[Stackless] You cannot __reduce__ the tasklet ...

[Arman Bostani]

Christian Tismer wrote:

> Arman Bostani wrote:
> 
>> Another dumb question: why do you want to forbid execution of pickled 
>> "current" tasklets?  What's special about them?
> 
> 
> It is that I cannot capture the current frame in a consistent
> way, since it is in a call to the tasklet's __reduce__ which
> is not stackless. So the current tasklet would always show
> up as one that raises an exception when run.
> But maybe this would be ok.
> This is where I wasn't sure about, but I agree that forbidding
> it is a half-assed solution. The idea of tasklet pickling
> is to pickle everything, even if it cannot be revived, just
> to have some state to inspect or partially execute.
> 
> I will change this when i get an idea what to do.

In our version of thread pickling, we have a capture() call which
pickles all frames up to the "capture" frame.  e.g.

def f():
    res = capture()
    if res:
	print 'captured', res
	# save res somewhere
    else:
	print 'unleashed'

capture() returns the pickled thread so it can be saved somewhere.
When res is unpickled (unleashed), the new thread behaves as if
capture() just returned with result 0.

I wonder if something like this is feasible with tasklets and the
__reduce__ call?

-arman

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