Re: System deployment commands hoarding all RAM

[Sergio Pastor Pérez]

Hi Juliana,

Thanks for your help on the matter!

After reading your explanation about tail recursion I understand the
concept much better.

I still need to find a way to implement the problematic code in a
tail-recursive fashion. But, I'm not convinced that it will solve the
problem. Specially since issuing the `apply-to-record-type` over an
operating system record yields a short computation time:
--8<---------------cut here---------------start------------->8---
scheme@(pastor utils gpu-specification)> 
,time (begin ; Avoid printing the output
        (apply-to-record-type
         (lambda (pkg)
           pkg)
         (@ (guix packages) <package>)
         (@ (base-system) %base-gnome-system))
        #f)
$15 = #f
;; 0.007433s real time, 0.007428s run time.  0.000000s spent in GC.
--8<---------------cut here---------------end--------------->8---

I'm not able to use the profiler to display how deep the recursion
grows. In any case, I believe it should grow equally for the following
invocations:
--8<---------------cut here---------------start------------->8---
λ guix system build transformed-sheepbook.scm
/gnu/store/kpk9la4h9xwp6n7vabd5lfs6kbhb2f2d-system

λ guix system vm transformed-sheepbook.scm
Killed
--8<---------------cut here---------------end--------------->8---

Since the second one hoards the RAM, I'm guessing that the commands
operate differently over the resulting operating system record.

I'm not able to dig further since the `guix repl` does not support
tracing, and using a pure Guile REPL errors out whenever I try to use
trace points for this procedure:
--8<---------------cut here---------------start------------->8---
scheme@(pastor utils gpu-specification)> ,tracepoint apply-to-record-type
scheme@(pastor utils gpu-specification)> ((@ (guix scripts system) guix-system) 
"vm" "/home/pastor/.config/guix/systems/transformed-sheepbook.scm")
ice-9/boot-9.scm:1685:16: In procedure raise-exception:
In procedure port-column: Wrong type argument in position 1: #<closed: string 
7fa2d32dd000>
--8<---------------cut here---------------end--------------->8---

Interestingly, the traces work when using the `build` command instead of
the `vm` command:
--8<---------------cut here---------------start------------->8---
scheme@(pastor utils gpu-specification)> ((@ (guix scripts system) guix-system) 
"build" "/home/pastor/.config/guix/systems/transformed-sheepbook.scm")
Trap 0: (apply-to-record-type #<procedure 7fa2aed6e868 at transformed-sheep…> …)
Trap 0: |  (apply-to-record-type #<procedure 7fa2aed6e868 at transformed-sh…> …)
...
/gnu/store/6xxzsp3grp53x9w49wh513i8sjyal3zg-system
--8<---------------cut here---------------end--------------->8---

I think I've hit a road block.

Does any fellow Guix hacker knows a way to debug `guix system` commands
or why the `vm` subcommand does not make the same computation over the
record as the `build` subcommand does?


Thanks again for your time.
Regards,
Sergio.

PS: I appreciate the book recommendations!