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Re: Executing a file only on later passes


From: Wipf, Stefan
Subject: Re: Executing a file only on later passes
Date: Mon, 03 Nov 2003 13:01:13 -0600

We've disabled the second pass. I can't think of all the reasons
just now, but the ones that immediately come to mind are:


- Relying on the second pass to resolve hidden dependencies is
  not reliable and just seems wrong.
- it obscures dependencies and can make an already complex
  configuration very convoluted.
- Often order does matter.  Sometimes things do not get done
  unless the order is right
- Most importantly, there does not seem to be a real need for it.
  There is nothing stopping us from explicitly forcing as many
  passes as needed on a per action basis in in the action sequence.
  This gives more refined control than to brute force a global
  second pass.



address@hidden wrote:
> 
> Chip, John,
> 
> The second pass is just like the next invocation of cfagent.
> Nothing will change by eliminating it except that the system will
> not be completely configured in a single iteration. The ordering
> of events is nothing to do with this. It just speeds up convergence
> for 90% of cases with hidden dependencies.
> 
> > OK.  It does cause things to sometimes (rarely) be executed in an
> > unexpected order, however.  Life might be made easier if we made this a
> > bit more user-accessible; for example, define a 'laterpass' class (or
> > something similar) after the first pass is done.  This would aid in
> > debugging (add a !laterpass condition and see if the problem persists
> > and the like) and allow for some clever hacks.
> 
> The second pass is only used if there are classes defined that have
> restricted the first pass, leaving some potentially unexecuted actions
> that would not be possible to evaluate.
> 
> If you want to control the order of things (which should not be
> necessary if you just trust the agent) then reorganize the
> input files. But who cares what the order is if it gets done?
> 
> > This isn't a major problem, but it can be frustrating.  No doubt this
> > frustration is exacerbated by a lack of grokking on my own part.
> >
> 
> Yup. Whern things get complex they are hard to understand.
> M
> 
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