Hi Nils!
On 2012-09-06, Nils Bruin <nbr...@sfu.ca> wrote:
>> And perhaps a decisive question: Do the parallel computations have
>> anything to do with weak references? Are instances of
>> UniqueRepresentation involved? Or UniqueFactory? These are changed by my
>> patches.
>
> Not that I could find. However, the first thing the subprocess does is
> invalidate all expect interfaces:
>
> sage/parallel/use_fork.py:213
>
> try
> ...
> sys.stdout = open(out, 'w')
> ...
> if self.reset_interfaces:
> sage.interfaces.quit.invalidate_all()
> ...
> except Exception, msg:
> # Important to print this, so it is seen by the caller.
> print msg
> finally:
> sys.stdout.flush()
> os._exit(0)
>
> We've seen before that invalidated expect interfaces can interact
> unexpectedly with weakreffed stuff in entirely unrelated places.
Is it known how the interaction occurs? Is there a ticket or an example
explaining the relation?
> If you want to get to the bottom of this one, I think you might want
> to instrument "use_fork.py" a little to see what's happening.
I also tried trace("..."), and it seems that the problem was still
visible. I say "it seems", because at some point my impression was that
some I/O process was locked - either that, or my ssh connection was not
responsive...
Best regards,
Simon
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