[lsst-dm-stack-users] A few Lessons Learned

[Kian-Tat Lim]

Dave,

> 1) There really needs to be a "DM For Dummies" document.

	Agreed, although it's not clear that we're at the stage that we
want to or can support true "Dummies".

>    a) Code:  The sequence for updating a package, and the subsequent
>         failure of another package due to new needs in the updated
>         package, is pretty frustrating.

	We need to better define releases of the code that work together
and update them faster.  The latest v6_1 release should help a bit, as
should the reappearance of lsstactive, so that there's a one-step way to
get all needed packages.

	eups distrib install -t v6_1 lsstactive

> 2) When Paul managed to drag me to the finish line, I was greeted by
>    astoundingly poor performance.  Not only did I not really know what
>    I could or should do, but the simple test case took 2 hours to find
>    stars in a single image.  Paul managed to trace this to the default
>    for "scons" is for no optimization.  When rerun with "scons opt=3",
>    the performance went from 2 hours to 2 minutes.  It would have been
>    really nice for the defaults to be reasonable, or at least for the
>    cookbook to tell me what to type to get useful results.

	If you're not building from git clones but instead just
installing already-released packages, which is now possible, this should
not be a problem.

> 3) My "success" is that I can run the DECam package on my own machine
>    using the single instruction that Paul told me about.  I have literally
>    no idea what other things I can (or should be able to) do with the
>    DM Stack.  My suggestion to Mario is (still) to have some sort of
>    AAS discussion of "why" one should spend the time and energy to use
>    the DM Stack.

	An overview of the available pipe_tasks would be good to have,
even before we get into how easy/hard it is to build your own.

-- 
Kian-Tat Lim, LSST Data Management, ktl at slac.stanford.edu