[newbie] accept()-ing process under supervision (was:Erlangish way of Iterator pattern)

[Joe Armstrong (AL/EAB)]

David Hopwood wrote

> 
> I would have thought you could separate the problems of 
> testing whether the
> processor is working (must be done from a different 
> processor), and testing
> whether each program on it is working (can be done from the 
> same processor,
> provided it is from a different language runtime).
> 
> Processors and programs don't tend to fail in ways that could 
> defeat this
> approach.

The first problem is difficult.

Suppose you have three machines A B and C

A thinks C is dead
B thinks C is alive
A can talk to B

... Byzantine generals and all that stuff ...

I have experience several situations where  the
machines appear to work, and the programs on the individual
machines appear to work - all test case etc. have been passed
and yet the systems manifestly do not work.

This occurs because we can't formally prove our systems
to be correct and our test cases only cover a small fraction
of the problem space - so we easily get deluded that are programs
are correct.

The only thing that I have confidence in is end-to-end
testing.

/Joe



> 
> -- 
> David Hopwood <david.nospam.hopwood@REDACTED>
>