How can I wait for all the threads I spawn for 5 minutes

[Steve Holden]

herman wrote:
> Hi,
> 
> In my python program, I would to like to spwan 5 threads, for the them
> for 5 minutes maximum and the continue. Here is my script:
> 
>             threads = []
> 
>             for j in range(5):
>                 t = MyThread()
>                 threads.append(t)
> 
>             for t in threads:
>                 t.join(60*5)
>                 print "thread join\n"
> 
>             # wait for 5 minutes for all the threads to complete ,
> and
>             # then continue
> 
> But this code ends up waiting 5 minutes for **each** thread.  that is
> not what I want. I just want to wait for 5 minutes for all threads.
> how can I do that?
> 
> And after 5 minutes, i want to kill off all the threads I spawn
> earlier, how can I do that in python.
> 
> Thank you for any help.
> 
Well, to answer your second question, there is no reliable way to kill a 
  thread without having the thread periodically examine some aspect of 
its environment that the main thread can change to indicate the 
requirement that the sub-thread terminate.

The easiest way to check the number of outstanding threads is to use 
threading.activeCount(), which tells you how many outstanding threads 
remain.

Here's some code I used in a test program recently:

     # As long as we have more than just the 'main' thread running,
     # print out a status message
     while threading.activeCount() > 1 :
         print "-- after", iterCount, "sleeps", \
               str(threading.activeCount()), "threads running in total"
         iterCount += 1
         time.sleep(1)
     print "Only main thread remains"

Clearly you will need to set some termination flag (a global variable 
would do) after time is up, and as long as your threads examine this 
flag you'll be good to go.

regards
  Steve
-- 
Steve Holden        +1 571 484 6266   +1 800 494 3119
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