[Tutor] How to stop a specific thread in Python 2.7?

[avi.e.gross at gmail.com]

There is a low tech approach if you are willing to let the thread run a
little longer or use up some time checking. I see others suggesting similar
things. 

There are many ways other parts of your program can set a flag that the
thread can occasionally check and then quit.

Some are as simple as creating a temporary file with a known name and the
thread would check periodically and when found, delete it and quit.

And, of course, various methods can be used for a sort of messaging in
memory.

But as noted by Mats, the best kill is suicide after settling your affairs.

In the real world, I suspect this is a solved problem. Imagine for example
if you decide to simultaneously attack a problem in multiple ways and the
first one to finish means the others need not continue. An example might be
trying to determine what language a paragraph is in that will start threads
checking to see if it matches one or another language and returning if the
likelihood is very high.

-----Original Message-----
From: Tutor <tutor-bounces+avi.e.gross=gmail.com at python.org> On Behalf Of
Mats Wichmann
Sent: Wednesday, September 25, 2024 4:27 PM
To: marc nicole <mk1853387 at gmail.com>
Cc: tutor at python.org
Subject: Re: [Tutor] How to stop a specific thread in Python 2.7?

On 9/25/24 13:57, marc nicole wrote:
> Why i want to kill a thread?
> 
> At first, i want to look for two values through a thread, if i got them 
> before an event happens, that's cool, the thread will end itself and i 
> will use the values in the subsequent code, if not i want to kill the 
> background running function/thread, and relaunch the function of thread 
> (blocking call this time) to get the values and then continue the program.
> 
> The context is robotics:

So to start out, from the documentation:

"currently, there are no priorities, no thread groups, and threads 
cannot be destroyed, stopped, suspended, resumed, or interrupted."

(see the bits just above this heading: 
https://docs.python.org/3.12/library/threading.html#thread-local-data)

So you need to find a way to extend your model to the negative case as 
well, so the thread stops itself even if the ideal case didn't occur.  I 
think one approach is to use Event, as you've already started to think 
about, I'd just change the naming to be more clear:


should_stop = threading.Event()
# then at some point:
should_stop.set()


and in your thread:

while not should_stop.wait(1):
     # do whatever work you can do


I'm guessing you've already been here and this isn't new info.  Maybe 
someone else has more experience...

 From stuff I've heard, robotics folks are making use of async I/O to 
solve these situations, rather than threads.  Unfortunately, Python's 
async is a bit of a pain as it's kind of like a virus: a function that 
calls async routines must itself be async, and so on... it kind of 
spreads throughout your program this way, and can be a lot of work 
unless you built it from scratch as async.



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