how then send exception to another thread to wake it if it executes too long?

[Antoon Pardon]

Re: thread and alarm

Op 2005-12-16, Sergey schreef <s323@mail.ru >:[color=blue]
> How to send alarm to a thread?
> I can set alarm in main thread, but how then send exception to another thread to wake it if it executes too long?[/color]

The short answer is you can't and you should preferably look for an
other solution. If for example your other thread is simple loop
like:

while condition:
...

You could change this to:

while not timeout and condition:

timeout is then a variable that could be set by a differnt thread.


If your code doesn't lend itself for this kind of solution you could
consider the following module I once wrote. However some caveats:

1) You need ctypes.

2) It can only interrupt a thread while it is excuting python
code. No interruptions while in C-extention code.

3) It is not extensivly tested. It was just a proof of concept
thing.

----

import os
import ctypes
from time import sleep
from random import randint

class TimeOut(Excepti on):
pass

class Alarm(Exception ):
pass

import threading

class Xthread(threadi ng.Thread):


def start(self):
self.__original _run = self.run
self.run = self.__run
threading.Threa d.start(self)

def __run(self):
self._thrd_id = threading._get_ ident()
try:
self.__original _run()
finally:
self.run = self.__original _run

def raize(self, excpt):

Nr = ctypes.pythonap i.PyThreadState _SetAsyncExc(se lf._thrd_id, ctypes.py_objec t(excpt))
#print self.id , "Exception Thrown" , Nr
while Nr > 1:
#print self.id , "Exception Canceled" , Nr
ctypes.pythonap i.PyThreadState _SetAsyncExc(se lf._thrd_id, None)
sleep(0.1)
Nr = ctypes.pythonap i.PyThreadState _SetAsyncExc(se lf._thrd_id, ctypes.py_objec t(excpt))
#if Nr == 0:
# print self.id , "Exception Canceled" , Nr
# ctypes.pythonap i.PyThreadState _SetAsyncExc(se lf._thrd_id, None)

def alarm(self, tm):

alrm = threading.Timer (tm, self.raize, (TimeOut,))
alrm.start()
return alrm

if __name__ == "__main__":

class Continue(Xthrea d):

def run(self):

self.id = os.getpid()
print self.id, self._thrd_id, "Begin"
i = 0
try:
for _ in xrange(randint( 0,20)):
for e in xrange(4 * 100000):
i = i + e
print self.id, "Finished"
except Alarm:
print self.id, "Interupted "

lst = [Continue() for _ in xrange(10)]

for T in lst:
T.start()

try:
sleep(10)
finally:
for T in lst:
T.raize(Alarm)