threading

[Edwin.Madari at VerizonWireless.com]

1. check out the Caveats for thread module: http://docs.python.org/lib/module-thread.html

Threads interact strangely with interrupts: the KeyboardInterrupt exception will be received by an arbitrary thread. (When the signal module is available, interrupts always go to the main thread.) 

i.e., all threads (including main) to catch interrupt exceptions, and propagate that information to  other threads.

2. since there is no way to interrupt a sleep (not aware of any), sleep is not the choice. use something  else like napping.  I mean, take shorter intervals of sleep, check every thing is fine and go back to napping. if something is fishy - go catch it.

hope that helps.
Edwin


-----Original Message-----
From: python-list-bounces+edwin.madari=verizonwireless.com at python.org
[mailto:python-list-bounces+edwin.madari=verizonwireless.com at python.org]
On Behalf Of Rhamphoryncus
Sent: Thursday, August 14, 2008 2:52 PM
To: python-list at python.org
Subject: Re: threading


On Aug 14, 3:30 am, "Mathieu Prevot" <mathieu.pre... at ens.fr> wrote:
> 2008/8/13 Parimala <parimal... at accord-soft.com>:
>
>
>
> > Hello,
>
> >        I am using python2.5.1 version to run my test scripts. I want to use
> > 'threading' module in my tests. As a startup program, I had run the
> > following one.
>
> > importthreading
> > import sys
> > import time
>
> > def hello():
> >   i=0
> >   try:
> >     while i<10:
> >       print "hi"
> >       time.sleep(1)
> >       i+=1
> >   except KeyboardInterrupt:
> >     print 'KeyboardInterrupt'
> >     raise KeyboardInterrupt
>
> > try:
> >   thread=threading.Thread(target=hello,args=())
> >   thread.start()
> > except KeyboardInterrupt:
> >   print 'KeyboardInterrupt'
> >   raise KeyboardInterrupt
>
> > once program starts, problem is..
> > I am not able to abort the thread using (CTRL+C) KeyboardInterrupt.  While
> > running if I press CTRL+C, it won't generate any exception until the end of
> > the execution. Once the execution gets over,  it will give "Exception
> > exceptions.KeyboardInterrupt in <module 'threading' from
> > 'C:\python25\lib\threading.py'> ignored" this message and exits.
>
> > I had gone through some documents, it says if a thread is joined with
> > .join() method then we can't stop that process until it releases the lock
> > what it acquired. But in the above program I didn't use .join() method but
> > still I am not able to abort the thread.
>
> > Could you please suggest me how can I abort the thread at any point in time
> > using CTRL+C.
>
> Hi,
>
> a terminate method is given here:http://sebulba.wikispaces.com/recipe+thread2
>
> so you can terminate the thread by:
>
> (...)
> t.start()
> (...)
>
> while True:
>   try:
>     #some code
>   except KeyboardInterrupt:
>     t.terminate()
>     break
>
> Mathieu

(For some reason the OP hasn't come through to groups.google.com..
odd)

Note that it won't interrupt any blocked I/O, which is often what you
need the most.  If your threads are CPU-bound you can simply have them
check a flag and exit if it becomes True.
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