On Thursday, October 25, 2018 at 7:13:26 AM UTC-7, John Cremona wrote:
>
> sage: for res in apply([f,g]): print res; break
> (((<function f at 0x7fb0537d6050>,), {}), 3^2 * 12248508919 *
> 263416276811813669131602539468011)
>
> The first bit of the output shows that it is f which returns the result.
> But I don't know if g stops working because of the 'break' -- does it?
>
> I'm almost certain it doesn't. The iterator that is returned by
apply([f,g]) is not referenced by your code any more after the break, so it
might be possible it gets destructed at this point. Destruction at that
point could indeed send a kill to the child processes that haven't
completed yet (or terminate them otherwise), but in general you can't trust
that actions triggered by destruction will happen at particular times. As
far as python is concerned, a no-op gargabe collector would be a compliant
implementation.
Clearly what you should have is something along the lines of
A=apply([f,g])
res=next(A)
A.stop_remaining_processes()
del A #if you want
(this could be wrapped in a context manager so that you could do something
like)
with apply([f,g]) as A:
res=next(A)
I would expect the functionality is already there in the underlying library
that is used by @parallel, but it doesn't seem to be exposed on the wrapper
you currently get.
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