Hi Chris,
Thanks a lot for such a comprehensive reply, I got it fixed now. Thanks
again :)
On Tue, May 5, 2015 at 2:52 PM, Chris Angelico <ros...@gmail.com> wrote:
> On Tue, May 5, 2015 at 7:23 PM, david jhon <djhon9...@gmail.com> wrote:
> > from threading import Timer, Lock
> >
> > class miTestClass(EventMixin):
> > def __init__(self, t, r, bw):
> > self.statMonitorLock = Lock() #to lock the multi access threads
> > self.statMonitorLock.acquire()
> > statMonitorTimer = Timer(10.0, self._collectFlowStats()) #timer
> to
> > collect stats
> > statMonitorTimer.start()
> >
> > but I am getting following error:
> >
> > Exception in thread Thread-4:
> > Traceback (most recent call last):
> > File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
> > self.run()
> > File "/usr/lib/python2.7/threading.py", line 1082, in run
> > self.function(*self.args, **self.kwargs)
> > TypeError: 'NoneType' object is not callable
>
> The Timer() class will call a function when it's ready. To use that,
> you want to pass it a function. Try putting these two lines of code
> into your __init__ function:
>
> print(self._collectFlowStats)
> print(self._collectFlowStats())
>
> (Aside: This is something I like to call "IIDPIO debugging": If In
> Doubt, Print It Out. You sometimes have more sophisticated debugging
> techniques available, but you hardly ever are unable to basic 'print',
> in some form or another. It's incredibly useful.)
>
> The first one will print out something like this:
>
> <bound method miTestClass._collectFlowStats of <__main__.miTestClass
> object at 0x12345678>>
>
> The second will actually call that function (which may or may not do
> anything visible), and then print out:
>
> None
>
> If you change your _collectFlowStats function a bit, you can see even
> more of what's happening. Something like this:
>
> def _collectFlowStats(self):
> print("_collectFlowStats has been called. Returning 42...")
> return 42
>
> Then you'll see that it gets called, and does its print, and then 42
> gets printed out at the end.
>
> In your case, simply removing the parentheses from
> self._collectFlowStats should do what you want - the Timer constructor
> will be passed a function (in this case, a bound method, but same
> same), and that function won't be called until the timer is up.
>
> Hope that helps!
>
> ChrisA
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