multithreading-problem

[Manish Jethani]

Diez B. Roggisch wrote:

> Hi,
> 
> I expirienced strange problems when using the module threading:
> 
> class Bar:
>   def __init__(_, arg):
>     _.arg = arg
>   def work(_):
>     while 1:
>       print _.arg
> 
> def foo(arg):
>   b = Bar(arg)
>   b.work()
> 
> for i in xrange(4):
>   thread = threading.Thread(target=lambda : foo(i))
>   thread.start()
> 
> What I'd expect would be a sequence of prints like this
> 1
> 2
> 3
> 4
> 1
> 3
> 4
> 2
> 
> What I actualy get is this:
> 1
> 4
> 4
> 4
> 4
> 1
> 4
> 4
> 4
> 
> Placing a time.sleep(3) after the thread.start() fixed things. So it appears
> that the curried lambda passed as target is somehow a reference equal for
> all four invocations.

No, I don't believe it to be true.  It's probably just that the
other threads aren't getting a chance to run.  Consider
time.sleep(0) in the while loop in work()

-Manish

-- 
Manish Jethani (manish.j at gmx.net)
phone (work) +91-80-51073488